Powering the Fuji X-T3

A SURVEY OF OPTIONS AND STRATEGIES

This comprehensive reference guide assembles information relevant to supplying power to the Fujifilm X-T3 camera, in an optimal way. The level of examination ranges from broad system overviews, to detailed analysis suitable for persons who are using the X-T3 professionally. Although this information is presented within the context of the X-T3 camera, much of it (particularly the information regarding NP-W126 type batteries) is also relevant to other Fuji X-series cameras. I hope that this can help you to get the most out of your Fujifilm camera. There is an important disclaimer at the end of this guide. Please read it before acting upon any information given here.

CONTENTS

A - OVERVIEW

Body only power configuration options
Body and grip power configuration options

B - NP-W126S & NP-W126 BATTERIES

Specifications
Distinguishing between S and non-S
Performance differences
Determining the production date

C - NON-OEM BATTERIES

Genuine vs non-OEM batteries
Discharge characteristics
Identifying counterfeit batteries

D - VERTICAL GRIP

Battery discharge sequence
Battery deployment strategies
9 Volt DC input options
USB boost cable (5V step up to 9V)

E - LITHIUM-ION BATTERIES

State of health
State of charge
Calendar fade
Cycle fade
Detriments to service life
Charging
Charge rates
Charging times
Voltage limits for charge and discharge
Temperature limits
Voltage stabilisation
Measuring battery voltage
Battery contacts
Self-discharge
Storage
Determining the battery's end of life
Li-ion fire hazard

F - POWER MANAGEMENT SETTINGS

View Mode setting
Auto Power Off setting
Power management menu
Boost mode
Performance mode differences

G - EXTERNAL CHARGERS

BC-W126S / BC-W126
Non-OEM chargers
Unexpected Interactions
Over-temperature protection

H - X-T3 USB PORT

Connection mode
Connector types
USB "Power Delivery"
Internal charging
External powering
USB power sources
Fujifilm AC-5VF power adapter

I - POWER BANKS

Advantages
Branded power banks
Port capabilities
Expected output current
Removable battery power banks
Expected efficiency
Multi-voltage power banks
Bicycle light battery boxes
Power banks recommended by Fujifilm
Capacity limits for air transport

J - DC COUPLER

Attachment
9 Volt supply options
D-Tap
Applications & examples

K - Alternative Power Supplies

Automotive power
Buck converters
How to use solar power

L - USB Power Meters

M - Disclaimer

SECTION - A

OVERVIEW

Currently (early 2019), the X-T3 camera boasts the most sophisticated and versatile power management system of any X-series camera to date. Many of its power management improvements were introduced with the X-T2 model. The significant differences between the X-T3's power system, and the very similar power systems of the X-T2 and X-H1, are the X-T3's adoption of the USB-C standard for USB connection, and the ability to achieve maximum performance without having to use the optional battery grip.

The electrical specifications of the X-T3, are found on the identification and compliance plates. The one belonging to the camera body, is at the back of the tilt LCD screen, and can be seen when the screen's top is pulled outward, while the other plate is found on the top surface of the optional vertical grip. Both state that the camera is rated at 9 Volts up to a power of 18 Watts.

In terms of power options, use of the grip adds some, but at the same time, obstructs some others. For instance, while the grip is attached, there is no access to the camera body's battery chamber. Because of this, there are two slightly different power configuration schemes for the X-T3, depending on whether or not the optional vertical grip is used.

When the optional VG-XT3 grip is used, it is possible to leave the grip attached quasi-permanently, since there is no need to access the body battery for external charging, (although, you still have the external charging option, if desired).

Section - B

NP-W126S & NP-W126 BATTERIES

The NP-W126S is the specified battery for the X-T3 system (X-T3 body and optional VG-XT3 grip). Because some X-T3 owners might already have NP-W126 (non-S) batteries from an earlier camera, and they would like to use those batteries in the X-T3, the distinction between the two battery types can become an issue. The newer NP-W126S battery is a higher performance version of the NP-W126 battery, and was introduced to meet the needs of the X-T2 camera. These requirements on battery capability are extended further by the X-T3's even higher performance specification. To the question "Can NP-W126 (non-S) batteries be used in the X-T3?", the short answer is "Yes, but the camera may not be able to perform at its highest specification potential". For some types of photography (for instance, Landscape photography, and Product photography) a reduction in "speed" performance, may simply not be an issue.

The NP-W126 and NP-W126S batteries are identical in terms of physical dimensions and power capacity, and may be considered interchangeable for lower paced situations where top performance is not required.

The specific internal difference between the two battery types is the lower internal resistance characteristics of the "S" version. Low resistance enables high current flow with minimal temperature rise. The readily identifiable visual indicator of battery type is the orange square on the end of regular NP-W126 batteries, and the orange circle (plus the orange insertion direction arrow) on the NP-W126S batteries.

BATTERY TYPE DISCRIMINATION BY X-T3
When the X-T3 is powered up, any battery that is not an NP-W126S (this includes the NP-W126, and non-OEM batteries), is identified. The X-T3 determines the type by measuring for high resistance (about 680kΩ or higher) on the [S] contact of the battery, to indicate an "S" type battery. (If you tape over the [S] contact of a non-S type battery, effectively giving it infinite resistance, the X-T3 will mistakenly recognise that battery as an NP-W126S battery). If three batteries are loaded (1 in the body, 2 in the grip), at power up, the battery symbols for the grip batteries, display briefly with the "three dots" (meaning the battery's state of charge is being assessed). At this stage, the "S" or "non-S" battery type has already been determined, and Left and Right grip battery indicators show in either white (for "S" type) or yellow (for "non-S" type battery).

Within one second, the display shows all three battery indicators, with their appropriate charge levels, and displayed in either white or yellow. Any yellow display (meaning a "non-S" battery is detected), will be accompanied by a message recommending the use of NP-W126S batteries.

Note that the message uses the advisory "Please use …" rather than the imperative "You must use …". This, as well as the fact that the camera continues to work, indicates that the message is to be taken as an recommendation, rather than a directive.

PERFORMANCE DIFFERENCES
The performance differences between the regular and the type-S battery, are to do with sustained high power delivery over time, rather than with stored capacity. The type-S battery was intended to meet the increased endurance requirements of the previous X-T2 camera, when operating in scenarios such as high-rate continuous stills shooting, and long duration 4K video capture. Without the higher performance battery type, sustained high power usage could produce elevated battery temperature, an increase of the battery's internal resistance, and a drop in output voltage, leading to possible camera "lock-up" events. In a lock-up event, the camera becomes unresponsive to all controls, including the on/off switch. Typically, the batteries must be removed and re-inserted before operation can be restored. The NP-W126S battery's lower internal resistance characteristics were designed to address such issues. At the time of introduction (for the X-T2) Fujifilm stated that the improved battery could deliver three times longer duration of continuous shooting, even under 40 ℃ environmental conditions. However, for less demanding usage scenarios, the regular NP-W126 battery should perform satisfactorily, although with limitations to the X-T3's boost mode.

PRODUCTION DATE
The battery's performance potential declines over time, even if not being used. Therefore, in order to assess their service viability, it is useful to be able to determine the age of the NP-W126 class batteries, via their production date. This is recorded via an impressed alpha-numeric code on the end of the battery opposite to the electrical contacts end.

NP-W126 batteries having codes beginning with T, S, R, and P, had 5 characters. For codes beginning with N, and then on all NP-W126S batteries, the code is extended to 8 characters. (Please note that very early versions of the battery, prior to having the orange orientation patch, used a different production code system to the one described here). Of the 8 characters, the first three are the date code, the middle two (usually "1A" or "2A"), are undisclosed production information, and the last three are a manufacturing plant code. Note that Day of Month codes, don't use alphabetic upper-case "I", to avoid confusion with numeric character "1", one. (However, this is not an issue for Year and Month codes, which don't use numbers at all). For similar reasons, zero, "O" and "Q", are not used. To the camera user, it is the first two characters (indicating year and month) that are of interest.

The production date information can be decoded by using the chart below. In the above illustration, the "KGT" date code can be decoded as "2018, July, 26". Note that the year of production code proceeds in a reverse order. As a consequence, a letter closer to the beginning of the alphabet represent more recently produced battery. Since a Li-Ion battery's prime operating condition only lasts about two years it is worthwhile remembering the year codes representing the last two years, since these represent the batteries that are currently within their prime. Batteries beyond the two year period may still be usable for casual photography, but for critical and high power demand usage, batteries within the recent two year production period, should be preferred.

At time of release, the X-T3 should have been supplied with a battery whose production code starts with K. As we get a few months into 2019, production codes starting with J should start showing up.

SECTION -C

NON- OEM BATTERIES

Non-OEM (Original Equipment Manufacturer) batteries are also known as third-party batteries. Batteries that are "nominally" equivalent to the NP-W126, but not genuine Fujifilm batteries, (and therefore, not manufactured by Panasonic Energy Wuxi), are readily available, and at prices significantly below the price of the genuine NP-W126S batteries. Although the nominal specifications may suggest the non-OEM battery as a viable alternative to the genuine battery, there can be significant performance, behavioural, and safety differences.

GENUINE Vs NON-OEM BATTERIES
Although more costly in the short term, genuine Fujifilm batteries offer the following advantages over non-OEM batteries:

Stated capacity is reliable. The genuine Fujifilm batteries are rated at a capacity at or close to the maximum that is attainable for the technology, and their nominal capacity matches their actual capacity. Third-party batteries claiming significantly higher capacities are generally overstated.

The genuine Fujifilm batteries can fully utilise the camera and charger's power management system. This means that all four battery contacts, [+], [T], [S], and [-], are functional. On some non-OEM batteries, the [T] and [S] contacts are either set at a fixed value, or un-connected to any appropriate circuitry. This non-functionality of the [T] (temperature control) could have safety consequences.

The genuine Fujifilm battery's designation as a high performance "S" type, is reliable. Non-Fuji batteries can make this claim, as a pretense, by simply labelling them as an "S" type, and changing the resistance value on the [S] contact from 100kΩ to 680kΩ, without any other internal changes to the "non-S" chemistry or construction. (The camera will report this fake as an NP-W126S battery).

Production date, and so the age of the genuine battery, can be established with certainty. This can be very important for long term power management and planning. Also, if you are able to inspect a battery, before purchase, you could avoid purchasing old stock (bearing in mind that, for distribution and and logistics reasons, we could expect even the "freshest" batteries to be several months past their production date).

There could be warranty implications. If the camera was damaged as a result of a battery defect, obviously the question of whether the battery was a genuine Fujifilm battery, or a non-OEM battery, would be crucial to the outcome of any warranty claim.

Capacity against voltage profile is as expected by the system, so the battery level indicator works as it was designed to.

Extensive information regarding differences between The Fujifilm battery and non-OEM alternatives, is given in The Great Battery Brawl.

DISCHARGE CHARACTERISTICS
The relationship between, battery voltage, remaining capacity, and expected time before power is depleted, is non-linear. The discharge curve for the genuine NP-W126S battery differs from that of other batteries. Unlike the fairly simple curve of the genuine batteries, the discharge curve of the third party batteries tends to be more complex, with multiple inflections. Since the camera's battery monitoring system is calibrated against the discharge curve of the genuine NP-W126S battery, the camera will not read the current capacity of other batteries accurately (unless the battery happens to have exactly the same discharge profile as the genuine NP-W126S battery). Unfortunately, this renders the X-T3's ability to give detailed percent-remaining capacity information for non-Fuji batteries, not very meaningful.

TESTING THE DISCHARGE CHARACTERISTICS
Genuine NP-W126S batteries, and representative non-OEM batteries, were tested in order to establish the discharge characteristics against the battery level indicator. Each battery was fully charged using the supplied BC-W126S charger. When fully charged, the battery was removed and allowed to rest for 90 minutes, so that the open-circuit voltage could stabilise. The voltage was measured and recorded, and the battery was inserted into the X-T3. 4K video shooting was initiated. As soon as the indicator dropped by one bar (an "indicator event"), the video was terminated. The battery was removed immediately, and its open-circuit voltage measured and recorded. The duration of the video recording was used as a measure of elapsed time. The camera and battery were allowed to rest for a 10 minute cooling time, before the battery was again inserted, and video shooting re-initiated, until the next battery indicator event. This process cycle was repeated until the eventual camera shutdown, due to depleted battery.

After testing, I differentiated the results into 3 groups, which I have arbitrarily called type 1 (the genuine Fujifilm batteries), type 2, and type 3. The results for batteries within each type group, have been averaged, in order to give a very generalised view of the discharge behaviour typical of that battery type. Please note that, because the testing placed the batteries under very high stress, the results could be considered as those of a worst case scenario. You may actually get better discharge behaviour than what these results indicate.

TYPE 1 - GENUINE FUJIFILM NP-W126S BATTERIES
Because the battery level monitoring system of the X-T3 is calibrated against the genuine Fujifilm battery, the indicator symbols when using that battery, are informative, reliable, and accurate. Note that the remaining charge percentage and the remaining runtime percentage, don't exactly match, because their relationship is non-linear.

Perhaps most importantly, the indicator gives adequate warning before system shutdown due to battery depletion.

TYPE 2 - TYPICAL HIGH CAPACITY NON-OEM BATTERIES
These batteries are well regarded by some people, because they deliver similar capacity to the genuine Fujifilm batteries, but at only a fraction of the price. However, they have the least conformity to the X-T3's calibration curve. Their actual degree of discharge is always higher than what is shown by the battery indicator, and this discrepancy increases as the battery discharge progresses. By the time the indicator displays 2 bars, the battery is almost fully discharged, and low-battery shutdown follows quickly, with little or no warning.

Notice that this type of battery may not display the one bar battery symbol, but goes straight from two bars to empty.

TYPE 3 - TYPICAL LOWER CAPACITY NON-OEM BATTERIES
These batteries are low cost, and typically have capacities in the range of 1000 - 675mAh, (which may be overstated on their label, by up to 45%). At the beginning of discharge, the actual charge remaining is slightly higher than indicated, then at about midway (3 bars) the display is fairly accurate, and finally, in the low number of bars, the actual charge remaining, is less than indicated. Due to the fact that the battery has a lower maximum capacity to begin with, full depletion is reached very quickly, when the indicator is in the low number of bars. By the time the indicator displays 1 bar, the battery is almost fully discharged. If the low-battery warning is given, shutdown might follow within a couple of seconds.

Because of their lower capacity, these batteries tend to overheat when charging, (the charging current, which has been chosen for a 1260mAh battery, is too high for the lower capacity), and so these batteries often become swollen if the charger does not implement over-temperature protection.

IDENTIFYING COUNTERFEIT BATTERIES
Simply being a non-OEM battery, does not make a battery counterfeit. To be counterfeit, there must be an attempt to deceitfully pass (via fake packaging and labeling) the battery as a genuine Fujifilm battery. Suspicions regarding the battery's authenticity generally arise from, low purchase cost, poor performance, or the experience of the battery having a tight fit in the battery chamber. The following anomalies, (a more comprehensive list can be found in NP-W126S COUNTERFEITS: A Visual Guide to Spotting the Fakes), can help distinguish counterfeit batteries from the genuine (manufactured for Fujifilm by Panasonic) batteries:

Check the dimensions of the printed area of the suspect battery against those of a known genuine battery. When the printed information on the genuine battery was scanned for the purpose of reproduction on the counterfeit, some re-scaling may have taken place, leading to a slight difference in the bounding dimensions of the information printed on the battery.

Weigh the battery, with accurate electronic scales. Genuine batteries weigh very close to 47g / 1.7oz. Non-OEM batteries can be anywhere in a range of about 39-50g.

Check the flatness of the printed sides of the battery. Genuine Fujifilm batteries have a concavity to the sides, which can be seen by placing a straight-edge against them, and viewing against a bright background. The concavity can even be felt by rubbing over the surface with your finger. The genuine batteries will not have flat, or convex (bulging in the middle) sides.

Check the production code information on the end of the battery. Possible anomalies include: non-existent code, non-conforming code, or code that is ink-printed (rather than heat-impressed). In the following photograph, the battery with code starting KGT, is genuine, while the one with code starting MGW (printed in white ink), is a counterfeit.

A counterfeit battery may not show all of these anomalies, but it is likely to show several of them.

Section - D

VERTICAL GRIP

The Fujifilm VG-XT3 vertical grip (from this point on, simply referred to as the "grip") is an option designed to facilitate use of the camera in "tall" or "portrait" orientation, as well as providing further power options to those given by the body alone.

The grip can be used with either two or one batteries, or even without batteries, (if you want the "tall" format ergonomics, but don't need the weight of extra batteries). It can also be used, either attached to, or separated from the camera, as a dual battery charger. Charging takes approximately 120 minutes (when charging two batteries simultaneously) . Note that the Owner's Manual (p. 247), states: "Use only NP-W126S batteries".

BATTERY DISCHARGE SEQUENCE
For battery management reasons, you may sometimes want to prioritise a battery for discharge. As a general rule, the batteries are discharged starting from the left, and working towards the right. For light duty power demand, the three batteries are discharged in the following sequence: First, the left-hand grip battery, next, the right-hand grip battery, and finally, the body battery.

For sustained high power usage (continuous shooting, and high power demand video), the body battery supplements the power supplied by the currently designated-for-discharge grip battery, with the body battery being discharged at a lesser rate than the grip battery. The discharge sequence in this case is: First, the left-hand grip battery plus body battery, next, the right-hand grip battery plus body battery, and finally, the body battery.

BATTERY DEPLOYMENT STRATEGIES
You may be using a mix of batteries that differ in both type and age. The arrangement of the batteries in order of far grip battery to body battery, may have implications for your workflow. Also, certain battery arrangements could, if used for a long period of time, result in some batteries being under-utilised, and others being over-utilsed. For the sake of both efficiency and economy, it may be worthwhile putting in place an appropriate battery deployment strategy.

MIX OF "S" AND "NON-S" BATTERIES
If using a mix of non-S and type-S batteries, it is recommended to place an "S" battery in the camera body. When the batteries are assigned this way, the camera can always have access to the highest performance type battery, even if the other two batteries have become discharged.

EXPLOITATION STRATEGY
The exploitation strategy pushes your best (youngest) battery to the front of the discharge queue. This gives maximum usage value in terms of total lifetime shots against the purchase price of the battery. An advantage is that batteries are never under-utilised, and the strategy is very cost efficient. A disadvantage is that you can start with plenty of power at the beginning of a session, but the second and third batteries discharge more quickly than the first, so you may get less warning when all batteries having become depleted. It's a good strategy if your shoot sessions are typically short.

CONTINGENCY STRATEGY (CONSERVATION STRATEGY)
The contingency strategy pushes your best (youngest) battery to the rear of the discharge queue. It considers the grip batteries as the working batteries, and the body battery as a back-up or contingency battery. Applying this strategy, when both of the grip batteries have become discharged, you should plan to replace or recharge them immediately, rather than continuing to photograph and running down the body battery. This strategy helps to ensure that you always have reserve power, so that you don't lose power at some critical point in shooting, and also avoids having to regularly remove the grip to change a flat body battery, during the shoot. In this strategy, your "best" battery, is being kept in reserve, to ensure that you are able to cope with any unforeseen circumstances. The down side of this strategy is that the "contingency battery" may be under utilized during its typical two years of life expectation. Of course, whenever a new battery is purchased, it takes the place of the reserve battery, and the old reserve battery can be places in the grip as a working battery. This usage strategy is good for long shooting sessions, where you typically have to do battery replacements during the shoot.

ROTATION STRATEGY
This strategy distributes the usage over each of the batteries, so that none of them become overused or underused. This strategy is particularly recommended if you typically don't remove your batteries from the camera and grip (that is, you use internal charging methods). The position of each battery in the system is rotated on a regular interval basis. An ideal interval would be a monthly cycle.

In a (say) five battery system (one in the body, two in the grip, and two spares), the two additional batteries can also be inserted into the rotation sequence, but you may have to do some record keeping, so that you can determine the correct sequence at rotation time. Be aware that, if all of the batteries were of approximately the same age, at the beginning of this strategy, they will all start to show signs of aging (decreased exposure counts) at approximately the same time (about two years on). So this strategy works better if a new battery is purchased at regular intervals (say, at the end of the first year, and then every six months), which should not be an unreasonable demand if working professionally.

9V DC INPUT
A DC power input socket (EIAJ-03) is under the rubber seal on the left-hand side of the grip.

This socket is intended for the AC-9VS power adapter, that is supplied with the grip, and which can be used for both charging and supplying operational power, although not simultaneously. When the camera is turned off, the 9 Volt input will supply power for charging the grip batteries (but not the body battery). If the camera is turned on, then the 9 Volt input will supply power for camera operation.

The camera can operate without batteries if powered via the 9 Volt input, although to attain the camera's highest performance, it may be necessary for the DC input to be supplemented by some battery power, (at least one partially charged battery).

DC INPUT PLUGS
There is the possibility of supplying 9V power using power sources other than the AC-9VS. However, for operation without batteries, the voltage supplied via the DC socket, should not go below about 8.75 Volts; otherwise the display will flash the low power symbol (red battery with no bars), and the camera will auto power-off. The grip's DC input is a standard socket complying with the relevant Japanese standards, and accepts an EIAJ-03 plug.

This socket is not compatible with plugs adhering to the other common standard, which is IEC 60130-10, although one of that standard's plugs will loosely fit the socket in a way that is neither secure nor reliable. If using a 9 Volt power source other than the AC-9VS power adapter, it may be necessary to make up the appropriate cable (soldering and polarity discrimination skills required), in which case, the proper camera-end plug can be identified from the following table:

If searching online, the plug will typically be identified as a 4.8 x 1.7 mm plug. The "signature" yellow plastic tip, while common on the EIAJ-03 plug, is not unique to it, nor is it required by the standards. (In fact, Fujifilm uses a black plastic tip). However, the yellow tip can be a useful indicator of possible-candidates when searching for an appropriate plug.

USB BOOST CABLE
The USB boost cable (5V to 9V step up), is a further option for supplying power via the grip's DC input socket. It is recommended that you only use one battery in the grip when using the boost cable (the reason is given further down). The USB boost cable can be plugged into any suitable USB power source, such as a power bank, a personal computer, or a USB wall convertor. Typically, you would need a 5.5 x 2.1mm female to 4.8 x 1.7mm male adapter or conversion cable, in order to connect the converter to the VG-XT3's DC input socket.

The standard USB 5 Volts is up-converted to 9 Volts, with however, a corresponding reduction in the supplied current. For example, if the power bank can supply 5 Volts at a maximum of 2 Amps (5V x 2A = 10 Watts), then the boost cable won't be able to supply more than about 1.11 Amps of current (9V x 1.11A = 10 Watts) after the voltage conversion. The actual current will be less than this, if we take conversion losses into account, but for practical purposes, we can consider that the current is approximately halved, so 1 Amp. For comparison, the AC-9VS power adapter can supply 9 Volts at 2 Amps (18 Watts). The boost cable delivers sufficient power to supply the camera for moderate power demand stills shooting, and for grip charging of one battery.

If grip battery charging of two batteries is attempted, the boost cable will demand more than the power bank's (typical) 2 Amp total current limit, and the boost cable itself, will be pushed outside its operating limits. This will cause the boost function to fail, with inability to achieve the required 9 Volt supply. To reset the system, the boost cable has to be disconnected, and the reconnected, with the appropriate reduction in current demand. To avoid this problem, it is recommended that one of the batteries be removed from the grip, so that if the grip goes into charging mode, the limits of the boost cable are not exceeded. Unlike power delivered via the camera body's USB socket, input through the grip's DC socket can power the camera, even without any batteries inserted (camera or grip). Again however, keep in mind the boost cable's limit of about 10 Watts of power, whereas for highest level of performance, more than 18 Watts (AC-9VS power adapter plus at least one battery) may be required.

Section - E

LITHIUM-ION BATTERIES

The NP-W126S and NP-W126 batteries are constructed of two series-connected metal-can type prismatic lithium-ion cells, together with a built-in power management board, all of which is sealed in a polycarbonate case.

(In what follows, "lithium-ion" will usually be abbreviated to "Li-ion"). The exact chemical composition of the NP-W126S battery is proprietary information. However, some information can be gleaned from Safety Data Sheets, lodged for the purpose of compliance with international transport regulations.

The exact transition metal component of the positive electrode is not openly specified, but the candidate metals are: Co, Mn, Ni, and Al. In what follows, specific information that was available from Fujifilm and from Panasonic Energy in Wuxi (the battery's normal manufacturer), is supplemented by information which applies to Li-ion batteries in general.

BE CAREFUL - NOT FANATICAL
The following information is intended to assist you rather than burden you. In real life practice, it is not possible to follow all of the best advice, all of the time. We should differentiate between occasional sub-optimal battery treatment, and habitual misuse. Since the battery has a limited life regardless of how carefully it is treated, there is little point in becoming obsessive-compulsive in regard to maximising battery life.

BATTERY STATES AND PERCENTAGES
There are two commonly quoted Li-ion battery states that may both be expressed as percentages. One is the battery's State of Health (SoH), and the other is the battery's State of Charge (SoC).

STATE OF HEALTH
State of Health is a ratio of the battery's present capacity for storing energy, compared to the battery's original capacity at the time of manufacture. SoH speaks to whether the battery is, viable for continued usage, or approaching the state of being considered a dead battery. The expression of SoH as a percentage is more conceptual than practical, because the user usually doesn't have an instrument to directly measure the SoH, and it is typically inferred from the battery's age and performance. By definition, the battery's capacity when new will be 100%, but this percentage will decline with time and usage. We are typically interested in the range from 100% to 80%, because when the SoH reaches a conceptual 80%, there is a noticeable fall-off in battery performance. For the photographer, this fall-off generally manifests as a reduced number of shots per charge, and around 80% is a typical point at which we might consider withdrawing the battery from primary service, and replacing it.

STATE OF CHARGE
State of charge is a ratio of the battery's present actual deliverable energy, compared to its present potential for holding deliverable energy (which is, of course, largely dependent on the battery's SoH). State of Charge is what is displayed by the camera's battery level indicators. When fully charged, the SoC is 100%, but when "flat", the SoC would be reported as 0%. Keep in mind that 0% is relative, and does not mean absolutely zero energy. Li-ion batteries cannot tolerate being at very reduced voltages, and so a certain amount of electrical potential must always be reserved, to keep the battery in a safe electro-chemical state. This reserve is handled automatically by the camera's power management system, and generally need not be a concern of the user. But, as a consequence of this reserve, not all of the battery's electrical energy is available for use by the camera.

To summarise, a flat battery will have a low State of Charge (say 0%) and the remedy is to re-charge it, while a dead (or dying) battery will have a low State of Health (say 80%) and the remedy is to replace it.

BATTERY LIFE EXPECTATION
As a general rule, Li-ion batteries do not suddenly "die", but rather, they show a gradual decline in capability. Within the context of that decline, we can broadly identify a transitional phase when the battery's performance goes from meeting expectations to failing to meet expectations. We can consider the service period up to the "failure to meet expectations" point, the life of the battery. The Li-ion battery's life inevitably declines due to two processes known as calendar fade and cycle fade.

CALENDAR FADE
Calendar fade refers to a time related decline in capacity, which is independent of charge-discharge cycling, and which even affects batteries that are not being used. (Note that calendar fade is also accelerated by high temperatures, so it is beneficial for batteries to be kept cool). The commonly accepted rule of thumb is that, after 2 years, a Li-ion battery can only hold 80% of its original capacity. In general, at 80% capacity, although the battery is still usable, it is noticeably under-performing.

CYCLE FADE
Cycle fade refers to an in-service related decline in battery capacity due to repeated charge-discharge cycling. Fujifilm states an expectancy of 300 charge-discharge cycles for the NP-W126 class batteries (Owner's Manual, p. 274). Again, capacity falling to 80% is the criteria for determining expected cycle numbers.

BALANCED USAGE
If we try to balance these fade processes by aiming for the calendar fade endpoint and the cycle fade endpoint to coincide, (300 cycles distributed over a period of 24 months), we are looking at roughly 3 charge-discharge cycles per week, for a single battery. We can consider this as a hypothetical standard-usage-density for the purpose of determining whether the battery is being over or under utilised.

NEW BATTERIES
The Owner's Manual (p. 28) states: "The battery is not charged at shipment." New batteries are delivered with approximately 30% SoC. This is partly to extend service life by keeping the battery in a preferred storage state until the user has taken delivery of the battery, and partly due to transport regulations, (specifically, transportation by cargo aircraft under UN3480, Class 9 Dangerous Goods category, with state of charge not exceeding 30%), since Li-ion batteries are safer (less likely to enter a thermal-runaway condition if subjected to elevated temperatures) at a lower SoC. The new battery may have to be charge and discharge cycled about three times before it gives normal charge and discharge behaviour. This is because Coulombic efficiency (the ratio of the total charge extracted from the battery to the total charge put into the battery over a full cycle), improves with cycling. Previous to the battery being cycled, its Coulombic efficiency may have been between high-80's to mid-90's percent. After a small number of cycles, it can approach 99% or higher. Some batteries have already been cycled by the manufacturer, before delivery.

DETRIMENTS TO SERVICE LIFE
The following situations or conditions should be avoided to ensure that the Li-ion battery is not un-necessarily stressed.

• Avoid high temperatures (should not be subjected to > +45°C or +113°F)
• Avoid ultra-fast charging (Rate of charge greater than 1C)
• Absolutely avoid charging at temperatures below 0°C.

CHARGING
Li-ion batteries are charged according to the constant voltage (CV) / constant current (CC) method. The charge process has two main phases. In the first phase, the current is constant, at a value determined by the selected C-rate, the voltage steadily climbs, and the increase in charge, over time, is linear and rapid. In the second phase (saturation phase), when the maximum charge voltage (8.4 Volts) has been reached, the voltage becomes constant, the current drops rapidly, and the increase in charge, over time, becomes non-linear, and slower. If charging is being monitored, the rapid drop in current is a good indicator of the position in the charge process. Charging terminates when the current drops below a threshold (0.1C is typical).

CHARGE RATES
Battery charging times are mainly dependent on ambient temperature and charging rate. Charging rate, or C-rate, is the expression of charging current normalized against battery capacity. For example, when charging with a rate of 1C, a 1200mAh capacity battery would be charged at a current of 1200mA, and would be fully charged in 1 hour (theoretically). Note however, that a rate of 1C is considered to be higher than optimal, and the recommended fast charge rate is 0.7C. Because very high rates of charging are detrimental to the long-term condition of the battery, high-rate charging is usually terminated earlier in order to avoid detrimental effects. As a consequence, the available capacity changes per different C-rates, with the higher C-rates typically producing slightly less available capacity.

CHARGING TIMES
The X-T3's different charging methods use different charge rates, and as a result, have different charging times. Of the available charging methods, charging via the grip uses the highest rate, and can charge two batteries simultaneously. Charging via the camera body's USB port (if not using USB PD or "Power Delivery") has the lowest charge rate and, although the slowest method, is probably the best for the battery, both in terms of available capacity, and long-term battery health.

If using an external power monitor, be careful not to confuse input current with charging current. You can avoid this problem by working in Watts (current x voltage). For a USB input, the voltage will be 5 Volts (even for USB PD). For charging, the voltage will be 8.4 Volts. USB PD is explained more thoroughly in Section H, about the X-T3 USB Port.

PARTIAL CYCLING
Li-ion batteries do not have any significant memory effect, so there is no absolute requirement for Li-ion batteries to be fully-cycled on a regular basis. They can be partially cycled, but be aware that the various part-cycle patterns can differ in their beneficial or detrimental contribution to long term battery health. Ironically, (and different from many other battery types), the "fully charged" state is more stressful to the Li-ion battery than lower states of charge, and leaves the battery more susceptible to electrolyte oxidation, which is cumulatively detrimental to its life, each time the fully-charged state occurs. Therefore, full cycling (fully charge, then fully discharge), is preferable to "top-up-to-full" partial cycling, because, in the long run, it results in fewer instances of being "fully charged".

If you know that a shoot will only require a small number of shots, (perhaps a couple of dozen), then there is no problem with giving a discharged battery a shorter charge , say 40 to 60% of full capacity. Routinely charging the battery to slightly less than full capacity (90% would be ideal), has a beneficial effect on battery longevity. However, the reduced number of shots per charge is not acceptable to most photographers.

VOLTAGE LIMITS FOR CHARGE AND DISCHARGE
Automatic chargers should implement protections against over-charging, and the camera should implement protections against over-discharging. The battery also has its own internal protective circuit to guard against over-discharging. Limits are according to the following significant voltages:

Although there are automated systems in place to guard against over-charging and over-discharging, poor usage practices can effectively put the battery slightly into the over-charged / over-discharged state. Slight over-charging can result from repeatedly putting an already fully charged battery back on the charger. Slight over-discharging can result from repeatedly turning on again, a camera that has displayed the battery empty sign and automatically switched off.

TEMPERATURE LIMITS
Li-ion batteries are noted for their wide range of operational temperature compared to many other battery types, however, they are very sensitive to temperature beyond that operating range.

As temperatures become elevated, initially the battery sustains internal damage which impacts its long-term performance, then at very high temperatures, the battery starts to sustain damage which can pose serious safety risks. Li-ion batteries contain flammable electrolyte that may vent, and spontaneously ignite when subjected to temperatures above +150℃ or +300°F. When ignited, Li-ion batteries can burn rapidly with flare-like burning effect, and may ignite other batteries in close proximity.

VOLTAGE STABILISATION
After a full charge, the open-circuit voltage of the battery (as checked with a multi-meter) will decrease rapidly in the first 10 minutes and then gradually over the next few hours before stabilising. If you intend using voltage as a guide to battery condition, rest the battery for 90 minutes after charging, before measuring the voltage. The stabilised voltage is a better indicator of SoC than the voltage measured immediately after charge termination, and you are likely to get better power metering by the camera if you begin using the batteries after they have stabilised. This supports the practice where, if you have to charge batteries for a shoot, it is preferable to charge them the night before the shoot, rather than immediately before the shoot.

MEASURING BATTERY VOLTAGE
If you have the requisite background knowledge, and are comfortable with using a digital multimeter (DMM), you can use the battery's open-circuit voltage as a surrogate for battery state and condition. Since these measurements do not assess the battery under load, they cannot account for load related voltage drop, however they are useful in giving further information for battery assessment and comparison. It should be noted that instantaneous voltages during charging, and instantaneous voltages during discharging display hysteresis. That is, they follow different curves, showing discrepancies in the region of up to half a Volt, with lower voltages presenting for the discharge curve. Therefore, voltages during charging and during discharge are not suitable for comparison.

When doing these static measurements on the battery, the only contacts of interest will be the positive and negative contacts. For measuring the open-circuit voltage, set the DMM to DC voltage measurement, and make contact with the probes for just enough time to get a stable reading. Measurements should be made to the nearest tenth of a Volt.

NP-W126 BATTERY CONTACTS
The NP-W126 class batteries have four gold-plated electrical contacts, marked with [-], [S], [T], and [+] symbols.

The [T] contact pertains to temperature management, and should connect to an NTC (negative temperature coefficient) thermistor, with a nominal resistance of 10kΩ at 25°C (±5% or better, typical). The resistance of the thermistor drops (with a non-linear output) as temperature increases. [To give an example: The NP-W126S battery was temperature stabilised at the room temperature of 15°. The resistance reading from the thermistor was 13.5 kΩ. Then, the battery was placed under the armpit for 5 minutes, to warm it. After warming it, the thermistor reading was found to have dropped to 9.5 kΩ]. The thermistor allows temperature monitoring while charging. Li-Ion batteries typically increase 5°C (9°F) in temperature during charging, as a normal consequence of the chemical process involved. But, the battery should not be allowed to increase more than 10°C (18°F) during charging, nor is charging allowed at more than 45°C, or less than zero°C, in order to avoid shortened battery life, lithium plating at the anode at sub-zero temperatures, and over temperature hazards such as battery swelling, venting, and thermal runaway.

When attempting to charge the NP-W126 class batteries, in the X-T3 camera, or either of the two Fujifilm chargers, if a resistance indicating a temperature within the safe range is not seen at the [T] contact, then charging is not initiated. (This safety function is also implemented on the Nitecore FX1 USB charger). On non-OEM batteries, the [T] contact is usually just connected to a fixed 10kΩ resister (meaning that it always signals the temperature as OK, even if it is outside the acceptable limits). This allows the batteries to be charged, without adhering to the safe charging temperature protocols.

The purpose of the [S] (probably standing for "Status" or "System") contact is not openly documented. The [S] contact most likely accesses a simple system indicator, that gives battery information by whether or not a measured resistance exceeds certain thresholds. Such a method is expandable over time, so that if a new further improved battery became available, another higher resistance threshold can be added to the system, to indicate that battery. Note that the X-T3 camera differentiates between "S" and "non-S" type batteries, by interrogating the resistance on this [S] contact.

SELF-DISCHARGE
Typical self-discharge rates for Li-ion batteries (at a temperature of about 20°C) are 5% in the first 24 hours after charging, and then 5% per month (this monthly five percent is made up of approximately 2% intrinsic loss, and 3% due to drain by the battery protection circuit).

As a rule of thumb, the self-discharge rate doubles with every 10°C increase in temperature.

PLANNED DISCHARGE
Sometimes, we may wish to intentionally either partly or fully discharge a battery, for example, for testing purposes, or in preparation for storage. The X-T3 camera does not provide a specific discharge function (Some cameras do, for example Samsung NX1). For the X-T3, the best way to discharge the battery is through normal usage, just by taking photographs or video. There may be situations where your purpose is only to take the battery's SoC just out of the fully-charged zone (one of the more stressful states of battery condition). For example, you may have charged the battery in anticipation that it would be used, but it turns out that you won't be needing it, and the battery faces an extended period of non-use.

In such a case, you can slightly discharge it by the following method. Put the battery in the currently assigned discharge position (the left-most position if using the battery grip), attach the supplied EF-X8 shoe mount flash unit to the X-T3, and take a few shots using the flash. The EF-X8 has to be used, since it draws its charge power from the X-T3 batteries. (Incidentally, occasional use of the EF-X8 flash, is good for the X-T3's flash capacitor, and helps to keep it "formed"). Another method is to take some video at a high frame rate and resolution (it doesn't need to be 4K video). It is not recommended that you discharge by taking long duration continuous-shooting bursts using the mechanical shutter, because this will cause unnecessary wear-and-tear on the shutter, which although rated at several hundred-thousand actuations, never-the-less has a limited lifetime.

STORAGE
Conditions of storage (an extended period of non-use) have an impact on the life expectancy of the battery. The most significant factors are, the battery's State of Charge (SoC), and the ambient storage temperature. A Li-ion battery's state of least stress is about 40% SoC at 15°C (59°F). This is represented by 2 bars on the X-T3's battery level indicator.

DOWN TIME
If the battery will not be used for several days, or even a week, this period can be considered normal down-time, rather than a storage period. The battery can be left in its present state of charge, although leaving it in a fully charged state is not ideal, and should not be a target for a regular down-time state.

SHORT-PERIOD STORAGE
If it is estimated that the battery will be in a storage condition for a few weeks, "half-charged" is an appropriate level. However, it is also OK to leave the SoC at an effectively "flat" level. A battery which has just gone flat (according to the camera), is still well above any damaging over-discharge voltage. An ambient temperature of +15°C is optimal, but since the period of non-use will be short, a storage temperature in the range -10 to +40°C is OK.

LONG-PERIOD STORAGE
If it is estimated that the battery will be in storage for a period of months (this could happen if you were going to be away from home for an extended period of time, and you are taking a different camera with you), it is recommended to have the SoC of the stored battery at 40 - 50%, indicated by between 2 or 3 bars on the X-T3's battery level indicator. This places the battery in a low stress condition, but also allows for inevitable self-discharge (about 5% per month) to take place, without the battery over-discharging. The battery should not be stored in the camera, due to further discharge by quiescent current. (Quiescent current flows due to the camera awaiting any wake-up signal from the power switch, and also from powering the clock-calendar). An alternative method of assessing a battery's readiness for storage is by measuring its voltage. A battery in good condition will have a stabilised open circuit voltage of about 7.6 Volts when its SoC is about 40%.

If initially stored at 40% SoC, after about 8 months the battery may be close to flat, so it would be good if the stored battery could be given a part charge (back to 40 - 50%), say about every 3 - 6 months. At any rate, a battery should be charged at least once per year. A storage temperature of +15°C is optimal, but up to +25°C is acceptable, however it is not recommended to store the battery outside the range of 0 to +35°C.

KEEPING CONTACTS CLEAN
Keeping the battery's gold-plated contacts clean can help attain optimal charging and usage conditions. Contacts can become dirty from inadvertently touching them, or simply by the deposition of air-borne grime (particularly in cities, where the presence of diesel fuel particulates and other pollutants can be significant). A cotton-tip is useful to buff the contact surface. No liquid or solvent should be used.

Keep in mind that there are numerous contacts in the power supply chain, and they all need to be kept clean. However, be very careful not to catch and bend any spring contacts.

IDENTIFYING INDIVIDUAL BATTERIES
For the purpose of battery management, it is useful to be able to identify each individual battery, by labeling them. No stickers should be attached to the sides of the battery, due to the possibility of jamming in the battery chamber. A convenient place to write (using a fine tipped permanent marker), a number, letter or symbol for individual battery identification, is the orange orientation patch (square or circle) at the end of the battery. The manufacturing year and month code letters are convenient identifiers. Unless several batteries were purchased at the same time, and they came from the same production batch, the production codes are likely to be unique, for each of your batteries.

If you have to use non-OEM batteries, you can put a small sticker in the same position as the NP-W126 class battery's orange orientation patch. Since you probably won't know the production date of the battery, you can arbitrarily assign it a production date three months prior to the purchase date, (this allows for some shelf time with the vendor, before purchase). You can give it year and month code letters, according to the Fuji system, so that any management records follow a consistent method.

DETERMINING THE BATTERY 'S END OF LIFE
A battery is effectively dead when the photographer rejects it due to poor performance. A battery that has been used properly does not suddenly cease working, but it does eventually reach a point where its performance no longer meets the requirements of the photographer. This point will differ slightly from person to person, depending on their usage style and workload demands. Specific signs of a dead or dying battery are:

• Uncharacteristically long or short charging times
• Very rapid self-discharge
• Noticeably decreased number of shots per charge.

SoH LOOK-UP-TABLE
Based on the typical signs of a dead or dying battery, the photographer will develop a feeling about how a particular battery is doing. However, this type of assessment can be very subjective. A more objective criteria of the battery life condition (State of Health - SoH) can be obtained from the stabilised (90 minutes after-charge) open-circuit voltage. It is not possible to give a universally applicable look-up-table (LUT), because battery usage routines (as well as user expectations), and local environmental conditions, will cause variation in the typical voltages reflecting the various states. However, it is possible to compile your own personal LUT over time, if you are prepared to take measurements and keep records. A SoH look-up-table, may be similar to this:

This method is useful if you want to keep records, for comparison, of battery condition at regular intervals, because it yields a number.

BATTERY AUDIT FORM
A convenient way to keep records of battery condition is a battery audit form. This could be either on paper, or a computer spreadsheet. On the form, you record the open circuit voltage (90 minutes after charging), of each battery.

This is done at regular intervals; three monthly (that is, four times a year), would be an appropriate interval. Just do it sometime during the designated month - it is not necessary to do it on a specific date. The form also allows you to record the reaching of significant voltage thresholds (based on the SoH look-up table).

A PDF file of the audit form can be downloaded here: Battery-Audit-Form.PDF

PRIMARY AND SECONDARY BATTERY SERVICE
Batteries that are beyond the two year or 300 cycle stage, although no longer in their prime condition, are still useful. While the best batteries are kept for operating the camera at its top performance (primary service), the aged batteries can be assigned to secondary service tasks. Such tasks include:

• Back-up batteries
• Batteries for short or low shot count sessions
• Hold-over batteries

Hold-over batteries are useful if you recharge all batteries directly after a shoot, in readiness for whenever the next shoot will occur. If the camera is left unused for days or weeks, the first battery in the discharge sequence will lose some of its charge (due to quiescent current, waiting for power-up signal, and maintaining the clock and calendar system). That same battery would maintain more of its charge over the same period of time, if not left in the camera. To avoid this "stand-by" discharge of the battery, when you are not using the camera, you can replace the first battery with an old battery, and just swap in the newer (still well charged) battery, before the shoot.

JUST IN CASE vs JUST IN TIME
"Just in case" and "Just in Time" (JIT), indicate two different approaches to what "triggers" you to recharge your camera batteries. Should you recharge them immediately after a shoot (so that they are ready to go), or should you leave them in their post-shoot state, and recharge them just prior to the next shoot? There is no universally correct answer, because it will depend on your usage style, workload demands, and also your ability to know in advance when the next shoot will be, or even to exercise your own discretion about when shoots will occur. Keep in mind that, when a Li-ion battery has gone flat during a shoot, there is no problem leaving it in that state for some days, or even weeks (just let it have some "down time"). A Li-ion battery is very different from a lead-acid car battery, which should not be left in a discharged state. However, as to the long term affects on battery life, it is probably more beneficial to, where possible, let the immanence of usage be the trigger for recharging (just in time), rather than letting the conclusion of usage be the trigger for recharging (just in case). This is because, with charging directly after the shoot, if you wait some time before the next shoot, the battery has been left longer in a fully charged state (not optimal for battery longevity), and you are likely to give the batteries a top-up charge before the next shoot anyway. This results in more charging than is absolutely necessary. Furthermore, Li-ion battery service life benefits from sustained (many hours to days) relaxation periods following discharge and before re-charging.

BATTERY CASES
Battery cases are useful in order to protect against accidental shorting of the power terminals, and give a convenient means of distinguishing between charged and discharged batteries. Also, in accordance with IATA regulations, pouches or cases are necessary if spare batteries are to be carried (in carry-on baggage only) while traveling by air-transport. New NP-W126S batteries, when purchased as an accessory, are supplied with a plastic soft pouch.

However, if you would like a hard case, those designed to fit the Nikon EN-EL9 battery, are suitable (although slightly longer than necessary). You can cut some dense (non-conductive) foam plastic to fill the extra length, and stop the battery from rattling in the case. The internal dimensions of any suitable battery case, need to be at least 47.5 x 36.5 x 16 mm.

For working in harsh environments, sealed weather-proof cases are also available.

IDENTIFYING CHARGED / DISCHARGED BATTERIES
If spare batteries are kept in a pouch, or battery boxes, a simple method of distinguishing between charged and discharged batteries, is by inserting the batteries with the contacts facing either inwards or outwards, to signify charged or discharged. Alternately, if you use many batteries, you can have two battery pouches, one for charged batteries, and the other for discharged batteries.

LI-ION FIRE HAZARD
If a Li-ion battery develops an internal short-circuit, this can be the prelude to a thermal-runaway event that eventually causes the battery to rupture or vent, and spontaneously ignite. Other triggers for catastrophic battery events include: faulty charging, accidental short circuit by contact with metal objects, use of the camera or batteries outside of allowable limits, and heavy trauma to the camera. The fuel for the ignition is the electrolyte content of the battery, rather than lithium metal. Although lithium metal reacts violently with water, lithium-ion batteries, contain very little metallic lithium. As a consequence of the sparse metallic lithium content, water is a suitable and recommended extinguisher for burning Li-ion batteries, such as the NP-W126 types. There are two goals in extinguishing a Li-ion battery fire: First, to extinguish the initial fire, and second, to cool the immediate surroundings to avoid the ignition of other Li-ion cells. It should be remembered that a single NP-W126 type battery contains two Li-ion cells, so the X-T3 camera and grip (3 batteries in total) holds 6 cells, and each one will ignite in series (with a delay of between several seconds up to several minutes between each ignition), if the local temperature is not significantly lowered. Water is the best medium for lowering the temperature. However, covering the extinguished batteries, even with ice cubes, is not recommended, because it tends to form an air pocket which traps and retains the heat, leading to re-ignition.

Section - F

POWER MANAGEMENT SETTINGS

Mirrorless cameras, such as the X-T3, are inherently more voracious for power than DSLR's. The specific difference in power requirements is the mirrorless camera's use of an electronic viewfinder (EVF), or continuous use of the LCD monitor. The key to getting power consumption that approaches that of the DSLR, is to configure the EVF and LCD monitoring system, so that they are not turned on more than they need to be.

VIEW MODE SETTING
The most power efficient View mode option is "EVF ONLY + Eye Sensor", because it results in the viewing system being on for the least possible time. "Putting your eye to the viewfinder turns the viewfinder on; taking it away turns the viewfinder off. The LCD monitor remains off". The view modes can be cycled through by pressing the view mode button on the right side of the EVF housing.

AUTO POWER OFF SETTING
Try to set the Auto Power Off function to the shortest interval that you can comfortably work with. Wake-up from automatic power-off is achieved in less than one second by simply half-pressing the shutter button.

POWER MANAGEMENT MENU
Auto Power Off and Performance settings are accessed through the Power Management sub menu of the Camera's Set-Up menu. For convenience, the Performance (Boost) setting can be assigned to one of the function buttons. However, this is not necessary when the optional grip is used.

When the grip is attached, the "Performance" menu option, is greyed out, and unavailable, (to avoid selection conflicts) because the grip has its own dedicated performance (normal or boost) switch.

BOOST MODE
Unlike the X-T2 and X-H1 cameras, the X-T3 is able to realise top performance even without the optional battery grip. The high performance mode is called boost mode. When the highest performance is not needed, the camera can be set to Normal mode. In Normal mode, to conserve battery power, after ten seconds of inactivity (no button, dial, or touchscreen activation), the displays revert to a stand-by mode (low brightness, and very slow frame refresh rate). The display leaves this stand-by mode if there is a control activation event, or if the power mode is switched to Boost. There are no menu options for modifying this behaviour. However, if you are not using functions that that take a high power drain (continuous auto-focus, continuous high-rate stills shooting, and high resolution video), then leaving the camera in Boost mode should not produce any significant run time deficit.

According to the advisory message displayed when non-S type batteries are loaded, "Boost mode function is restricted". The exact restrictions, for this situation, are still being compiled. (I will update this guide, as further information becomes available).

Section - G

EXTERNAL CHARGERS

BC-W126S / BC-W126
The release of the X-T3 was accompanied by the introduction of a new battery charger. The newer BC-W126S is the charger generally supplied with the X-T3 camera, although, the Owner's Manual (page xix) states: "A BC-W126 battery charger may be supplied in place of the BC-W126S in some countries or regions". The two chargers are interchangeable, and either charger can be used for either battery (NP-W126 or NP-W126S).

The two chargers differ in two main points: The method of connecting to the mains supply, and the slightly increased maximum output current by the BC-W126S. (Does the newer charger differentiate between the older NP-W126 and the newer NP-W126S batteries, when charging them? I don 't know yet, but keep in mind that the two battery types have a different resistance level on their [S] contacts, so the charger may differentiate, and charge them slightly differently. But, that's pure speculation. I will try and test this when I make a break-out box for the charger.)

NON-OEM CHARGERS
Some non-OEM chargers can deliver functionality and flexibility not available from the standard supplied charger. Beyond cost, you should consider how the charger fits in with your workflow and approach to photography. It is also important to remember that the quality of the charger can have a significant effect on short-term and long-term battery performance and service.

UNEXPECTED INTERACTIONS
Power banks utilise a voltage converter circuit to change the battery voltage to the required USB supply voltage. Power is lost due to the conversion process, so it is typical for power banks to turn off the conversion circuit, if the power bank senses that the connected device no longer requires power. (The power bank will assume this if current draw falls below a certain threshold). At the same time, some chargers (typically, "smart" chargers), may momentarily suspend charging at regular intervals, in order to take measurements of the battery's state of charge. If the power bank's checking of the current flow, and the charger's checking of the charge state happen to coincide, the power bank may momentarily shut down. After the smart charger's state of charge check, the power bank will sense the charger's need for power, and power up again. This gives the unexpected behaviour that the pair of devices "power off" momentarily, and then resume operation. The momentary power interruption does not affect the charging of the batteries, but it does have the effect of causing the charger's count of accumulated milli-Amp hours (mAh) to reset back to zero, each time a power interruption occurs. I have experienced such an effect when powering the Nitecore FX1 with some power banks (including Tomo). However, if you place a USB power monitor in-line between the power bank and the charger, it can sometimes act as a buffer, so that power interruptions tend not to occur, and the effect of the mAh count resetting is avoided.

OVER-TERMERATURE PROTECTION
One very important factor, when considering non-OEM chargers, should be, whether the charger implements any kind of temperature monitoring, while charging. This will mean, either the ability to monitor the NP-W126S or NP-W126 battery's thermistor (on the battery's [T] contact), or the charger having its own built-in temperature sensor. Over-heating the batteries while charging will produce cumulative damage to the batteries (noticeable as as a decline in the battery's performance, or as swelling, or venting of electrolyte reduction gases). Two third-party battery chargers that are known to implement battery temperature management are, the JJC DCH-NPW126 dual slot USB charger, and the Watson Duo Charger, dual slot AC charger (both chargers utilising in-charger battery temperature sensors). The Nitecore FX1 dual slot USB charger (utilising a third battery contact to monitor the battery's thermistor output), reports the internal temperature of the genuine Fujifilm batteries (not of non-OEM batteries, however), and it should be noted that it does not terminate charging if the temperature exceeds the allowable temperature range - the user must do that.

Note that if the battery is non-OEM, and does not implement a working thermistor, then a charger's thermistor monitoring function will be ineffective, since there is no genuine temperature information to monitor (only the battery's fixed 10kΩ output by the [T] contact, which flags a "within acceptable temperature range" status, required by the Fuji charger before it will initiate charging).

Section - H

X-T3 USB PORT

The X-T3 camera has a USB type-C (USB 3.1 Gen 1) connection port. As well as its data transfer function, the port can also be used to input 5 Volt power for charging the battery in the camera body, or to assist powering the camera's operation.

MODE SELECTION
Because the X-T3 has tethered shooting functionality, connection of a USB cable can trigger unexpected camera behaviour, if the Set Up Menu's "PC Connection Mode" setting is not appropriate. How the 5 Volt supply is utilised depends on camera mode (off, shooting, or playback), as well as the PC Connection Mode menu settings. If not tethering to a computer, a relatively trouble-free setting is "USB Card Reader" mode.

CONNECTOR TYPES
The USB socket accepts a USB type-C plug. However, depending on the type of device used for charging, the cable could be either a USB type-C to type-C, or a USB type-A to type-C cable.

According to USB standards, the X-T3 is considered a high power device, since it requires at least 500mA from the USB supply.

Since all of the USB standards from 2.0 onward can deliver at least 500mA (composed of an allowed maximum of 5 x 100mA load units, as defined under the USB standard), most USB compliant outputs meet the X-T3's charge requirements. It is best to use the highest current-capability port for powering or charging. If the device manufacturer has implemented port colours, they can be a convenient method of differentiating between the power capabilities of different type-A port options, on a desktop or notebook PC. Port colours are not mandatory, however, members of the USB Implementors Forum (USB-IF), tend to assign the colours consistently. Of course, if the power output port is a type-C port, you can assume that it is USB 3.1 standard.

If you have previously been working with USB 2.0 and 3.0 charging methods, and using type-A and micro-B connectors, the X-T3's adoption of the type-C connector does not mean that your previous charging system needs to be replaced. As long as the system terminates in a type-C connector, for connection to the X-T3, you can continue as before.

It should only be necessary to acquire a new type-A to type-C cable, or even a micro-B to type-C adapter, if a charger has a fixed cable ("hard-wired captured cable"). These plug adapters can also be used on legacy cables (earlier generations than type-C). The converse scenario might occur if you have acquired a USB power supply with fixed type-C cable, and you want to charge a power bank, or use a USB battery charger, that only has a Micro-B input port. In this case, a type-C to Micro-B adapter with the genders reversed can be used to make the connection for charging.

Please be very careful. These adapters are very small, and therefore dangerous to leave within reach of infants and small children, who might put them in their mouth, with the risk of choking.

It should be noted that the USB type-C standard implements two Control Channel pins (CC1 and CC2) on the type-C connector, and these are used to establish and manage the Source-to-Sink connection. Since legacy cables and connectors do not implement these Control Channel lines, attaching type-C adapters to a legacy cable will not convert it to a "full featured" type-C compliant cable. However, it can still produce a functional USB power transfer cable.

USB "POWER DELIVERY"
What happens if the X-T3 is connected to the USB PD (Power Delivery) port of a computer, power bank, or to a USB PD power supply? We know from experience that if the X-T3 is connected to a USB PD power supply with a hard-wired captured cable (so that there is no doubt that the cable is PD aware, compliant, and capable of conducting high currents), the X-T3 will draw 5 Volts at up to 1500mA for charging, or operation in video mode. In stills photography operation, the current draw is considerably less. In contrast to this, when the same USB PD power supply, is used to charge a 20000mAh PD power bank, the power bank draws 9 Volts at 2000mA.

Because the X-T3 has a Type-C port (which people often associate with PD), and because Fujifilm has recommended external USB power via the Anker PowerCore powerbanks (which support PD), there might seem to be the implication that the X-T3 supports elevated power levels via the PD functionality. However, as far as I am able to establish, the X-T3 does not require or negotiate elevated PD power levels (that is, power above the PD default), although it is compatible with USB systems that do support PD. So, if a charger, power bank, or PC conforms with the general USB specifications, it can be used to supply USB power to the X-T3, whether the device supplying the power supports PD or not. The following (printed in red) is simply to explain how PD works, and why we can say that the X-T3 does not negotiate elevated power levels.

USB Power Delivery (PD) is designed to co-exist with standard USB Battery Charging implementations. The USB Power Delivery protocol requires the following steps: Connection, Default Operation, Discovery, Negotiation, and Contract Operation. When a USB host and device are first connected, the initial operating conditions are the USB Default Operation, which assumes a DFP (Downstream Facing Port) supplying vSafe5V (a voltage level of 5 Volts, which is safe for all USB devices) over the VBUS line, and a UFP (Upstream Facing Port) consuming power from the VBUS line. In the case of USB PD compliant equipment, once these default conditions are set, a Discovery process can begin, if the connecting cable meets requirements. Discovery comprises the exchange of structured VDMs (Vendor Defined Messages) resulting in identification of the Port Partner, its supported SVIDs (Standard / Vendor IDs) and Modes. After the Discovery process, power Negotiation begins. The Source (power supplier) advertises its capabilities, and the Sink (device which will consume the power) requests one of the advertised capabilities. Then, the Source acknowledges the request and alters its output to satisfy the request. The result of this process is a Contract for power delivery/consumption between the two port partners. The contract specifies both power level and direction between the Port Pair. Typically, the contract continues until the ports are disconnected.

Cable specifications are an important part of the USB PD protocol, because, as well as the power source being able to supply the required power, a connected cable must also be able to carry that supplied power. Higher power requires a higher specification cable, for instance, heavier gauge conductors. Standard Type-C cables (with no built in circuitry) should support up to 3 Amps of current by default. But in order for a USB PD compliant source to advertise capabilities greater than 3A, the Type-C cable must be an Electronically Marked Cable Assembly (EMCA). The electronic marking is accomplished by embedding a USB PD controller chip into the plug at one or both ends of the cable. The cable controller stores configuration data related to the identity and capabilities of the cable. Electronic marking is needed in a Type-C Cable when VBUS current of more than 3 Amps is required. Of course, an Electronically Marked cable will be more expensive than the corresponding un-marked cable. The benefits of an Electronically Marked cable are not relevant for the X-T3 camera, since it does not require current at higher levels than the 3A default. The next step up in current rating is 5A, and since 5 Amps at 5 Volts is 25 Watts, that already exceeds the X-T3's 18 Watt power rating. The simple "un-marked" type-C cables are sufficient for the X-T3's power requirements. Importantly, after the setting of the USB Default Operation, if the PD protocol cannot be established, then the power remains at the default vSafe5V , which should mean there is no risk of damage to equipment. In this way, interoperability between PD capable equipment and legacy USB equipment and cables, is maintained.

In practical terms, the significance of USB PD for the X-T3 camera seems to be the ability for the camera to draw 1500mA at 5V (even with just a standard type-C cable), compared to the typical 900mA at 5V from the USB 3.0 / 3.1 bus. This increase in current represents a modest improvement. Note however, the USB 3.0 Dedicated Charging Port (DCP), could already deliver 1500mA. Although the USB PD standard allows, in principle, power delivery up to 100 Watts, the X-T3's ability to consume power is limited, by its highest battery-safe C-rate while charging, and in operation, by its maximum working temperatures, since more power produces more heat. Increased heat, without a corresponding ability to dissipate heat at a higher rate, would be a typical precursor to camera lock-up events. Remember that the X-T3 is rated at 18 Watts. So, even with USB PD, do not expect the X-T3 to be able to benefit from more than 5 Volts at 3 Amps, maximum (15 Watts).

In summary, it would seem that the X-T3, even in a fully PD compliant connection context, does not exploit the possibility of negotiating elevated power levels through the PD protocol, probably because the camera does not need those elevated levels.

The camera is, however, able to gainfully utilise the increased default power level offered by PD capable equipment (maximum current of 3000mA, rather than 900mA), and this is why connection to a PD capable port (marked with the letters "PD"), is both advantageous, and preferable to connection through a standard port. If your goal is to get maximum and continuous power for video production, an alternative option is to use V-Mount batteries with D-Tap (as explained in Section J - "DC Coupler").

USB HUBS NOT SUITABLE
The Owner's Manual (p. 33) states: "Connect the camera directly to the computer; do not use a USB hub or keyboard." Typical USB bus powered hubs cannot be used since, although they draw five load units (100mA each USB 1.0/2.0, or 150mA each USB 3.0), 1 unit is used by the hub controller, and the remaining 4 units are distributed among the hub ports (1 unit each for a 4 port hub). The available current from a hub port could be as little as 100mA, and probably not higher than 200mA, which is not sufficient for the X-T3's charging requirements. This limitation on current supply from hubs may not translate to USB PD hubs, since the current supplied at each hub port can be negotiated. We await further testing of USB hubs.

INTERNAL CHARGING
Power delivered via the USB port will charge the body battery, when the camera is switched off, however, it does not charge the grip batteries. Using the USB port, the time to fully charge a flat battery is about 300 minutes, or 5 hours, when connected to a standard USB port. This time is reduced to about 2 hours when using a PD supply port. Ability to charge the body battery via USB means that the battery can be left in the body on a quasi-permanent basis, which makes it un-necessary to remove the grip in order to charge the body battery (an inconvenience of the X-T1 camera when used with grip).

EXTERNAL POWERING
When the camera is switched on, power input via the USB port, is used to supplement the power available from the battery. Importantly, the camera cannot be operated independently (that is, without a battery installed) solely on power delivered via the USB port. Even if the USB 5 Volts is delivered at a 1.5 Amps of current, that only produces 7.5 Watts of power, which is well below the X-T3's 18 Watt power rating. However, during operation with the body battery installed, the USB supplied power can supplement the battery power, so that the battery does not run down, or is discharged only slowly.

When connecting the X-T3 for powering via the USB port, not only the USB connection settings (set via the Menu system), but also the type of cable (standard cable, charge-only cable, OTG cable, etc), as well as the equipment being connected to, determine how the X-T3 behaves. Often, the user may not be certain about the exact technical specifications of the cable they are using, or the generation and capabilities of the connected equipment. If the X-T3 senses that it is connected for data transfer, it may go into USB transfer mode (black screen, with the USB symbol in upper left corner) when it is turned on, and shooting under external power may not be possible, while the USB is connected.

In such a case, try turning the camera on before connecting the USB power supply. (In general, the USB specification supports "hot-swapping", that is, connecting or disconnecting the USB port while the device is turned on). If this does not solve the issue, you may have to explore other USB host or cable options (such as using a charge-only cable), to enable shooting with externally supplemented power.

Since firmware update version 2.00, there is a power supply icon available to indicate external power. However, the icon indicates utilisation rather than physical connection.

So, if the grip is attached, and it holds charged batteries, the icon will not initially be shown, despite USB power being connected. This is because the camera will preferentially draw power from the grip batteries. (Two charged grip batteries are able to deliver more power than the USB).

When both of the grip batteries are depleted, then the camera will start to draw USB power to supplement the body battery, and the power supply icon will show.

USB POWER SOURCES
The USB power can be delivered to the camera from a computer, an AC to USB adapter, a USB power bank, or an automobile USB outlet or adapter, etc. However, DO NOT use any unregulated voltage supply at the USB port. The maximum allowable voltage of the USB standards is 5.25 Volts (5.0 Volts +5%), and this should be considered the maximum voltage allowable at the X-T3's USB port. While the nominal USB voltage is 5 Volts, the allowed minimum is 4.75 Volts, although a device powered by the USB bus is expected to be able to operate with voltages down to about 4 Volts.

FUJIFILM AC-5VF POWER ADAPTER
This small power adapter with integrated power plug, delivers 5 Volt USB power, up to 1.0 Amp, via a USB-A socket.

The USB port offers many possibilities of internal charging, and externally supplemented power for both fixed location, and mobile setups, using a wide range of USB power options.

SECTION - I

POWER BANKS

A power bank is an external battery pack that can deliver power for charging or operation of mobile electronic devices, including digital cameras. The power bank's input and output are usually (but not always) via USB ports.

ADVANTAGES
Power banks allow portability and versatility. One big advantage is that the power they hold can be assigned to devices in an ad hoc manner (for example, to charge the camera, a smartphone, a tablet, etc, as needed). A second advantage is the ability to recharge batteries on-location, if and as necessary. Although it could be argued that there is a time and weight advantage in carrying pre-charged NP-W126S batteries, rather than a power bank and USB charger, the price difference between several genuine batteries, and a power bank, may be the critical deciding factor.

For high capacity power banks, the biggest advantage may be in powering the X-T3, in order to achieve extended running times. Note that, for the X-T3 camera, the power bank does not need to support the USB PD (Power Delivery) function, although having PD would be preferable. In general, a power bank without PD function, may be sufficient for stills photography, but for extended duration video usage, a high capacity PD power bank would be more suitable.

BRANDED POWER BANKS
It is recommended only to purchase branded (traceable registered brands) power banks, with good long term usage reviews. Unbranded power banks may state exaggerated capacities, have sub-standard internal assembly, and use un-matched cells (not matched for internal resistance) which will ultimately lead to reduced performance or even unit failure, depending on how the internal cells are connected (series, parallel, or combination).

PORT CAPABILITIES
Input ports (for charging the power bank) are typically Micro B type, or USB type-C. USB type-C ports, if PD capable, are bi-directional (marked "IN/OUT"). Not all type-C ports are PD capable. Sometimes, the type-C port is provided, simply to enable use of more recent power adapters, which may have a type-C cable. Output ports (for drawing power from the power bank) are typically USB-A, or type-C.

Since the USB Consortium maintains compatibility between different generations of USB standard, either type can be used, as long as the correct cable is available.

In the context of the X-T3 camera, USB-A ports which are designated as Quick Charge 2.0/3.0 ports, do not offer any advantage over standard USB-A ports, since the X-T3 does not recognise the QC protocols. However, the type-C ports which are designated USB PD, will allow the X-T3 to draw higher current (up to 1500mA, compared to up to 900mA drawn from a non-PD port). Power banks which offer lower capability ports (micro-B and USB-A) as well as higher capability ports (type-C PD) give an advantage of allowing the user to select charging and supply rates, by selection of the appropriate input or output ports (with the appropriate cable, of coures). Although fast charging is convenient (and sometimes necessary), lower rate charging is in the long term, beneficial to the longevity of the power bank.

EXPECTED OUTPUT CURRENT
Expect the X-T3 to draw up to 900mA of current from a power bank's standard type-A output port, regardless of the port's "marked" maximum output, which may be 1 Amp (1000mA), 2 Amps (2000mA), or even Quick Charge 3.0 (3000mA). If the power bank has a type-C "PD" (Power Delivery) output port, expect the X-T3 to draw up to 1500mA of current from that port. The nominal voltage will always be 5 Volts, regardless of the supply's scalable voltage capability. Because the X-T3 will not (based on experience) draw more than 1500mA at 5 Volts (7.5 Watts), a power bank with an 18 Watt power capability would be more than enough to supply the X-T3's power needs. There is definitely no need for a PD supply with higher power (Watts) output capability. Be careful not to confuse output current in milli-Amps (which affects power), with nominal capacity in milli-Amp-hours (which affects the running time that you get from the power bank).

When comparing the current supplied by the Type-A port and the Type-C PD port, any supply deficit (the shortfall in the Type-A port's supply) must be made up by the X-T3's internal battery. However, if the usage is non-continuous, and the camera is allowed to auto-power-off, the internal battery can recover some of that power through internal charging while in the "Off" state.

REMOVABLE BATTERY POWER BANKS
Power banks that allow the batteries to be removed (sometimes referred to as DIY power banks, because the device is delivered without batteries, which the user must supply), offer many advantages:

• You can use the highest quality batteries, (You get to choose).
• Batteries can be replaced when their performance starts to decline.
• Batteries can be "borrowed" for other purposes (LED torch, for example).
• Spare set/s of fully charged batteries can be taken, on long expeditions.

An important consideration for removable battery power banks, is whether the internal cells have their own individual channels for charging (as in the Tomo units), or if the cells are all on a single charge/discharge circuit. In power banks with individual channels, the cells do not have to be matched (for balancing), and can differ in brand, capacity, age, and even state of charge.

With such a power bank, it is possible to give the individual status of each cell. However, to maintain balance between the internal cells on power banks where cells are all on the same charging circuit, the cells must be matched (they should be the same brand and type, and even from the same batch - indicated by having exactly the same production code). Ideally, the cells should be matched to have the same internal resistance, but most users do not have the equipment needed to make this determination.

EXPECTED EFFICIENCY
Power banks normally contain an array of lithium-ion (or lithium-polymer) cells. The Panasonic NCR 18650B Lithium-Ion cells, are typical of the cell type used in many power banks. Due to economy-of-scale in their manufacture, eight of these would probably cost less than the price of one NP-W126S battery. (Although these 18650 cells would be typical of the cell type used in thicker bodied power banks, the ultra slim type power banks would usually use lithium-polymer "pouch cells", which are relatively flat). The NCR 18650B energy capacity (3340mAh nominal capacity x 3.6 Volts nominal voltage), is approximately 12 Watt-hours, per cell. (The new Sanyo 18650 GA cells are 3500mAh nominal capacity, so 12.6Wh of energy). In contrast, the energy capacity of the NP-W126S battery (minimum capacity of 1200mAh x 7.2V) is 8.7 Watt-hours. By converting the specifications to energy capacity in Watt-hours, it is easy to compare cells and batteries of different voltages.

A large power bank could contain perhaps eight of these 18650 cylindrical cells (or the equivalent in pouch cells). However, real electrical systems are never 100% efficient, and there are always losses, especially when voltage conversions take place. When supplying power from a USB power bank, there is an initial conversion from the 3.6 Volts of the power bank's internal cells, to the 5 Volt USB output, (and then a further conversion within the camera, from 5 Volts to the various internal voltages required by the X-T3). The 3.6 Volt to 5 Volt conversion causes a notable reduction in available energy, so, to achieve a more realistic estimate of the power advantage of the power bank supply, you can compensate the power bank's energy capacity by a percentage that allows for the 3.6V to 5V conversion losses. Since we don't know the actual loss values, you can assume 90% (or 85%) efficiency, and subtract 10% (or 15%) to allow for conversion losses. Then you can divide the remaining Watt-hours energy capacity by the 8.7 Watt-hours of the NP-W126S battery, to find the "number of batteries" equivalence of the USB power bank. So, in the case of a 20000mAh power bank (20Ah x 3.6V = 72 Wh), the finally available energy capacity (after a 10% reduction to allow for conversion losses), might be taken to be about 64.8Wh, which is about 7.4 times the NP-W126S's energy capacity.

Sealed (not designed to be opened by the user) power banks, usually don't specify what type of cells, or how many, are inside the power bank enclosure, but assuming that the stated milli-Amp-hour capacity is reliable, you can use a lithium-ion cell voltage of 3.6 Volts (or 3.7 Volts for lithium-polymer), in order to determine energy capacity in Watt-hours.

MULTI-VOLTAGE BANK VOLTAGES
Although most common power banks are designed to deliver power according to USB standards (normally 5V), it is also possible to get multi-voltage power banks. These may be of interest to the X-T3 user, since the grip can be connected to a 9 Volt power bank for charging and camera operation, and the body (without grip) can accept the DC coupler powered by a 9 Volt power bank, for operational power.

If supplying a nominal 9 Volts via the grip's DC socket, the low range tolerance is about −3%, so the voltage should not go below about 8.75 Volts; otherwise the display will flash the low power symbol (red battery with no bars), and the camera will auto power-off. However, this low range cut-off does not apply when supplying power via the CP-W126 DC coupler.

BICYCLE LIGHT BATTERY BOXES
These battery boxes are designed to power high performance lighting on push-bikes. Some of them provide both a 5 Volt USB output as well as a nominal 7.2 Volt (8.4 Volt maximum) 5.5mm male DC plug output which is suitable for connection to the X-T3 via the DC coupler (with a suitable conversion cable). Note that this voltage is not high enough for the vertical grip's DC input socket, however.

Two significant features of these battery boxes are, provision of strap lugs for secure mounting, and a high degree of weather sealing (since they are intended for mobile outdoor use).

These battery boxes usually take 18650 type cells. Ideally, each pair should be matched for internal resistance. The USB output is by a standard type-A connector.

POWER BANKS RECOMMENDED BY FUJIFILM
Fujifilm is currently recommending:

Anker PowerCore Speed 20000 PD, and
Anker PowerCore+ 26800 PD, power banks.

These have both USB-A and type-C ports. Whenever type-C PD ports are provided, they should be used in preference to the USB-A or type-C (non-PD) port, because the type-C PD port can potentially deliver more current. The PD port can deliver 5V at a maximum of 3000mA, (although the X-T3 only draws 1500mA), compared to 900mA from the USB-A port.

CAPACITY LIMITS FOR AIR TRANSPORT
For the purpose of implementing air transport safety regulations, lithium-ion (and lithium-polymer) batteries, are categorised according to their energy capacity in Watt-hours. In this context, a power bank is considered to be a "battery". The lowest and least restricted category is 100Wh or less. A power bank with over 100Wh of energy capacity would not be allowed to be carried on a passenger aircraft without the specific approval of the airline.

The energy capacity in Watt-hours can be found by multiplying the rated capacity by the nominal voltage of the internal cells. Assuming simple parallel connection, we can take 3.6V as the nominal voltage for lithium-ion cells, and 3.7V as the nominal voltage for lithium-polymer cells. If in doubt as to the type of cells, use 3.7 Volts. The 100Wh category limit explains why we see that very high capacity power banks seem to be limited to about 26800mAh (26.8Ah). The energy capacity of a 26800mAh power bank would be 26.8Ah x 3.7V = 99.2Wh, which is just inside the 100Wh limit of the least restricted category for air transport. Allowed units need to be taken as carry-on baggage, not checked-in baggage.

Section - J

DC COUPLER

The DC coupler is a common method used by camera manufacturers to provide a camera with an optional DC power socket. The DC coupler replaces the normal battery, and can provide a virtually continuous and unlimited supply of power.

ATTACHMENT
The cable exit-point is on the right-hand side of the battery chamber door. When the door is open, and the battery removed, you can use a finger-nail to pull up the rubber seal. The seal is anchored, so that it doesn't fully come away from the body.

After inserting the DC coupler, with the cable on the exit-point side, ensure that the cable feeds properly through the exit route, and close the battery chamber door. The camera can now be powered via the DC socket which terminates the DC coupler's cable. Remember to set the power Auto-Off setting to "off" to prevent the camera turning off automatically.

9 VOLT SUPPLY
The Fujifilm CP-W126 DC coupler combines with the AC-9VS power adapter to power the X-T3. A further possibility is to use the coupler to connect another appropriate (9 Volt) power source, for field usage. Because the maximum voltage of the NP-W126S battery is 8.4 Volts, an input voltage higher than 8.4 Volts, alerts the camera that power is being input via the CP-W126 DC coupler, and the "external power" symbol will be displayed instead of a battery level display. The rating for the power supply to the DC coupler is 9 Volts at 2 Amps (therefore, 18 Watt), and these specifications should guide the choice of power source. One possibility is a multi-voltage power bank which includes a 9 Volt output. The USB booster cable (described in section D), can also be used, to power the body via the CP-W126, from a 5 Volt USB power bank. However, this will only be able to deliver about 1 Amp of current, and so, would not be suitable for operation at the very highest performance levels, since there will be no internal battery to supplement the DC coupler's supply.

D-TAP
The V-Mount battery system is a portable external power system widely used in professional video and cine production. (An alternative system is the Gold-Mount system, to which the following information also applies). The system allows very high capacity battery packs to be attached to a battery plate, which can itself be mounted to a video camera rig, a tripod, or a light stand, etc. As well as standard co-axial DC power output sockets (most commonly, 12 Volt), the system also allows access to power via D-Tap plugs, that fit into sockets which can be on the battery pack, or the mounting plate.

The standard voltage of the V-Mount and D-Tap system (14.4 Volts nominal, and 16.8 Volts maximum) is too high for the X-T3's maximum of 9 Volts, however, a special voltage reduction cable can deliver the correct voltage to power the X-T3. Never connect a D-Tap output directly to the X-T3 without a suitable voltage converter.

A D-Tap to X-T3 connection will consist of three main parts: a cable with male D-Tap access plug, an in-line voltage converter to reduce from 24 Volts (maximum) down to 9 Volts, and a CP-W126 DC coupler.

These may be available as separate units, or one single cable with D-Tap, converter, and DC coupler.

The benefits of utilising the V-Mount and D-Tap system are, very high power storage capacity, the ability to power multiple devices (camera, external monitor, external HDMI recorder, video light, etc) from a single power source, built-in charge and charge monitor functions, as well as utilising the V-Mount plate and battery to counter-balance the front-heavy load of the camera in a video rig.

DC COUPLER APPLICATION
• Camera operation over long periods of time
• Static operations where the camera remains in a fixed position
• Situations where an interruption of operation must be avoided
• Situations where camera operation is be left unattended / un-monitored
• In situations where camera over-heating is an issue (for example, continuous 4K recording), removal of battery from the body can reduce number of contributors to internal camera heating

APPLICATION EXAMPLES
• Time-lapse photography extending over many hours or even days.
• Large volume copying (for example, books or documents) where the camera is mounted in a fixed copying rig.
• Surveillance photography, or wildlife photography, with automated triggering, such as a sound activated trigger, or laser trigger.

CLOCK RESET
When DC coupler is used, since there is no battery in the camera body, if DC power is turned off for an extended period of time, the camera clock will be reset. However, the camera should be able to keep its internal clock battery sufficiently charged if external power is connected at least every couple of days.

SAFETY ISSUES
Due to the camera being tethered by a power cable, various safety issues must be considered, as a matter of priority. Possible hazards include those generic to the use of AC voltages, trip hazards from cords/cables, and possible topple-and-strike hazards from cable pulling against tripods.

NOT APPLICABLE WITH GRIP
Please note that the DC coupler cannot be used in the X-T3 concurrently with the grip, because when the grip is attached, there is no exit point for the coupler's cable. However, the DC socket of the grip makes use of a DC coupler redundant anyway.

Section - K

ALTERNATIVE POWER SUPPLIES

Alternative power supplies open the opportunity to use the X-T3 remotely from mains power for extended periods of time.

AUTOMOTIVE POWER
Access to a motor vehicle allows the use of a 12 Volt to USB converter, or even the USB power socket built in to the dash of late model cars. The output should be at least 1.0 Amp, but preferably more.

Although it is common for recent vehicles to have USB outputs as standard, many of them are limited to 1 Amp of current, so you may wish to use a plug-in converter, in order to access higher current.

BUCK CONVERTERS
A buck converter is a voltage step-down device. The example shown (Deek-Robot DK-D20252 Mini DC Power Supply) provides two regulated outputs: 5V, 2A (USB), and 1-20V, 2A, from a 8-20V, 2A input.

Such a device may be useful in situations where you want to use a range of different power inputs (12V AC converter, and 12V car "lighter" outlet), or where different voltage outputs are required for a range of devices requiring different power or charging voltages. in such situations, it can reduce the number of power and charging devices that need to be carried.

Several important warnings, when using this type of buck converter: The input voltage must always be higher than the output voltage (otherwise you can burn-out the converter). Make sure that the input current is sufficient to supply the output currents. And finally, be aware that if the buck converter fails, there is the possibility of the full input voltage being delivered at the output; so make sure that the need to use the converter is weighed up against this risk.

HOW TO USE SOLAR POWER
Small portable solar panels allow the opportunistic recharging of power banks, which can then supply the camera, as well as other remote location gear. Don 't ever connect the solar panels directly to the camera. Instead, use the solar panel to charge a power bank, and then later, you can use the power bank to charge the camera batteries (internally or externally). Many portable solar power-supplies, although they deliver power via a USB socket, have an output that is unstable and subject to interruption. The voltage can exceed the allowable USB voltage by several Volts (especially if the Sunlight is very intense), if not connected to a high-enough load to bring about the appropriate voltage drop. A removable battery power bank with high capacity batteries, should place enough load on the supply, that the voltage drops to within the proper range for charging the power bank. At any rate, a catastrophic over-voltage event damaging the power bank, or its batteries, is a small cost compared to the possibility of damaging the camera. Use an inline USB power meter, so that you can be sure of what voltages are being delivered.

A folding unit, like the one shown, can give some degree of power control in ultra-bright conditions, by not being fully opened. Fully opened in decent Sun, it can easily produce 5 Watts of power. At midday in the middle of Summer, at mid latitudes, and properly aimed, it can produce several Watts more.

Since high temperatures are not good for Li-ion batteries, the power bank or charger will need to be kept in the shade while charging, if the ambient temperature is very warm. You can use a radiant barrier material (such as metalised mylar bubble sheet) to form a shade cone for this. The conical shape is used because it is easy to form, tends to be self-supporting and resists collapsing in on itself. The weight of the power bank or charger, placed within it, stops the cone from opening out.

However, in very cold climates, the battery might benefit from being warmed up by exposure to the sunlight. A battery temperature in the 20's of degrees Celsius, would be nice for the batteries.

If the Sunlight is not optimal, and if you have a removable battery power bank, rather than trying to charge the power bank, it may be more efficient to charge a single 18650 battery in a USB battery charger, and this battery can be swapped into the power bank when needed.

The solar charging system should not be set up near dried vegetation, due to fire risk. At times of extreme fire danger, it should not be left unattended at all. If you are on the move, and the Sun is at your back, you can do some charging opportunistically, by attaching the solar panels to your backpack.

Section - L

USB POWER METERS

One of the most useful devices for power management is the in-line USB power monitor. This device can display instantaneous voltage, current, and power throughput, as well as accumulated or drained milliAmp-hours, etc. Some also allow time, voltage, and current limits to be set. This device is very useful for charging situations where either the charger or the storage device (such as power bank) does not have a detailed status display. USB power meters are available with either USB type-A or USB type-C connectors.

The displayed readings will reflect some discrepancies from losses due to the power monitor's own processing and display and illumination, however the readings should be sufficiently accurate for our intended purposes.

VOLTAGE / CURRENT MONITORING
Although the camera's LED indicator shows charging in progress or charging completed, the camera needs to be switched on in order to get a more detailed indication of current SoC, and charging progress.

If a power monitor is inserted inline, it can continuously show the instantaneous supply current. The following chart gives approximate values, and does not account for conversion or other incidental losses.

When using the USB port to charge the body battery, and using an inline USB tester, the present status of the supply current is a useful indicator of the position in the charging process.

Because the actual charging current can vary according to battery condition (SoH), as well as environmental conditions such as temperature, the quoted values are mainly intended as a conceptual illustration of the significance of variations in current flow during the charge process.

Section - M

DISCLAIMER

Incorrect or inappropriate use of the X-T3's power systems, could lead to damage or even destruction of the battery, camera, or other ancillary devices. Furthermore, catastrophic failure of the lithium-ion battery could lead to serious personal injury.

Before acting upon any information in this guide, the camera user should satisfy himself / herself that they are acting with due diligence.

This guide is a compilation of information that I collected for my own use of the X-T3 camera. I am making it available in the hope that some of the sometimes difficult to obtain information, may be of use to others. However I cannot guarantee the accuracy of all of the information given here. There is the possibility that some of this information may not be correct, despite my own good intentions and diligence. You, as the camera user, must verify this information for yourself, and decide whether acting upon it, is prudent and safe. I cannot be held responsible for any damage of injury.

Directives about powering the X-T3 are given in the Owners Manual. These directives include instructions not to use non-Fujifilm batteries and non-Fujifilm chargers. Usage that fails to follow these instructions, could have the consequence of voiding your warranty.

[ Last updated: 15 November 2019 ]

THANKS FOR READING . . .

Powering the Fuji X-T3

If you would like to support me in continuing to produce high quality reference material, like this, please consider donating, maybe even the cost of a coffee.
Thanks for your support!

All images © 2018-2019 Dom Varney

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NP-W126S Counterfeits

A Visual Guide to Spotting the Fakes

The NP-W126S is the current version of the battery used by Fujifilm X interchangeable lens cameras (X-A, E, H, M, Pro, and T series). Because the NP-W126S is a premium battery which sells at a premium price, fraudsters re-badge and repackage inferior batteries, to pass them off as genuine Fujifilm batteries, in a money making scam. This guide is specifically about counterfeits, meaning that the batteries (without authorisation) carry a copy of the Fujifilm brand logo, and are designed to resemble the original product so closely as to be virtually identical to it. They are designed for the purpose of deceit.

I will present practical tests which can be used to determine whether a battery claimed to be a genuine "Fujifilm NP-W126S" is legitimate, or counterfeit. The distinctions made in this guide, reflect the situation at the time of writing. However, Fujifilm, (or the battery's manufacturer, Panasonic) could at any time, make changes to the battery, which might supersede this information: - "Specifications subject to change without notice", as they say. Because of this, it is best to frame the results of your individual tests in terms of "normal or suspect", rather than jumping immediately to a "real or fake" conclusion. Every occurrence of a "suspect" finding, contributes to the accumulating evidence that the battery may not be genuine. When the bulk of the suspicious evidence becomes compelling, then you can declare the battery a fake.

Many of the analyses shown here, can be made without the need of any instruments. If you are familiar with what to look for, you can positively identify a fake (even a very good copy), in about 2 to 3 seconds. To determine the authenticity of a particular battery claiming to be a genuine NP-W126S, look at:

[ 1 ] ORIGINAL PACKAGING

When purchased as an accessory, the original packaging of the NP-W126S battery includes the box, instructions and a plastic storage pouch for the battery.

The box and instructions are specific to the battery type (that is, they don't use a generic box and instructions sheet that suit various models of lithium-ion battery).

Some counterfeiting is very un-sophisticated: In the following phoney box, based on packaging from the past, the battery diagram shows the wrong battery (they sometimes place a barcode label over this, to obscure it).

Other discrepancies are the lack of Japanese text, and the old style Fujifilm brand with the small "Fuji" symbol, which has not been used since 2006.

That logo is an anachronism for the NP-W126S battery, which was released ten years after the change to the present Fujifilm brand logo (with the distinctive font, and the "cutting-edge" design feature on letters I and F).

[ 2 ] PRINTING ON THE BATTERY

The battery is printed on two faces, and one end (the circular orientation patch). When examining the details of the printing on the battery in question, we can look at:

TEXT & GRAPHICS LAYOUT & CONTENT
These are the current printed faces of the NP-W126S battery. As far as I can find out, there is one design for all markets. The logos of the various certifying agencies indicate a global coverage. The Fujifilm branding, battery type, and power specifications are found on the front face of the battery.

On the reverse face, can be found the contact pin-outs, safety warnings, and country of manufacture. Please note that the "JAPAN ONLY" words on the reverse side, refer to the Recycling symbol, rather than to a distribution market.

The above photographs detail the textual content of the genuine batteries. In contrast, one recent counterfeit version, mis-spells the name "Panasonic", on its front face, as "Panssonic", and on the reverse face, it gives the warning "CAUTION: Risk of Fire and Bums", instead of "Burns". Because the Fujifilm brand logo incorporates unique characteristics, such as the "cutting-edge" device on the central I and F letters, it can represent a challenge for the counterfeiter. This is the genuine form:

The counterfeiter's rendering might look OK without close inspection, but if you examine it with some magnification, you might find many anomalies:

THE INKS
The white print ink of the genuine batteries, is not an "intense" white, but could be described as a pale silvery-grey off-white. Likewise, the orange ink of the genuine batteries, tends not to be a "vibrant" orange.

In recent years, all NP-W126 class batteries have an orange coloured orientation patch on the end that faces out from the camera's battery chamber. The later series NP-W126 batteries had a square orange patch, while the NP-W126S has a circular patch.

The colour is a "burnt" orange, and is not like a "high-visibility" orange.

SCALE, BOUNDARIES & MARGINS
If you have a known genuine battery, you can compare the scale of the printed area, and the dimensions of the text and symbols boundaries. Even if precise measurements of the print boundaries cannot be done, it is often possible to visually notice discrepancies to the margins.

On the front and reverse faces, the area for printing is very slightly raised (by about the thickness of a regular sheet of paper on each face). Under good light, you can easily see the edges of this raised zone. With the genuine batteries, the upper and lower boundaries for the printing go almost to the edge of this raised surface.

On the non-genuine batteries, there may be a noticeable space between the upper and lower boundaries of the printing and the edge of the raised surface.

LAYOUT
Pay attention to the spacing between text and graphics. On one of the counterfeits, the electrical contact symbols are slightly smaller, and spaced further from the adjacent text.

Tiny layout errors can also be detected on minute examination of the text. For example, on the genuine battery's front face (with the Fujifilm logo), the tail of the Y in the word battery, lines up with the centre line of the number 6 below it:

In contrast, on one fake version, the tail of the Y lines up with just over the leading edge of the number 6:

If you have a known genuine battery to compare against, you may be able to find many printing discrepancies on the suspect battery. On this genuine battery, notice the name of the city Wuxi, is enclosed in brackets, with spaces on either side of them.

On one counterfeit battery, the spaces are missing:

SUMMARY EXAMPLE
The following gives an example of a currently available counterfeit battery. For comparison, the first photograph shows the front face of a genuine battery. The points for examination are circumscribed.

Now compare the suspect battery. Easily seen anomalies are: An inaccurate copy of Fujifilm logo (especially the "hook" of the letter J), a missing space before "NP-W126S", a dash that is too long in "NP-W126S", a stroke missing in the ム (mu) katakana script, and spaces missing either side of "(Wuxi)". There are actually many more inaccuracies, but these five are the most easily seen. Finally, of course, recall that the genuine battery is supplied with a soft storage pouch, not a hard cap.

A recent variation of this fake has "LITHIUM ION BATTERY" as a single word (with no spaces between words).

Note, also, that the "U" of FUJIFILM, is very rounded at the bottom, and of uniform thickness, in comparison to the genuine Fujifilm logo.

[ 3 ] OUTER CASE DESIGN

When a battery production facility produces tooling for the battery case, that tooling, and the production methods used, will leave characteristic signs that point to that plant or factory. No matter how good the printing is, these signs easily distinguish batteries from different manufacturers.

ANTI-REVERSAL NOTCH
On the electrical contacts end of the battery, there is a notched corner, which prevents the battery being fully inserted into the camera's battery chamber, if the battery is wrongly oriented, either end-wise or face-wise.

You can check the shape of this notch, as an indication of authenticity.

RETAINING NOTCH
This notch is for securing the battery in the BC-W126S (or BC-W126) charger, and also the battery trays of the vertical grips. The charger has a pawl which latches into this notch, so that the battery is held securely while charging.

At certain angles, the notch of the genuine battery appears to be "black". Also, check whether the corners of the notch are "square" (which they should be), or "rounded".

GATE-MARKS
Gate-marks (or, gate-scars) are remnants of the injection molding process that produced the battery's plastic case. They are tiny spots, about a millimetre in diameter.

The genuine Fujifilm battery has eight gate marks (four on one side, and four on the other side), and the positions do not vary.

Non-genuine batteries may have no visible gate-marks, or if they do have gate marks, they may be in different places, and a different number. Currently, observation of gate-marks is one of the most reliable discriminators between genuine and non-genuine batteries.

[ 4 ] ELECTRICAL CONTACTS

Under good light, the electrical contacts of the NP-W126S batteries, look quite different from those on many non-genuine batteries.

The colour should not be a "Hot" gold.

[ 5 ] SURFACE TOPOGRAPHY

On genuine NP-W126S and NP-W126 batteries, the printed faces have a slight concavity to them. They are not perfectly flat. The boundary of the face's printed area (marked in the photograph as the B zone) is raised by several hundredths of a millimetre (enough that you can feel it) above the outer edge zone (marked A). In the central area (marked C), the case is thinner than at the edges, and can be depressed by about 0.3 mm, on each face of the battery (about 0.6mm in total). If you can view the face of the battery with light just glancing across the surface, you can sometimes see these zones.

The slight concavity can easily be sensed by rubbing the battery between the fingers and thumb.

A good way to objectively detect the expected concavity, is to hold a perfectly straight edge (like a metal ruler), against the face of the battery, and viewing against a bright background, examine how the straight-edge makes contact. You should see "daylight", meaning that some light is able to pass between the straight-edge and the middle of the battery surface.

[ 6 ] MANUFACTURING CODE

On the orientation patch end of the genuine battery, there is an impressed / engraved, 8 alphanumeric character manufacturing code.

The first character indicates the year of manufacture and (for an "S" type battery) can only be:

Obviously, the I, and H are future codes, and cannot exist now (in 2019). The second and third characters are for production month and day. We don't know with certainty the meaning of the fourth and fifth characters (a hypothesis is currently being verified), but the most common combinations seem to be "1A" and "2A". The last three characters are "P", "E", and "W", standing for "Panasonic Energy, Wuxi", the manufacturer of the genuine batteries.

Check that the code conforms to the system, that the impression is fine and sharp (and not printed), that it is correctly positioned, and that it uses the correct font. Note that it is a narrow font (check the width of the "W"), and is without serifs. Check the spacing: The letters and numbers should not be "nearly touching".

Look at where the production code begins and ends, in relation to other surface landmarks. For instance, on the genuine battery, the second half of the final W, should line up with one edge of the the retaining notch.

On the following suspect battery (image from a screen capture), the E is in that position, and the W is lined up with the centre of the notch.

(Incidentally, this notch has round corners, instead of the proper "square" corners, as in the image of the genuine battery).

[ 7 ] BATTERY WEIGHT

The weight of the NP-W126S (and NP-W126) batteries, is very uniform. Rounded to the nearest gram, the battery should weigh 47 grams (or, 1.66 oz).

Weights of non-genuine batteries might range between about 39 and 50 grams (about 1.38 and 1.75 ounces). The weight difference in non-genuine batteries, is due to different construction and chemical formula, and in the case of lighter batteries, may also be due to the use of smaller internal cells (with packing used, to fill up the empty space).

[ 8 ] MATERIALS

PLASTIC TYPE
The case of the genuine battery is made of from polycarbonate. Counterfeits may use other types of injection molding plastics. When photographed in Infra-Red (IR) light, different plastic types may show different levels of absorption and reflection, despite being the same shade in visible light. Gate marks also show up more clearly under the IR illumination.

In the above photograph, the upper and lower batteries of the stack were genuine Fujifilm batteries, while the middle battery was non-genuine. Under IR light, the non-genuine battery's different type of plastic appeared much lighter. The IR photograph (converted to monochrome) was taken using an un-modified X-T3 camera, with Infra-Red only illumination (no visible light), but no special lens filter.

[ 9 ] THERMISTOR

The thermistor allows the battery's charging and discharging temperatures to be monitored. In general, only the genuine OEM batteries have a functioning thermistor. If you have a digital multi-meter (DMM), you can easily check if the battery has a functioning thermistor. Measure the resistance between the [T] contact and the negative contact of the battery.

Take note of that resistance in kΩ (kilo-Ohms). At comfortable room temperatures it might typically be between 7 to 20kΩ.

Now slightly warm the battery by placing it under the armpit or between the two palms of the hands, for several minutes. Finally, measure the resistance again. There should have been a significant drop in resistance, of at least several kΩ. This temperature dependent variation in resistance indicates a functioning thermistor. If there is no functional thermistor, then the thermistor circuit will have been replaced by a fixed-value 10kΩ resistor, connected between the [T] contact and ground, on the battery's internal power board. The non-genuine battery manufacturer has to do this, because the BC-W126S battery charger won't initiate charging unless it sees an acceptable resistance at the [T] contact. In this (non-genuine) case, the resistance will remain at 10kΩ, continuously indicating to the charger that the battery is at a "safe" 25° Celsius (77° Fahrenheit), regardless of the battery's true temperature.

[ 10 ] TYPE "S" INDICATION

A genuine NP-W126S battery will register as such when inserted into an X-H1 or X-T3 camera (it will have a white battery symbol, rather than the "non-S" type battery's yellow symbol), however, earlier cameras such as the X-T2, will not display such a distinction.

Note that it is possible for a fake NP-W126S battery to trick an X-H1 or X-T3 camera into identifying it as an "S" type, and showing with a white display. This is because the camera distinguishes between "S" and "non-S" type batteries by interrogating the resistance on the [S] contact of the battery, and this value can easily be manipulated by an un-authorised battery manufacturer. You can verify this by placing a small piece of tape over the [S] contact of a non-S (genuine or third-party) battery, and loading it into an X-H1 or X-T3 camera: the battery will now register as an NP-W126S battery. Importantly, however, a genuine NP-W126S, will always show a white battery display, so showing yellow would indicate that it is not a genuine "S" type.

Even if you don't have an X-H1 or an X-T3, you can still test whether the battery gives an "S" type indication, by using a DMM. This is tested by checking the resistance between the [S] contact and the negative contact of the battery.

The genuine "S" type battery will show a resistance of about 680kΩ.

[ 11 ] DISCHARGE CHARACTERISTICS

Because of their different chemistry, the non-Fujifilm batteries have different discharge characteristics. This causes the battery level display (which is calibrated for the genuine battery), to behave abnormally, during heavy usage.

[ 12 ] IN-SERVICE SIGNS

It is generally not possible for the user to open and chemically analyse a lithium-ion battery. However, the different chemistry and support electronics of the non-genuine battery, can be inferred by operational discrepancies. If a counterfeit is put into service, we may experience some of the following issues:

[ 13 ] SELLER 'S ONLINE DESCRIPTIONS

A case study: This is from an offer by an eBay seller in the United States. Screen captures have been redacted, so that the seller is not identified. The first suspicious feature of this offer, is a price well below the genuine battery's typical market price, without any reasonable explanation for the low price.

Next, although the "Fujifilm" brand-name appears prominently in the title, it actually points to the applicable cameras, rather than the battery. So, instead of saying the battery is a "Fujifilm NP-W126S Battery for X-T2 (etc.)", it says an "NP-W126S Battery For Fujifilm X-T2 (etc.)". And, if you read the "Item Specifics" section, the Brand is specified as "Unbranded", despite the accompanying photograph showing a "Fujifilm" branded battery.

Significantly, the product description includes this message: "Note that this battery is not compatible with the XH-1 Camera", (an absurd statement, since the NP-W126S battery is the prescribed battery for the X-H1). The reason for making this statement is because this fake battery would give a yellow battery-level display in the X-H1, alerting the user that the battery is not a true NP-W126S at all. Finally, throughout the description, the seller never actually refers to the battery as "genuine". Based on these facts, it would appear that the seller is aware that the battery is a fake, but is attempting to sell on the basis of Caveat Emptor ("Let the buyer beware"). However, if the battery is a counterfeit (the pictured battery is virtually identical to an original Fujifilm battery, and bears the Fujifilm corporate brand logo), and if the seller knows that it is counterfeit, then it is a case of trafficking in counterfeits, which is illegal under US federal laws, as well as many other national jurisdictions.

[ 14 ] REPORTING COUNTERFEITS

Re-badging non-genuine batteries as "genuine", and attempting to deliberately deceive buyers in order to secure unlawful gain, is a type of fraud, and as such, has serious legal consequences.

Typically, we don't know who the original perpetrator of the fraud is. But we almost always know who the retail seller is, so you should seek redress from the seller. (The seller may not be aware that the batteries are counterfeit, although they really should suspect such, based on their lines of wholesale supply). Request that a full refund be issued, and that any other similar batteries to be withdrawn from the market.

If the seller refuses your request, and if the fake battery was bought on-line, you should escalate to reporting the fraud to the online marketplace that you used. Depending on whether the seller is within, or outside of, your own country, some of the following organisations may be interested in being alerted to vendors who are selling counterfeits:

Fraudsters depend on the potential buyer's lack of familiarity with the genuine product, to be able to accomplish their deception. By educating yourself and others, you not only protect yourself from monetary loss, and possible damage to your person or camera, but you also decrease the attractiveness of the battery supply market as a place for fraudulent enterprise.

[ Last up-dated: 25 June 2019 ]

THANKS FOR READING !

NP-W126S Counterfeits

If you would like to support me in continuing to produce high quality reference material, like this, please consider donating, maybe even the cost of a coffee.
I really appreciate it.

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The Great Battery Brawl

Fuji versus 3rd Party NP-W126/S

in a 12 Round Contest

" I need a new battery for my Fujifilm X-series camera. Should I buy the genuine Fujifilm OEM (Original Equipment Manufacturer) battery, or should I buy an alternative 3rd Party battery?"

With this question, you have just re-ignited a conflagration, a battle of opinions that has been raging for years. Those backing the 3rd Party Contenders, claim that you are just wasting money by buying the Fujifilm OEM battery, because the best 3rd Party batteries can deliver similar performance at a much lower price. The response from the OEM Champ's backers, is that any monetary savings represent false economy when the other "costs" of using a 3rd Party battery are taken into account (for example, they claim that safety is compromised). Well, it's time to finally settle this dispute. So now, get ready for the ultimate decider. But don't expect a knock-out; this will probably go down to a points decision. Be prepared to exercise minute attention to technicalities, because in this ring, YOU will be the referee, and the ultimate adjudicator. The contest will go a distance of 12 rounds:

1 - Price
2 - Capacity
3 - Discharge characteristics
4 - Temperature management
5 - Battery swelling
6 - Power capability
7 - Self discharge
8 - Battery ageing
9 - Control codes
10 - Warranty
11 - Reliability
12 - Ultimate value

" OK, Batteries. I expect a good, clean fight.
Protect yourself at all times.
Now, return to your corners and come out at the bell. "

[ 1 ] PRICE

Price is, of course, the pivotal issue of the contest, and we could even say, the " sine qua non" issue of the fight, since if there was no price difference between OEM and 3rd Party batteries, most people would just buy OEM.

PRICE DIFFERENCES
There can be very significant price difference between the Fujifilm OEM battery and even the most costly of the 3rd Party batteries. So it is understandable that people might consider the use of alternative batteries to the OEM battery.

In the above table (based mainly on the US market), the OEM battery has been assigned a value of 100 price units, simply to make relative costs more apparent, since they can be treated as percentages. For each of the batteries listed, the current $US price is about two-thirds of the "price units" value given (except for Patona brand which is not distributed in the US, and so, does not have a regular US "street" price).

COST VERSUS SERVICE LIFE
The OEM battery supporters claim that the 3rd Party batteries don't last as long as the OEM battery. But even if this is true, the shorter life is offset, to some extent, by the lower cost. To explore this, let's assume that the OEM battery can provide a service life of 4 years, or 48 months (which, based on experience, is a realistic assumption). Now compare it to a hypothetical 3rd Party battery, costing 35% of the OEM battery's cost (that would put it in the upper price group of 3rd Party batteries). This hypothetical battery's service life would have to be reduced down to about 18 months, before it started to become un-competitive with the OEM battery, on the basis of cost. If the hypothetical battery's service life turned out to be longer (which is likely for its price category), then the cost advantage over the OEM becomes even more compelling.

Of course, a shorter service life means that you have to purchase more batteries in order to match the OEM's 48 months of service. This repeating battery purchase produces other effects.

BUDGETARY ADVANTAGE
Assume a hypothetical 3rd Party battery, which only costs one third of the OEM cost, but only lasts one third of the OEM life. You would have to buy a second one, and then a third one, later, to match the life of the OEM battery. In the long run, the users of the 3rd Party battery, and the users of the OEM battery, both spend the same total amount of money over the same period of time. However, the lower cost battery effectively allows the user to spread the battery costs, and pay one-third now, one-third later, and another third later still. The user may appreciate this as a significant budgetary advantage.

MORE FREQUENT BATTERY FADE PERIODS
On the other hand, frequent battery renewal, comes with a more frequent experience of transitional service, due to battery fade. In the transition period (when the battery is coming to the end of its life), the battery goes from performing acceptably, to performing unacceptably. This period can be marked by annoying, unreliable, and uncertain battery behaviour; shots per charge drops rapidly, and the possibility of unanticipated "low battery" shutdowns is increased. You might prefer not to go through this transition period any more often than is necessary. However, if the 3rd Party battery can match the service life of the OEM battery, this argument has no merit.

PRODUCTION OF WASTE
Some people say "Buy cheap batteries, and just replace them frequently". However, if we again take the case of the hypothetical "one-third-price, one-third-life" battery, it could be argued that this battery produces three times as much waste (and three times the carbon footprint of production), because you have to buy three of them, rather than a single OEM one. In the long-term, the longest life battery (which may be the OEM battery), produces the least waste. This is an issue rarely raised, in the debate, but perhaps it should be, given our rising consciousness of environmental issues.

DELIBERATION
For the price issue, there are are reasonable arguments from both sides of the debate. But, although price differences are clear and substantial, there is a saying that "money is not everything", and a decision based on this criterion alone, may be superficial. The implications of battery choice are multivariate, and there are other significant issues that we need to consider. We will revisit the price issue when we eventually look at ultimate value.

[ 2 ] CAPACITY

Many 3rd Party batteries seem like a great "buy" because, not only are they cheaper than the OEM battery, but they also boast a higher capacity. Unfortunately, battery capacity is a complex topic, which is often poorly understood. It is worthwhile exploring this area in some depth. Let's try to make sense of the numbers.

The NP-W126S battery is a nominal 1260mAh (milli-Amp-hour) battery. The 1260mAh capacity is indicated by the "126" in the battery's name, which is the capacity, with the final zero dropped. In the same way, the GFX camera's NP-T125 battery is a 1250mAh battery (with the final zero dropped to give the name). This is Fujifilm's current battery naming practice for these and any new twin cell (NP-Wxxx, W indicating tWo or tWin), or triple cell (NP-Txxx, T indicating Three or Triple) batteries. (Note that the naming system used for the older single cell batteries is different).

The genuine OEM NP-W126/S battery was designed around the Panasonic NCA673440 prismatic lithium-ion cell. ("Prismatic" differentiates the shape from cylindrical and pouch type cells).

There are two of these cells in each battery. For reference, this cell has a volumetric energy density of 0.47 Watt-hours per cm³, and a gravimetric energy density of 0.213 Watt-hours per gram.

Recognition of the dual cell nature of this battery will be important for understanding some of the "capacity" concepts, and will help avoid some specification misunderstandings.

ELECTRICAL SPECIFICATIONS
The Fujifilm NP-W126S battery has 5 electrical specifications printed of its front face:

Because the battery's terminal voltage continually reduces during discharge (going from 8.4V down to 6.0V), the battery is assigned a "nominal" voltage, which is the half-way point between maximum voltage (8.4V) and minimum discharge voltage (6.0V).

3rd Party batteries typically state only the nominal voltage, nominal capacity, and the nominal energy of the battery.

Although photographers may pay little attention to the nominal energy specification, it is required to be stated on the battery for the purpose of determining compliance with air-transport regulations, because it is a better indicator of the amount of energy that could be released in an explosive or rapid combustion event. Using the nominal energy specification, batteries are differentiated into one of three categories (less than 100Wh, up to 160Wh, and over 160Wh), in order to determine which air transport rules apply to them (for instance, how many spares a passenger is allowed to carry). Stills camera batteries are all in the lowest (< 100Wh) category. For reference, one Watt specifies a power of one Joule per second, and one Joule is equivalent to one Newton-metre.

COULOMETRIC CAPACITY
This is the specification most people think of when considering capacity. The nominal, or coulometric, capacity, specifies a current (a flow of electrical charge) which can be sustained for a one hour period of time, and is expressed in milli-Amp-hours (mAh). The NP-W126S's 1260mAh nominal capacity can, in theory, continuously supply 1260 milli-Amps of current for 1 hour, or the various mathematical equivalents, such as, 630mA for 2 hours, or 2520mA for half an hour, etc. In practical terms, the nominal or coulometric capacity is an indicator of how much use we can expect to get from the battery before it requires recharging. In photographic terms, it will be a major factor in determining how many shots we get per battery charge. Coulometric capacity is closely related to the battery's internal cell size (and the volume of active material contained within the cell), but it is not directly related to total battery size, since it does not take into account the number of internal cells which comprise the battery.

ENERGY CAPACITY
The other measure of battery capacity is the battery's energy capacity, or nominal energy, expressed in Watt-hours (Wh). The nominal energy can be found by multiplying the capacity by the nominal voltage. So, for the NP-W126S battery, the nominal energy would be: (1.20Ah x 7.2V) = 8.7Wh. (Note that Fuji uses the minimum capacity, 1200mAh, rather than the typical capacity, for this calculation). The nominal energy is often overlooked, however it does put battery capacity into a different perspective, and also resolves the "typical capacity" anomaly that can be noticed when, for instance, comparing the three different sized batteries in the following table.

It might seem counter-intuitive that the biggest battery (the NP-T125), has the smallest "typical" capacity, while the smallest battery (the NP-95) has a significantly higher capacity. To simplify the explanation of the difference between the two types of capacity specification (energy and coulometric): one specification answers the question "How much?" (energy), while the other answers the question "For how long?" (running time). The battery's nominal energy, expressed by its Watt-hour (Wh) rating, takes into account the voltage of the battery, and that normalises the relationship between size and "capacity". The voltage will depend on the number of cells in the battery pack, which ranges from single to triple, for still camera batteries. The cells are connected in such a way that their individual voltages (3.6V) add together, but the total mAh capacity does not change from that of a single cell. All NP-W126 type batteries, will be twin cell, and have a reference voltage of 7.2 (or 7.4) Volts. Because the nominal voltage is a mid-point voltage, between maximum voltage and lowest allowable discharge voltage, if the manufacturer uses different end-points (specifically, a different minimum discharge voltage), then the mid-point voltage can vary. This explains why some 3rd Party batteries state their nominal voltage as 7.4 Volts. However, the 7.2 Volts and 7.4 Volts are only "indicative" voltages, and they effectively point to the same characteristic voltage.

DIFFERENCES IN MARKET CAPACITIES
The reason the Fujifilm NP-W126S battery has a nominal capacity of 1260mAh is, because that's about the capacity limit for a battery of that size within the constraints of the current lithium-ion technology. Since the OEM and 3rd Party batteries are all the same size (they have to be, in order to properly fit the camera's battery chamber), why do the various 3rd Party battery manufacturers specify different capacities? A survey of 3rd Party NP-W126 batteries on the market currently, has batteries ranging from 1600mAh down to 950mAh. (I did not include the claimed "1900mAh" batteries, on the basis of their lacking credibility).

There are several explanations for this wide discrepancy in quoted capacities for batteries of the same physical size:

CAPACITY TESTING CONDITIONS
In testing, the capacity may have been determined at a different discharge rate (C-rate) than the OEM battery. Since capacity varies with C-rate (an effect called capacity offset), this can lead to differences in the reported capacities. If the discharge testing is performed at a low discharge current, the measured capacity will be higher, and if performed at a high discharge current, the measured capacity will be lower. When increasing the C-rate from 0.2C to 1.0C, the capacity reading is decreased by about 10%. Capacity testing at different ambient temperatures will also cause variation in the reported capacities. For instance, a battery that recorded 1220mAh of capacity when tested at 25°C (77°F), might only record 1200mAh when tested at 20°C (68°F).

The Fujifilm battery specification is based on a discharge rate of 1.0C, at 25°C / 77°F. Full specification data sheets for lithium-ion cells (like the NCA673440) will specify the C-rate and ambient temperature at which the capacity was determined. However, similar information for the internal cells of 3rd Party batteries is, in practical terms, "un-discoverable" for most battery users.

TYPE OF SPECIFICATION
The manufacturer can have quoted either the maximum capacity, the typical (or average) capacity, or the minimum (or rated) capacity. The capacity could also be an indicative capacity based on theoretical calculations (for example, cell weight multiplied by the typical gravimetric energy density ), rather than practical measurements. Most frequently, it it not stated which of these specifications is being used.

OPTIMISATION
The specific design of a battery's electrochemistry either optimises it for Power, or optimises it for Capacity, but the battery can't be optimised for both. The power oriented battery is able to answer demands for continuous high current (such as might be needed for shooting 4k video). In contrast, the capacity oriented battery, is able to supply low power photographic use (single-shot stills shooting, at a low rate), for a large number of shots.

Because of this difference between power optimised and capacity optimised batteries, it is possible for a 3rd Party battery to get more shots per charge than the OEM battery, but then perform poorly when supplying power for high definition video, or high frame rate, continuous shooting.

LOWER CAPACITY CELLS
A lower quoted capacity may indicate smaller internal cells, so there is less active material (the substances responsible for the electrochemical activity which produces the electricity). That reduction in the amount of active material would show up as a measurable reduction in battery weight. Note that even a slight decrease in the cell's linear dimensions, can produce a significant decrease in volume, weight, and nominal capacity. For instance, compare the NCA673440 with the FT603040 lithium-ion cell, which appears to be about the same size:

(The chart also shows that the string of numbers in each cell name, actually indicates the approximate cell dimensions). The OEM battery weighs 47 grams or 1.66 oz (20.3g for each cell, and about 6.4g for the circuit board and case). The lower capacity battery's weight may go down to around 40 grams or 1.4 oz (with about 15g per cell, plus a few grams of packing material, to hold the slightly smaller cells in position).

Lower stated capacities are probably reliable, since there is little market advantage to be gained by quoting a lower capacity than the competitors. One important point regarding lower capacity batteries, is that they are more likely to overheat while charging, leading to swelling. This is because the charger is typically designed to charge a 1200mAh battery, so the charging current might be higher than is optimal for the lower capacity battery.

CONFUSED SPECIFICATIONS
A 3rd Party battery producer (the battery assembler, rather than cell manufacturer), may be confused about the conventional way of determining or stating a battery's electrical specifications. The problem is typically due to a confusion between cell specifications, and battery specifications (A battery is a cluster of cells, in the case of the NP-W126 battery, two cells). Specifically, there can be confusion over whether or not a particular specification should be doubled, due to the use of two cells in the battery.

In the first example (shown above), the stated voltage of 3.7V, is the cell voltage, where they should have stated the battery voltage of 7.4 Volts (2 x 3.7V). As a consequence, the nominal energy specification of 3.5Wh is also wrong; It should have been 7Wh. In the next example, the nominal capacity is stated as 1360mAh.

Upon opening the battery, the internal cells were found to be 680mAh capacity (from the cell manufacturers specification sheets). The battery capacity should have been stated as 680mAh, and should not have been doubled to give 1360mAh. My experience is that this error is quite frequent. Be wary of any NP-W126 type battery stating a capacity higher than 1300mAh. You will often find that they are actually half the stated capacity. However, they can still work well, even if giving less shots per charge than the OEM battery.

EXAGGERATED SPECIFICATIONS
The final reason for a wide variation in capacities is that the battery may have its specifications mis-represented, or exaggerated. At least one battery on the market boasts 1900mAh capacity, but actually delivers less than 700mAh.

Erroneous "doubling" of 700mAh would only have given about 1400mAh (still on the high side). If the discrepancy between claimed and actual capacity is significant, and intentional (with the goal of deceiving), then the battery is a fraudulent battery. There is no need to consider these un-trustworthy batteries any further.

TRADE-OFFS
If the battery is specified as a higher capacity than the OEM battery, you should reflect upon why this could be the case, and take that into your considerations. Don't expect to get higher capacity than the OEM battery, without some other trade-offs, which could be in terms of, poorer performance under heavy loads, increased self-discharge rates, decreased battery life, etc.

DELIBERATION
Due to the reasons given above, it it typically not very productive to compare batteries on the basis of their self-quoted capacities. Also, to get battery performance that is similar to the Fujifilm OEM battery, the 3rd party manufacturer should strive to use battery chemistry close to that of the OEM battery, and so we would expect a similar (not higher) mAh capacity. Highly respected 3rd Party batteries like Watson and Patona, quote capacities that are very similar to the OEM battery's capacity. My own experience, and that of many others, is that the best 3rd Party batteries can deliver a capacity similar to the OEM batteries. However, even with a genuinely equivalent capacity to the OEM battery, there may still be differences in power delivery rate, self-discharge rate, and ultimate rate of decline in battery's SoH (State of Health). So, although capacity need not be a deal breaker issue for the OEM vs 3rd Party decision, it is not the only performance specification that needs to be considered.

[ 3 ] DISCHARGE CHARACTERISTICS

Discharge characteristics can be an issue, because they affect the feedback that the camera gives to the user, regarding the battery's State of Charge (the remaining charge of the battery). This is what is indicated by the battery level display when we are using the camera. The battery level indicators of the Fujifilm X-series cameras, are calibrated for the Fujifilm OEM batteries. Because other batteries differ in their chemistry, they produce different discharge curves (voltage plotted against capacity).

Not only are discharge plots non-linear, but those typical of 3rd Party batteries also have a different shape and more prominent inflection points, in comparison to the OEM batteries. Because of this, the battery level indicator produces some anomalies when using these 3rd Party batteries.

A typical experience when using 3rd Party batteries under high power discharge situations (4k video, or high frame-rate continuous shooting), is that the charge-remaining indication is exaggerated (the actual capacity is less than what is shown), and there is little or no warning given of immanent shut-down due to battery depletion. Frequently, the indicator goes from two bars directly to empty.

For some photographers, this is both annoying, and disruptive of workflow, due to insufficient warning of power shut-downs. Other photographers just adapt, and prepare for a battery change whenever the "two bars" indication is reached. Besides, if you are not putting extreme demands on the camera, the effect is much less noticeable.

OLDER CAMERAS
If you are using an older X-series camera (pre X-T2), any display differences due to different discharge characteristics, may be a minor issue.

The older battery level display lacked resolution, and may not differentiate OEM from 3rd Party batteries in any meaningful way.

DELIBERATION
This issue does not actually affect the battery's functionality in terms of capacity, shots per charge, or life expectancy. It might be considered as an issue affecting the quality of the user experience, and its significance, will very much depend on your personal tolerance for such technical anomalies.

[ 4 ] TEMPERATURE MANAGEMENT

Temperature management is a critical issue for lithium-ion battery safety and service condition. Although reported cases of catastrophic failure are fewer than with, as an example, notebook computer batteries, incidents with camera lithium-ion batteries do occur. Reported cases of camera battery related venting and combustion events include: A camera battery catching fire on an aircraft departing Chicago O'Hare Airport in 2013, a smoking camera battery at Raleigh Durham Airport (North Carolina) in 2017, an exploding camera battery at Orlando International Airport in 2017, and a camera battery catching fire (while charging) in Norway during 2018. Probably, most incidents occurring in a domestic context are not reported.

Extreme temperature conditions can both damage the battery, and/or render it unsafe. When being charged, lithium-ion batteries must not go outside of the temperature range 0°C to 45°C (32°F to 113°F). At temperatures below 0°C / 32°F, metallic lithium becomes permanently plated on the cell's anode (effectively producing a loss of available lithium salts for the electro-chemical process), and ion diffusion rates on the anode are reduced. At temperatures above the upper allowable range, there is cumulative and permanent loss of capacity and reduction in charge acceptance.

If a lithium-ion battery reaches about 150°C (about 300°F), it may vent (the cell's pressure relief valve opens, or its "burst plate" ruptures, to relieve pressure).

During venting, not only are highly flammable gases released, but electrolyte can also be released as liquid, droplets, or vapor. If venting occurs while inside the battery chamber, the battery can leak hot electrolyte fluid (containing solvents) from its terminal openings, into the battery chamber. Electrolyte leakage will be noticed as a black residue in the terminal area. In the worst case scenario, if the battery is able to reach a temperature of over 200°C (390°F), second venting and thermal runaway can occur. Thermal runaway will be the prelude to a violent incendiary event.

Because of the hazards posed by lithium-ion batteries, if operated outside of their "safety envelope", all lithium-ion camera batteries include a circuit board for battery management and protection. Ideally, the circuitry should maintain balanced cell capacities, and guard against deep discharge, overcharging, short-circuit or over-current, and temperature range violation. The following image shows a circuit diagram representing is a protection circuit arrangement.

At a minimum, the circuit board typically uses a purpose-designed lithium-ion controller IC, combined with a MOSFET (metal oxide semiconductor field effect transistor) device for on/off switching of current.

Below is shown the actual protective circuit board (which also serves as the terminal board), of an Fujifilm NP-W126 battery.

Besides the positive and negative battery terminals, the protection board for the NP-W126/S or equivalent batteries, also has circuitry connecting to [S] and [T] terminals, so that there are four battery terminals.

The [T] terminal (standing for either Temperature or Thermistor), is (or should be) integral to the thermal protection of the battery while charging.

OEM USES THERMISTOR
The Fujifilm OEM battery uses a thermistor (implemented as a tiny surface mount device on the battery's protection circuit board), for temperature management. A thermistor is resistor whose resistance output is highly temperature dependent.

In its NTC (negative temperature coefficient) form, the resistance is inversely related to the thermistor's temperature. NTC thermistors exhibits a large, precise and predictable decrease in resistance as their core temperature increases.

Other reasons for using the thermistor are, good tolerance to shock and vibration, and little need of output signal conditioning (just a single capacitor for ripple suppression). The small size of the NP-W126/S thermistor (less than 1mm long), gives a low thermal mass, resulting in minimal lag for measurement of rapidly changing temperatures. The thermistor outputs a 10kΩ (kilo, or thousand, Ohm) resistance at a temperature of approximately 25°C (77°F). A reduced resistance indicates an elevated temperature, and vice-versa. The [T] terminal of the BC-W126S charger (or the camera, if utilising in-camera charging) reads the resistance on the battery's [T] terminal, and is able to determine the battery's internal temperature, and decide whether it conforms to the safe-charging temperature limits. Charging is terminated if the battery temperature goes outside the safe range.

NO THERMISTOR IN 3rd PARTY BATTERIES
Although it would seem reasonable to assume that 3rd Party batteries would implement this same thermistor driven system of charge-temperature management, it is generally not the case. 3rd Party batteries generally do not employ a thermistor. However, simply omitting the thermistor is not really an option, because the Fujifilm chargers (and cameras capable of in-camera charging), will not allow charging to initiate, unless a resistance indicating a temperature within the safe operating range, is found on the battery's [T] terminal. (You can verify this by placing a small piece of tape over just the [T] terminal of any "NP-W126" battery, and trying to charge it in a Fujifilm charger, or by using in-camera charging; charging will be blocked). In order to fulfill this "valid resistance" requirement, the 3rd Party batteries typically use a simple fixed-value, 10kΩ resistor in place of the thermistor circuit. The fact of the 10KΩ resistor substitution, is verified, not only by measuring resistance at the [T] terminal over a wide range of temperatures, but also by "cracking-open" various 3rd Party batteries, and examining the circuit boards. Note that the charger (or camera) is unable to tell whether the resistance being read is output from a thermistor or fixed value resistor. If you have an understanding of printed circuit boards and know what a "via" (vertical interconnect access) is, you will be able to trace the 3rd Party battery "T" circuit on the following image.

The result of using the 10kΩ fixed-value resistor, is a battery which tells the charger or camera, that the internal battery temperature is a very acceptable 25°C (77°F), regardless of the actual battery temperature, and even if the actual temperature is outside the safe range. Although precision grade (limited variation from the nominal specification) and aged (which reduces the tendency to "drift") thermistors can be costly, it is probable that using a resistor rather than a thermistor, also has some fabrication and assembly advantages for the 3rd Party battery maker, besides cutting component costs.

CONSEQUENCES OF NO-THERMISTOR
Likely consequences of not implementing the thermistor circuit are that, each time the charging process transgresses the allowed temperature range, the battery sustains some cumulative and non-reversible damage. Its performance might decline (and a corollary of this would be a reduction in service life), and the battery may eventually begin to swell, due to internal pressure caused by the over-heating, with the possibility of becoming stuck in the camera's battery chamber. Less-likely (based on the relative infrequency of reports) but more extreme consequences are the battery catching fire or exploding.

TEMPERATURE MANAGEMENT AS A SYSTEM
Does that mean that by using an OEM battery, my charge process is always temperature protected? Actually, "No". Importantly, thermistor temperature management is a system , which not only requires the battery's ability to send its temperature information, but also the charger's (or camera's) ability to read and interpret that temperature information.

So, if you have a Fujifilm OEM battery (with thermistor), but you are using a 3rd Party charger with no [T] terminal, the thermistor data is virtually useless, because the charger has no way of reading it. If you are using a USB charger (which Fujifilm does not offer), you may notice it has no [T] terminal, and therefore there will be no temperature management advantage by OEM batteries over 3rd Party batteries, despite having a thermistor.

An exception to this, is the Nitecore FX1 dual (the second battery bay is on the underside) USB charger, which does have a [T] terminal, to monitor the thermistor readings. However , protection, in this case, is not automatic. The FX1 charger will report the correct temperature of a thermistor equipped battery, but it does not terminate charging if the battery goes outside the 0°C to 45°C allowable charging temperature range. The user needs to stop the charging process if they notice that the temperature display is approaching the 45°C charge temperature limit. [Thank you to Michael Kluth, who provided further valuable information regarding the FX1 charger 's operation].

However, in-camera or in-grip charging, always accesses the [T] terminal, which is why older Fujifilm cameras like the X-T1, which only had two battery terminals in the battery chamber, could not have implemented in-camera charging.

If you are using a two terminal ( [+] and [−] only ) charger, then the having or not having a thermistor by the battery, becomes an irrelevant factor. On the other hand, the JJC DCH-NPW126 USB dual charger has a temperature sensor built into the body of the charger, and this should extend over-temperature (but probably not under-temperature) charge protection to all batteries, whether they have a thermistor or not.

The Watson Duo Charger also states in the Owner's Manual (page 5), that it provides overheat protection: "The Duo Charger senses when the battery is about to overheat and immediately stops charging".

Once again, the heat sensor must be built into the charger, because the battery mounting plates do not have contacts to read a thermistor built into the battery. (There may be other chargers with built in temperature sensor, but I am unaware of any verified alternatives, at the moment).

The charge temperature management that you get (or don't get), depends on your combination of battery and charger setup. By selecting an appropriate battery-and-charger combination, you can ensure protection from over-heating, even when using 3rd Party (no thermistor) batteries.

COLD CLIMATES
If you are living in a very cold climate, and you are not using high C-rate charging, battery over-heating while charging may not be an issue. It is normal for the battery's temperature to rise by about 5° of the Celsius scale, or 9° of the Fahrenheit scale, during moderate C-rate charging. In very cold conditions, the battery's temperature might be able to rise by several times that amount, without getting close to the upper limit for charge-temperature. In cold climates, your main problem may be to ensure that you do not attempt to charge the lithium-ion battery at freezing or sub-freezing temperatures (which will severely damage the battery, due to lithium plating).

HIGH CHARGE RATES
Batteries become hotter when charged using high currents, so charge rate is relevant to temperature management. C-rate specifies the limiting current during charging or discharging of a battery. The C-rate is the ratio between capacity (in milli-Amp-hours) and current (in milli-Amps), normalised against a time period of one hour. So if we use a 1200mA current to charge a 1200mAh battery, (a ratio of one to one), the charge time would be (in theory), one hour, and the C-rate would be 1C. If we used 600mA of current to charge the same 1200mAh battery, the time taken would be two hours, and the C-rate (only half the charging efficiency of the first case), would be 0.5C. Please note that, during the second half of the charge process (the saturation phase), the current rapidly drops below the value represented by the nominal C-rate, so you cannot accurately calculate charging times, based solely on the C-rate.

For a 1200mAh battery, 0.7C or higher is considered a "high" C-rate, which would indicate a charge current of about 840mA, or higher. It is generally not advised to charge batteries of the NP-W126/S type, at C-rates higher than 0.7C (although the Fujifilm BC-W126S charger can output 0.75C, compared to the 0.6C of the previous BC-W126 charger). Most of the regular (not-fast) chargers use a C-rate of about 0.5C (so, current value is half the capacity value), which gives a charge current of about 600mA. In comparison, the Nitecore FX1 charger is rated at a maximum output current of 1000mA, and so it would be considered a "fast" charger.

This high charge rate is possible because because the user can monitor the temperature on batteries that have a thermistor. (But what if the battery doesn't have a thermistor, and so tells the charger that it is 25°C, regardless of its actual temperature?)

DELIBERATION
On the issue of charge temperature management, the battery cannot be considered in isolation from its intended method of charging. If you are considering a setup that does not implement charge-temperature management, you should satisfy yourself that the risk of battery swelling, or even of a catastrophic-failure type charging event is minimised and acceptably small.

[ 5 ] BATTERY SWELLING

Battery swelling is a common phenomenon with some 3rd Party batteries. However, it is virtually unknown with properly charged and used Fujifilm OEM batteries. The several cases I know of, where the "Fujifilm" battery was reported to have swollen, each turned out to be a counterfeit battery.

CAUSES OF SWELLING
Swelling, where the central thickness of the battery noticeably (and permanently) increases, indicates that the battery has been overheated, usually during charging. Overheating produces gasses, mainly hydrogen and carbon-dioxide, as well as carbon monoxide and ethylene (C2H2) from reduction of the ethylene-carbonate electrolyte. This evolution of gases increases the internal pressure of the two prismatic cells, and causes deformation tending towards a spherical form, because the round shape distributes the pressure induced stresses more uniformly. Because there are two prismatic cells, there are four significant deformation surfaces. Upon cooling however, the external to internal pressure gradient is insufficient to return the cells to their original flat shapes.

TOLERANCES
The NP-W126/S battery fits the X-cameras by fairly narrow tolerances (less than 5%). On the X-T3, the battery's fit to the battery chamber allows about 0.5mm (20 thousandths of an inch) of "play" in the dimension sensitive to swelling, to allow for easy insertion. That play is equivalent to about 3% of the battery's nominal thickness.

In comparison, a heavily swollen un-branded battery that was assessed, exceeded the chamber width measurement by 0.4mm (16 thousandths of an inch), giving about 6% increase to the central thickness.

There is enough structural "give" in the battery chamber that, by pushing firmly, you would be able to fully seat the swollen battery, (which would "wedge" its way in, because the battery's ends are typically not swollen, only the centre). However, the battery will not easily release, and you may have to resort to heavily striking the camera against your hand ("inertia" release), a damaging use of tools ("extraction" release), gluing a tab to the end of the battery ("adhesive" release) or even having to partially dismantle the camera, to get the battery out.

EFFECTS OF SWELLING
A swollen battery poses the following problems. If inserted into the camera's battery chamber, it may become difficult to remove, and there is the risk of damaging the battery chamber in attempting to remove the battery. If the battery swells significantly while inside the battery chamber (this could happen if you are utilising in-camera charging of a "resistor instead of thermistor" type battery), the battery could stress, bend, or crack, the chassis and circuit boards that either form or adjoin the walls of the battery chamber. However, even if the battery does not cause camera damage, a swollen battery will continue to decline, not only in capacity but also in safety, and needs to be (properly) disposed of.

EXPANSION
Although the Fujifilm OEM battery is reputed not to swell, it is natural for most substances to expand when they are heated. Because the battery's internal cells are sealed, we would expect some (even if extremely slight), "expansion" during the normal charge process. The OEM battery has a construction which is able to manage this. The two faces of the OEM battery's polycarbonate case (and the internal cell separator) are actually membranous.

The centre thickness of this flexible membrane is only 0.25mm (9.8 thousandths of an inch). It's thin enough that light will pass through it.

As well as this, the membranous surface is concave (curving inward) in shape, with the centre of the faces shallower than the edges of the case, by about 0.3 mm on each side.

This thin and flexible construction gives a case that is able to expand slightly in its middle thickness, without actually altering the nominal specifications. Therefore, any slight expansion (not enough yet to be considered "swelling"), by the OEM battery, can be accommodated. The practical difference between expansion and swelling, is that expansion is reversible (the deformation to the cell case has not exceeded the case material's elasticity yield-point), while the deformation of swelling has "passed the point of no return". In theory, the OEM battery could expand by up to 0.6 mm in its middle thickness, and still maintain the full 0.5mm "play", and without making any difference to the battery's fit in the chamber, or to its ease of ejection.

DELIBERATION
The risk of battery swelling is one of the main arguments used by the proponents of the "only use OEM batteries" position, and for some people, is a deal-breaker with regard to using 3rd Party batteries. However, that risk may be mitigated by, over-heat protection while charging, avoidance of in-camera charging, living in a cold climate, and your own careful attention to the condition of the battery, and to any changes it displays. Also, check on-line forums for whether a particular brand of batteries has a reputation for swelling (some do).

[ 6 ] POWER CAPABILITY

Whereas energy capacity (in Watt-hours) is concerned with the battery's capacity to store electrical energy, power (in Watts) is concerned with the ability to deliver that energy, for use. The ideal is that all of the released energy should be available to power the camera, but due to various inefficiencies, some energy is always lost as heat.

In the following, the ability to release high usable power, while limiting heat related losses, will be referred to as the performance level of the battery. The Fujifilm X-series camera batteries have evolved from a standard performance level (the NP-W126) to a higher performance level (the NP-W126S battery). The newer NP-W126S battery, replaces the NP-W126, even though its higher performance level is not required by the older (pre-XT2) X-series cameras. Importantly, there is no difference between the two battery types, in either energy capacity or coulometric capacity, since this performance issue is related to battery heating, and the battery's rate of power delivery.

PROPRIETARY INFORMATION
How the battery's manufacturer, Panasonic Energy, was able to realise the performance increase, is proprietary information. However, the problem that they addressed would typically have involved one or several of the three electrochemical overpotentials or polarisations (activation polarisation, concentration polarisation, and ohmic polarisation) which reduce a battery's power efficiency, and ultimately lose electricochemical energy as heat. Considering that the physical and electrical specifications of the type "S" battery remain unchanged from the original, the improvement strategy most likely involved the use of electrolyte additives to improve the battery's electrochemical efficiency. Whatever the precise improvement strategy, such information is rightly considered an industrial secret, so it is not a situation where the competitors can simply copy and apply the same solution.

" S" VERSUS "NON-S"
In practice, the higher performance "S" battery can work at power levels where the standard performance battery might not be able to keep up with the power demand. The standard performance battery's failure to meet that demand, may even trigger a camera lock-up event.

In order for the latest high-performance cameras to know whether the loaded battery "can deliver" in these high demand situations, the batteries have a way of "signalling" their class of performance level. This information is supplied over the battery's [S] terminal. After assessing the type, the camera indicates the type to the user, by way of alternative colours (yellow or white) for the battery level indicators, and by way of a possible advisory message at power-up time, on cameras where the difference matters (such as X-H1 and X-T3).

YELLOW OR WHITE
When a battery is loaded into a capable high-performance camera (X-H1 or X-T3), the camera interrogates the resistance on the [S] terminal of the battery. If the resistance is 100kΩ, the camera determines the battery to be either an OEM NP-W126 battery, or a 3rd Party equivalent, and the battery level display is in yellow. However, if the resistance shows as 680kΩ (thus exceeding a set resistance threshold), then the camera determines the battery to be an enhanced power delivery capable NP-W126S battery, displayed in white.

In this second case (NP-W126S), I did not say, "or a 3rd Party equivalent", because it is still uncertain whether there really are 3rd Party batteries that can provide the same performance level as the OEM NP-W126S battery. Definitely, 3rd Party batteries are coming onto the market, claiming to be NP-W126S equivalents, and even registering as such when inserted into an X-H1 or X-T3 camera, however, there is more to this than meets the eye.

" S" RESISTANCE
The original OEM NP-W126 battery showed a 100kΩ resistance at the [S] terminal, so the power management boards of 3rd Party batteries implemented a 100kΩ resistor to give the same reading on the [S] terminal as the OEM batteries did. That made sense, because the 3rd Party batteries were intended to be an interoperable alternative to the OEM batteries.

Now, however, we have a situation where the OEM type "S" battery (with enhanced performance) gives a 680kΩ resistance at the [S] terminal, which indicates that it is a type "S". The problem is, the manufacturer of a non-OEM battery (still using the previous, standard performance chemistry), can substitute a 680kΩ resistor for the the protection board's 100kΩ resistor (or simply omit the resistor, and leave the [S] terminal open-circuit). A battery with the appropriate [S] terminal resistance can pass itself as a high performance version, although the only thing changed was the "signalling" resistor.

EASILY MANIPULATED
You can verify that the type "S" indication can easily be manipulated, by placing a small piece of tape over just the [S] terminal of a "non-S" type battery (either OEM, or 3rd Party). This makes the [S] circuit an "open circuit", and changes the resistance to a virtual "infinite resistance", which (by definition) exceeds the set resistance threshold for type "S" indication. Insert the battery into an X-H1 or X-T3 camera, and, Voilà! Now the battery registers as an NP-W126S battery, it shows a white battery level indicator rather than yellow, and the several seconds duration "PLEASE USE NP-W126S BATTERY, etc" advisory message does not display, even though the battery has the chemistry of the standard performance type.

RELIABILITY OF "S" INDICATION
Fujifilm cameras are designed to be used with Fujifilm OEM batteries, and the purpose of the [S] terminal reading is to differentiate between different types of Fujifilm OEM batteries, not to differentiate between OEM and 3rd Party batteries. So the [S] terminal implementation gives reliable information when Fujifilm OEM batteries are used. But, the "S" indication cannot absolutely be relied upon when 3rd Party batteries are used. Just because the label on a 3rd Party battery states that it is an NP-W126S equivalent performer, does not mean that it is. And just because a 3rd Party battery registers in an X-H1 or X-T3 camera as an NP-W126S, does not mean that it will give equivalent performance to the OEM battery. Although 3rd Party manufacturers may be able to boost their battery performance to be equivalent to the OEM NP-W126S battery, the "equivalence" will depend on their performance , not on their in-camera battery indication. As an example of this unreliability, note the anomaly displayed by this pair of, otherwise identical, batteries:

A 3rd Party battery's "S" designation, is not a reliable indicator of its performance. It may be higher performance, or it may just be print and electronically labelled as such. At the moment (early 2019) I am inclined to ignore any 3rd Party battery's claimed "S" designation, and rely on my own assessment of the battery's performance.

DELIBERATION
It is not proven yet, that non-OEM batteries are able to achieve exactly the same power delivery rate as the Fujifilm OEM battery, and type "S" claims on 3rd Party batteries should be treated with caution. However, inability to achieve true type "S" performance may not be relevant, if you don't actually need it. Type "S" performance is not required by all X-series cameras, and Fujifilm even states that the cameras prior to the X-T2 will not benefit from the higher performance level. Furthermore, even if you have a camera which can benefit from the performance improvement, your own shooting style may not. If you use your camera mainly for landscape photography, for example, you are unlikely to require that performance level. If you don't shoot 4K video, if you don't use high rate continuous shooting, and if you don't have continuous auto-focus turned on all the time, you probably don't require the higher performance level. Remember, the standard performance level does not mean that you get less capacity.

[ 7 ] SELF DISCHARGE

Even without being used, a battery is always in a state of running down. All batteries are subject to a deficiency known as self discharge. An elevated level of self discharge is experienced as a charged battery which is unable to retain a high level of charge over a period of days or weeks, when not being used. The cause is an internal current flow called leakage current. Part of the leakage is due to inefficiencies in the battery's electrochemical makeup, and part is due to leakage through the protection board's circuitry. Self discharge is also highly dependent on ambient temperature, with higher self discharge rates occurring at higher ambient temperatures. Exposure to temperatures beyond the normal operating range (ie, above 45°C / 113°F) will increase the battery's future self discharge characteristics, even at normal temperatures. A low rate of self discharge is a desirable quality in a battery. A commom criticism of 3rd Party batteries is that their self discharge rate is higher than that of the OEM battery. Please note, that a battery installed in the camera body, will experience increased discharge while not being used, due to stand-by current (while awaiting a power-up signal from the camera's on-off switch), and due to powering the cameras clock-calendar. This is discharge by the camera, rather than self discharge.

BENCHMARK
A normal rate of self discharge after full charging, would be 5% loss in the first 24 hours, and a further 5% loss (2% intrinsic and 3% due to the battery's management board), over the rest of the month. So at the end of one month, the battery should still have 90% of its fully charged capacity.

MEASUREMENTS
A standard method for measuring self-discharge is to perform a standard charge, store the battery for 30 days at 25°C±0.5°C, and then perform a standard capacity test. Because there is a relationship between open circuit voltage (the voltage you would measure when the battery is not in the camera) and State of Charge (the capacity remaining), an alternative method is to to monitor a battery's open circuit voltage (with a digital multi-meter), at regular intervals over a period of days and weeks. A good result would be approximately 14 milliVolts decrease per day, after the first 24 hours.

DELIBERATION
Because self discharge reveals itself over time, photographers who charge their batteries just before use (so there is no interim period between charging and usage), may not be affected by moderate degrees of self discharge. However, in advanced cases, the loss of charge may be noticeable over a period of hours. Battery self discharge is a fact of life. The question is whether the 3rd Party battery can equal (or perhaps even better) the low self discharge characteristic of the Fujifilm OEM battery.

[ 8 ] BATTERY AGEING

All batteries decline in their capabilities over time, and eventually reach a point where their ability to perform does not meet the user's needs. In other words, batteries age and die (or at least, start to give unacceptably low performance). This process consists partly of a time driven element (calendar fade), and a usage driven element (cycle fade). A common criticism of 3rd Party batteries is that their service life is shorter than that of the OEM battery.

CALENDAR FADE
Even if you never use the battery, it has a limited calendar life. As a general rule, the capacity of an unused battery will reduce to about 80% by the time it has reached two years of age. However, because you are probably using your batteries, rather than keeping them in extended storage, cycle fade (which accompanies battery usage), will be of more interest to us.

CYCLE FADE
A battery's charge retention steadily declines through successive usage cycles over a period of months or years. One whole cycle refers to one charge period plus the following discharge period. The typical test condition is fully charging at 0.5C to a voltage of 8.4V, and then, discharging at 0.5C to a voltage of 6.0V. The cycle life is the number of cycles which can be made before the discharge falls below a set percentage of the rated capacity. A reasonable expectation (for mirrorless camera batteries), would be about 80% capacity after 300 cycles, and 70% capacity by 500 cycles.

It is difficult to assign a time-frame to cycle referenced usage, since this will differ according to the particular photographer using the battery. Fujifilm states that the NP-W126S battery should be good for at least 300 cycles. On the basis of this 300 cycle expectation, if you charged and ran down your battery every day for six days of every week, the battery would barely last one year, before hitting the 80% mark. However, a photographer with such heavy battery usage, is likely to have more than one battery, (with some batteries being charged while others are in use), so that in practice, you may still find that it takes more than 2 years for an individual battery to reach 300 cycles.

The 300 cycle specification does not mean that at 300 cycles, the battery is "dead"; rather, it means that by 300 cycles, because the battery only retains 80% of its original capacity, it may no longer be performing up to the photographer's expectations. For example, on a shoot that could normally be completed on one fully charged battery, you may now have to do a battery change before the end of the shoot, if the battery is showing signs of cycle-fade.

BENCHMARK
As a service life benchmark, an OEM Fujifilm battery can be expected to give four or five years of service. About two years of primary service (top capacity and performance, suitable for professional needs), and about two to three years of secondary service (declining, but still good, capacity and performance, suitable for more casual photography, or for back-up use). The service life has effectively ended when the battery gives an unacceptably small number of shots, or it just won't hold a charge. When comparing 3rd Party batteries to OEM, we should frame the comparison within the context of the four to five year lifespan of the OEM batteries.

DELIBERATION
Because battery ageing takes place over a period of at least months, it is not something that you can assess instantaneously, or within a short period of the purchase time. You mainly get this information from your own extended usage experience, or that of others. Comments such as "I have been using this battery for a while, without any problems", are unfortunately, so imprecise as to be virtually useless. More objective feedback with reliable numbers (such as months of service, charges per month, and typical number of shots per charge), from other battery users (either colleagues, or via on-line forums), is invaluable in making a pre-purchase assessment. Again, the question is whether the 3rd Party battery can equal (or perhaps even better) the long service life of the Fujifilm OEM battery.

[ 9 ] CONTROL CODES

Control codes (or production codes) are an important part of battery manufacturing quality assurance. Although there may be codes on internal components of the battery (and therefore, not visible to the user), the codes of interest to the user, are any codes marked on the case of the assembled battery.

These sequences allow the manufacturer to track such details as a battery's date of production, production batch, production line, region of destination, or other pertinent information. If a battery is found to be faulty, with a systemic fault that may affect other batteries of the same production batch, these codes are necessary to be able to distinguish affected batteries from the rest of the production cohort.

RECALLS AND ADVISORY NOTICES
Control codes allow after sales follow up, in cases where a product batch has been found subject to quality issues. These do happen. In February of 2012, Nikon initiated a voluntary replacement scheme, for specific batches of their EN-EL15 batteries, due to the possibility of the the battery overheating, and the exterior casing becoming deformed. Such a replacement scheme is only possible, because batteries from the affected production batches can be identified, by way of their lot numbers.

PRODUCTION DATE
A cheap battery may turn out to effectively be an expensive battery, if you find that you purchased stock that is several years old. Even though it has never been used, it may now be past its prime, due to calendar fade. Lithium-ion batteries are at their best for about two years, post manufacture. After that, a decline in performance starts to become apparent. With many 3rd Party batteries, their age since date of production is generally not discoverable, and we have to make assumptions about age based on their purchase date. A feature of the Fujifilm OEM batteries is that their production date can be precisely determined.

This is useful, not only for projecting future performance expectation, but also for avoiding overly-old batteries at time of purchase. (Taking into account distribution and logistics matters, up to several months past the production date would seem an acceptable age for a "fresh" battery).

DELIBERATION
Control codes can contribute to our level of confidence in the battery, and as such, can deliver a user-experience type advantage. It affects how you feel about your new battery acquisition in terms of confident expectation that this is a quality battery, with a probable long service life. If it is important to you to ensure that newly purchased batteries are as fresh as possible, and if you can inspect the battery before purchase, OEM batteries, because they can be accurately dated, may have an advantage. Without the ability to date the battery, 3rd Party batteries may have a degree of chance attached to their purchase, especially if the vendor has a low or unknown turnover rate.

[ 10 ] WARRANTY

There are two different warranty issues. One is the warranty on the battery. For the OEM battery, this may only be several (maybe 3) months, depending on your regional Fujifilm office. Among the 3rd party providers, you can find a few that offer a clearly spelled out warranty (in one case, 3 years). But for most of the 3rd Party providers (particularly unbranded, or little know brand batteries), there may be virtually no warranty. The battery's vendor might replace an early failure battery, but mainly as a matter of goodwill, and to preserve good feedback.

CAMERA WARRANTY
The other warranty issue is to do with how using a particular battery could affect the warranty on the camera. If a camera, still under warranty, was damaged due to a defective battery, the camera company would rightly be concerned with the question of whether the battery was an OEM or a 3rd Party battery. Firstly, if the battery was the cause of the damage, the responsibility for the damage should lie with the battery manufacturer, who would not be the camera company, in the case of a 3rd Party battery. Secondly, the camera company typically abnegates responsibility in cases of "failure to follow operating instructions", including the instruction not to use any batteries other than the OEM battery.

For some people, buying an OEM battery, is like paying extra to get insurance, so that they won't have to cover their own repair costs if a defective battery induced problem should occur, while the camera is under warranty.

EXPIRY OF WARRANTY
The warranty issue could be considered a short term, and a transitory issue. Eventually, the warranty on the camera expires, and It could be argued that, if the camera is out of warranty, then the warranty issue is not relevant. This would generally be considered a reasonable position to take. However, if you up-grade your camera regularly, then long term considerations can make this situation a little more complex.

BATTERIES CAN SPAN CAMERA GENERATIONS
Of course, a new camera comes with a new OEM battery, so there is no problem there. However, many people require more than one battery for their camera. As an example, for my X-T3 camera, I currently have 5 batteries (all of them OEM): one in the body, two in the grip, and two spares. One was supplied with the camera, but the other four, still working well, were taken from my older X-T2. The point is, batteries can span camera generations. So even when the X-T2 went out of warranty, there was an advantage in purchasing OEM batteries as spares, because they later ended up being used in a new "under warranty" camera again (the X-T3).

INSURANCE
If you are a professional photographer, who has all of your photographic gear insured, you can effectively bypass the warranty issue, if your policy is comprehensive enough to cover battery failure, or battery instigated camera damage.

DELIBERATION
Statistically, most people will never have to make a warranty claim on their Fuji-X camera. Once the camera is out of warranty, this may not be an issue at all. You may be willing to take the risk of using a battery that, in the perhaps unlikely event that it damages your camera, could lead to you having to pay the repair (or replacement) costs. The probability of this not happening, is on your side. You may consider this an area where, although it's nice to have the security, you are willing to save some money, by taking the chance that this issue does not ultimately eventuate.

[ 11 ] RELIABILITY

Reliability refers to a high level of confidence in a battery, both in terms of safety, and general operability. Battery reliability may be of critical importance to professional photographers, as well as other photographers who are working at a high level of camera expectation, or high rate of workflow. But it can also be relevant to any photographer who would like to have a trouble-free photographic experience. Unreliability can manifest as safety problems or service problems.

SAFETY RELIABILITY
Safety reliability is concerned with the battery's ability to handle various types of accidental abuse. Assurance testing typically covers electrical, thermal, and mechanical types of abuse.

When subjected to these types of abuse, the battery should have a high level of resistance to combustion or explosion, or if the battery does combust/explode, the effect should be relatively contained (ie, not releasing flaming particles, or high velocity projectile fragments).

COMPLIANCE
Certification and conformity guarantee that the battery type has been tested up to appropriate standards. The Fujifilm OEM batteries comply with applicable standards for user replaceable batteries. The current battery displays 5 compliance symbols.

The battery may also be compliant with other standards, which do not mandate display of a symbol or marking (for example, transport of dangerous goods by air, under UN/DOT 38.3). Internally, the OEM battery shows compliance with relevant standards. For instance, the protection circuit board states compliance with UL 94V-0 Flammability Test, as well as carrying the UL Recognized Component mark ("backward R" U).

3rd party batteries frequently carry only the CE marking (which can be self-assessed), or no compliance markings at all.

FAKE CERTIFICATION OR CONFORMITY
Sometimes the certification or conformity markings (particularly the CE mark), of 3rd Party batteries are fake. An un-branded battery could not achieve proper CE conformity, because CE compliance must always be traceable, and someone must ultimately be accountable. Traceability facilitates market surveillance by the regulating authority, and makes the identification required for enforced withdrawals and recalls, possible. For CE conformity, the manufacturer needs to hold documentation, including a Declaration of Conformity (DoC), as well as a Technical File, which is a dossier fully documenting the evidence relating to the product's compliance with the applicable safety standards. Obviously, such documentation (even if it does exist), is not open to scrutiny by the regulating authority, if the manufacturer is anonymous, or cannot be contacted or located. The product is also required to bear a batch, type, serial, or model number, for identification. The following battery lacks the basic features required for traceability. (In this case, it doesn't even state the country of origin).

Other batteries give away their sham compliance by using an incorrect form of the CE mark. The true CE mark has a significant space between the two letters, due to the overlap of the two "construction" circles, underlying the design:

However, on the following 3rd Party battery, the spacing is reduced, and the middle bar of the E letter, is longer than it should be.

This look-alike symbol is sometimes referred to as the "China Export" mark. In terms of indicating conformity to safety standards, it has no real meaning.

SERVICE RELIABILITY
Battery reliability is not only concerned with safety, but also with the ability to complete the task at hand, without undue delays (such as unscheduled battery changes), erratic equipment behaviour, or data losses. Service problems can be: low shot count, "flat-without-warning", high self discharge, short lifetime, and irrecoverable sudden battery failure. Battery failure (including full depletion without sufficient warning), can result in missing a key shot, or sudden stopping of a video sequence without the proper termination and shut-down procedure, resulting in possible data corruption, or even complete loss of the video file. Furthermore, there may be unforeseen events, which will push the camera and battery to the limits of endurance, and we would like to have confidence that the battery can handle these situations.

RELIABILITY OF THE PHOTOGRAPHER
For some professional photographers, it may be the case that use of OEM batteries is effectively mandatory. For instance, the risk of batteries failing during a shoot with no possibility of re-shoots or second chances (the ceremony part of a wedding shoot, or fast paced sporting events photography), could make the selection of battery type virtually non-discretionary. Your clients have a reasonable expectation that you have exercised due diligence in ensuring that their photographic brief can be fulfilled. Missing a key shot, because a battery, which was chosen on the basis of its lower cost, failed without warning, falls below the best standards of professionalism. If you happen to live in an ultra-litigious society, the fact of having used your equipment according to the directions of the camera's manufacturer (including, using the specified battery), may form an important part of your defense, in case of a law suit brought against you, over a photographic brief marred by misadventure, either through failure to capture non-repeatable moments and events, or through accident or injury due to battery initiated fire or explosion. For professional photography, a higher price paid for OEM batteries might just be considered one of the costs of running the business.

TENDERING FOR CONTRACTS
Some professional photographers have experienced that when tendering for the contract of a video or photographic project from a government department, or a major corporate entity, contractual expectations for the tender may include submitting copies of recently developed risk assessments that are relevant to the tender, as well as evidence that equipment is maintained in accordance with manufacturer/legislative requirements. Strictly speaking, equipment needing to meet compliance with safety standards, would also include user replaceable lithium-ion batteries, and it may be that only the OEM battery is able to meet this requirement.

DELIBERATION
When exploring the critique of reliability, there are issues that are very significant for professional and highly specialised amateur photographers, that might not hold the same significance for the casual, recreational photographer. If we think of confidence in our equipment as, "having a good feeling that something bad won't happen", we have to recognise that the "something bad" has a different significance for the high-level pro (where a botched brief or battery-caused injury, could mean lawsuits, loss of reputation, or even bankruptcy), and for the specialist amateur (where it could mean the failure of a long planned and expensive project or expedition), compared to what it means to the casual photographer (where a missed shot may only be a transitory annoyance, and simply written off as bad luck). How important this issue is to you, only you can decide. Once again, you might ask, is the benefit of a high level confidence in equipment reliability, worth the extra battery cost?

[ 12 ] ULTIMATE VALUE

When I say "ultimate value", what I mean, expressed in a few more words, is "Ultimately, it all comes down to the amount of user relevant Value (not necessarily monetary) delivered by the battery". At the very beginning, we looked at battery price, and the differences between OEM and 3rd Party batteries were stark. In order to justify the higher cost, the OEM battery had better deliver a lot of benefits to the battery user.

This is how I have chosen to present summaries for various battery types, in a very visual way, in order to assist "getting your head around" a very complex analysis. Your methods and conclusions may differ considerably. For a final analysis, I have brought together all of the criteria in a single chart, and further grouped the criteria into the categories of PRICE & VALUE, CAPABILITY & PERSISTENCE, and SAFETY & CONFIDENCE. This represents the personal way that I chose, to compile information about different batteries, for the purpose of producing an overview. You may have a method that suits your needs and preferences better. Please note that the selected criteria are by no means comprehensive, and the individual battery user may be in circumstances where other criteria (for instance, cold climate battery performance), may also be very important.

For the PRICE critique, a lower price scores higher, and its line has the related critique of VALUE at the other end. They are the two poles of the consideration: "How much does it cost, but also, how much do I get, for what I pay?" (For our purposes, the VALUE critique has simply been based on an aggregate of the capability, persistence, safety, and confidence scores).

Another line joins the related critiques of CAPABILITY and PERSISTENCE. Capability simply means the ability of the battery to power the camera, for an acceptable period of time, or for an acceptable number of shots. It means the battery has the capacity required by the photographer, and can deliver the performance required by the camera. Persistence means that the capability that we experience now, is able to be sustained into the future, both short term (low self discharge), and long term (long battery service life).

The third line joins SAFETY and CONFIDENCE. Safety should be relatively self-explanatory. But as well as its practical implications, working within a safe system also affects how we feel, while we work. Together with the "confidence" given by using a battery which is specified for the system, (feelings of) Safety and Confidence, operate in the "affective domain". They can allow us to work with a positive and self assured attitude, rather than from a position of underlying apprehension of possible adversity. (For example "I would like to charge this battery in-camera, but I'm afraid that it might swell and get stuck"). In extreme cases, it could make the difference between photography being a fulfilling endeavour, or a stressful task.

This circular arrangement of the criteria will form the basis for a type of graph, variously known as a spider(-web) graph, or as a radar graph. The use of this graphic display is only intended as a tool for exploring the multivariate nature of battery choice, and is not intended as the graphic proof of a universal best choice battery. First, let's look at:

THE PERFECT BATTERY
This battery (which unfortunately does not exist in reality) achieves top scores on all measures, and cannot be surpassed. It is presented here, simply as an ideal to aspire to.

Apart from its perfect scores, the battery's graphic profile is characterised by a "roundness", showing that the battery addresses all relevant areas of critique, rather than concentrating on some and neglecting others. In terms of a graphic profile, this is the type of result that we would like to achieve.

THE FUJIFILM OEM BATTERY
This battery scores very well on all areas of critique, apart from price. Note that it never achieves full possible scores, in recognition that, in reality, there is always room for further development and improvement.

This would be a very well rounded battery, if not for the high (low scoring) price. The high price is testimony that research and development, materials selection, quality management, and achieving safety accreditations, all come at a monetary cost. You pay a lot, but you do get a lot for it. The question is whether some of those benefits (which you have paid for) are superfluous to you personal photographic needs (for instance, warranty implications, and accurate battery level display). It could be claimed that the price is out of proportion to the value, and this is reflected in the distortion of the shaded area of the chart, deviating from the roundness of the "perfect battery". What do you think?

TOP-TIER 3rd PARTY BATTERY
These batteries are in the highest price-group of the 3rd Party batteries, and are generally highly respected. It is rare to hear bad reports about them. (Note that this group excludes those batteries that have a reputation for swelling, or an overstated capacity).

Safety has been marked down because the battery's lack of thermistor is a compromising factor whenever the battery is charged in a Fuji charger, or charged in-camera. The capacity and persistence, which are the most obvious day-to-day criteria for battery worth, are good. For the price, we get a well rounded battery, and a good solid performer.

LOW COST 3rd PARTY BATTERY
These batteries deliver decent short term operability, at a very competitive price. However, over a longer time frame, their deficiencies begin to show. (Note that a lower capability score may simply indicate smaller internal cells, rather than being a reflection on the cell quality).

Over time, high self discharge, swelling, high cycle fade, and ultimately, short service life may become apparent. The low price is achieved partly through cutting production costs, which is seen along the SAFETY-CONFIDENCE line. Safety can be compromised by, for example, using soldering for terminal connections, rather than welding, and by using adhesive tape as an insulating cell-separator, rather than the specially designed cell-separator of the OEM battery. The graphic profile of this battery type is unbalanced, and very "un-rounded". And yet, for some photographers, this battery suits their photographic needs, without incurring the extra costs of "benefits" that may produce little "real" difference for them. If you have a few of these batteries in your bag, then if one fails or misbehaves, just swap in one of the other back-up batteries. This is a practical type of reliability, achieved at a low cost.

DELIBERATION
I have tried, throughout this exploration of battery issues, to present mainly evidence based information, and avoid too much conjectural discussion. Yet, I am very aware that my analysis of a battery type's worth, may differ from that of another experienced photographer, and I respect the value of the differing viewpoints. I hope that I have given sufficient technical material for the reader to arrive at their own informed judgement about which battery type (OEM or 3rd Party) represents the best choice for their own personal photographic style and needs. There is no universally correct answer, but there is an individually appropriate one.

THE DECISION

That bell marks the end of the final round. You 've watched the battle. You've witnessed the blows. Now it's time to make YOUR decision. Will it be the Fujifilm Champ, or the 3rd Party Contender?

And the winner is . . .

Thanks for reading -

THE GREAT BATTERY BRAWL

[ Last updated: 25 July 2019 ]

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Fuji NP-W235 Battery

… Making sense of the numbers

‚‚The NP-W235 is the new battery for the recently released Fujifilm X-T4 camera. The following compilation of battery characteristics is taken from "nameplate" specifications (on the battery label), and published specifications (mainly X-T4 Owner's Manual), as well as some independently derived specifications. Explanations of the interpretation and significance of the various specifications are also given. For convenience, key points are noted for most sections.

Given that the new battery's double-curved face is not very suitable for printing, most information is contained on the under-surface of the battery (unlike the NP-W126S battery which was able to use both front and back surfaces). The NP-W235's under-surface displays specifications and safety warnings, and some standards compliance information, with different sections in English, Japanese, Korean, French, and Chinese. Because of limited space, only the safety warnings tend to be duplicated in the different languages. Other standards compliance symbols are impressed on the top and bottom ends of the battery.

CONTENTS

[ 1 ] Battery Name
[ 2 ] Component Cells
[ 3 ] Capacity
[ 4 ] Voltage
[ 5 ] Nominal Energy
[ 6 ] Dimensions
[ 7 ] Volume
[ 8 ] Weight
[ 9 ] Volumetric Energy Density
[ 10 ] Gravimetric Energy Density
[ 11 ] Charging Temperature Protocols
[ 12 ] Operating Temperatures
[ 13 ] Production Date
[ 14 ] Summary
Appendices

[ 1 ] BATTERY NAME

Fujifilm have continued to follow their naming scheme for multi-cell battery packs, where the battery model number is derived from the battery's capacity. Some older battery models do not conform to this scheme.

The apparent discrepancy between the NP-W235's derived 2350mAh capacity specification, and the 2200mAh actually printed on the battery, will be explained below (refer: Section [ 3 ] CAPACITY ).

[ 2 ] COMPONENT CELLS

The B-profile (or "B" cross-section) of the NP-W235 battery is an immediate clue to what shape cells are inside. In contrast, previous X-series and GFX-series batteries have had rectangular profiles/cross-sections, indicating rectangular-prism shaped (admittedly, with rounded edges) internal cells.

However, the battery also carries a standardised alpha-numeric descriptor string (2INR19/50), which indicates the internal composition of the battery pack, by cell type and size. Note that the descriptor string makes no reference to capacity.

You can find this same 2INR19/50 alpha-numeric string on similarly sized batteries from other camera makers, such as Canon's EP-L6, Nikon's EN-EL15, and Sony's NP-FZ100, for example, although older batteries may not carry this descriptor string.

The NP-W235 battery (like its NP-W126S and NP-T125 siblings), is manufactured by Panasonic Energy, in its Wuxi, China, plant.

The internal cells are most likely Panasonic's NCR18500 cells (model variant still to be identified), which fit the descriptor string. A retrieved copy of the data sheet for this cell, quoted a Minimum Capacity of 1900 mAh, but this data sheet (NNP Series, NCR18500, 2010B-1) was from February 2010. It is not unreasonable to expect the current model variant to be in the 2200 mAh capacity range, after a further 10 years of development.

[ 3 ] CAPACITY

Capacity indicates the battery's capability for sustained transfer of electrical charge. It specifies current per period of time, as milli-Amp hours (mAh). Past models of Fujifilm batteries commonly stated two different capacity specifications on the battery: a Typical Capacity, and a Minimum Capacity.

With the NP-W235 battery, Fujifilm have used a revised terminology for stating capacity (when using English language), which is to specify a Nominal Capacity and a Rating Capacity. These two specifications can be found in the X-T4 Owner's Manual (English language PDF, page 338). We presume that this change only represents a difference in the naming of the specifications, but not in the underlying specifications that are indicated. The terminology differences are contrasted in the following table:

The NP-W235 battery only carries one printed capacity specification, 2200mAh, which is the Rating Capacity. The capacity value which would be determined from the battery name (a value of 2350mAh on the basis of the “235” in the name), is the Nominal Capacity. Note that the label's second occurrence of the 2200mAh value is preceded by the Chinese characters 额定容量 which generally have the meanings indicated in the Term (2) column of the table below.

Term (2) is commonly rendered as "Nominal". (Try copy-and-pasting "translate 额定容量" into your browser, and check the various results). However Fujifilm's NP-W235 English language usage, now renders Term (1) as "Nominal" (instead of "Typical"). The current Fujifilm usage essentially conflates the terms "Nominal" and "Typical". Because of this, we must be careful when making specification comparisons.

The practical difference between the two Capacity specifications (Rating or Nominal), is largely related to intention. The Rating Capacity (or Rated Capacity) can be seen as a more formal expression of the Capacity, and might be used where the intention is to specify a reference class, or to indicate conformity, in situations pertaining to regulations (examples of such would be, safety, statutory, or excise contexts). The Rating Capacity is also the proper specification to use whenever a capacity is required for the determination of other specifications (for example, to determine Energy Capacity). In contrast, the (now called) Nominal Capacity, (formerly referred to as the Typical Capacity), is appropriate for contexts where the intention is to inform user expectation. This capacity value can reflect optimal results obtainable under ideal usage conditions.

The reason Nominal Capacity and Rating Capacity differ in their values, is because they were determined under different measurement conditions. Controlled measurement conditions include discharge rate, discharge termination voltage, and reference temperature. Changes to any of these conditions will affect the outcome of the Capacity test. Recent Fujifilm batteries (such as the NP-W126 class batteries) used different reference temperatures for the Typical and Rated Capacity measurements of their internal cells, with 25°C being used for determining Typical Capacity, and with 20°C being used to determine the Rated Capacity.

Within the standard operational range, the measured battery capacity will be positively affected by increased ambient temperature, and negatively affected by increased discharge rate. This effect is known as capacity offset.

Differences due to testing conditions (in this case, the reference temperature) adequately account for the capacity variations when comparing Nominal Capacity and Rating Capacity values.

However, the main reason for the user to differentiate between Nominal Capacity and Rating Capacity, is to avoid making invalid comparisons between different battery models. For example, make sure that the Typical Capacity of the NP-W126S is compared with the Nominal Capacity of the NP-W235, and that the Minimum Capacity of the NP-W126S is compared with the Rating Capacity of the NP-W235.

[ 4 ] VOLTAGE

Voltage, or electromotive force, is the potential difference that the battery is able to effect across an energised circuit. There are two voltages printed on the NP-W235 battery: a Nominal Voltage, and a Maximum (or Charging) Voltage. The Nominal Voltage (7.2 Volts) is followed by the "solid line over dashed line" (Unicode symbol U+2393), which simply indicates that it is a Direct Current voltage. This 7.2 Volts is the expected Nominal Voltage for a twin cell Lithium-ion battery. The Maximum Voltage (8.4 Volts) is preceded by the Chinese characters 充电限制电压 meaning "Charging Voltage Limit".

Although Fujifilm does not specify a Minimum Voltage, this voltage is implied from the Maximum and Nominal Voltages, since (by definition) the Nominal Voltage lies halfway between the Maximum and Minimum Voltages. Because the battery uses two cells connected in series, the battery voltage specifications are double those of a single cell.

Battery voltage is not a constant, but continuously varies according to the battery's state of charge. Stating a Nominal Voltage is a way of attributing a virtual "fixed" voltage to the battery.

Note that, because the relationship between the battery's voltage and capacity, is non-linear, the Nominal Voltage does not necessarily coincide with the battery's 50% capacity point.

[ 5 ] NOMINAL ENERGY

Nominal Energy, or Energy Capacity, is the rating measure for the amount of energy that is stored in the battery. The Nominal Energy of the NP-W235 battery is 16Wh (Watt hours). It is determined by multiplying the Rating Capacity in Amp-hours by the Nominal Voltage of the battery.

Significantly, the NP-W235's Nominal Energy is even higher than that of the GFX system's NP-T125 (14Wh) battery. The big increase that came with the NP-T125 battery, was its ability to power a higher voltage (10.8 Volt) system.

The NP-T125 (GFX series battery) has been shown for comparison, while noting that the stated voltage and capacity do not produce exactly 14Wh. There is a another possibility, which is, that the NP-T125's Nominal Energy is actually 13.3Wh, and has been rounded up to 14Wh. This is reasonable if the specification is understood in the sense of "The battery's nominal energy does not exceed 14Wh", an appropriate assertion when set in a safety assessment context.

The International Air Transport Association (IATA) safety regulations, require lithium-ion batteries to be marked with the battery's Watt-hour rating on the outside case. The Watt-hour rating is the measure by which lithium-ion batteries are regulated. Batteries, power banks, and devices with batteries inside, are assigned to different risk categories on the basis of the amount of energy they hold (energy which could be released as heat, fire, or explosion). In this context, 100Wh is the significant threshold for being categorised into a higher, more stringently controlled hazard class. The NP-W235 battery (at 16Wh) falls well below this threshold.

When comparing different batteries solely on the basis of mAh Capacity, differing Voltages can be a confounding factor, reducing the validity of the comparison. Nominal Energy is a better specification for comparing the ability of batteries to drive a system, because it takes into account the Nominal Voltage of the battery, as well as the battery's Coulombic Capacity.

[ 6 ] DIMENSIONS

The battery's Dimensions specify its maximum extensions along various axes. The following figures are from the published dimensions of the NP-W235 battery. Of course, whether you consider the longest dimension to be a Height or a Length measurement, depends on the observational orientation of the battery.

This information, however, is of limited usefulness, because of the complexity of the battery's shape, when compared to that of a simple prismatic shaped battery such as the NP-W126S. For this reason, we would like to also take a closer look at the battery's Volume.

[ 7 ] VOLUME

The battery's Volume is not specified by Fujifilm, so it has been derived independently. Volume indicates the amount of space appropriated by the battery. However, with respect to total camera size, the idea that "smaller is always better" may be overly-simplistic, when we consider that a more "substantial" camera, can contribute to a more satisfying (and more sustainable) hand fit, and feel. Knowing the battery's Volume is advantageous, because it can be used to determine Volumetric Energy Density. (refer: Section [ 9 ] VOLUMETRIC ENERGY DENSITY ).

Although the Volume can be measured by displacement methods, I have used a graphical method to estimate the battery's Volume. In contrast to a prismatic battery pack, where it is a simple matter of multiplying its three dimensions, the Volume of a battery pack with complex shape details can be tedious to derive based on linear dimensions. However, if we ignore micro-details (deeming them trivial, in terms of their contribution to the total volume), and look only at the larger-scale shape of the battery, the Volume assessment process can be simplified considerably. If we can determine a cross-sectional area, it is only necessary to multiply it by the height (or length, depending on how you look at it) in order to derive a good approximation of the battery's Volume.

A distortion-free photographic image of the end of the battery, has been used as a surrogate for this cross-sectional shape. Applying a grid method for estimating the area of an irregular shape, a scaled 2 x 2 millimetre grid was overlaid, so that each grid cell represented 4 square mm.

The grid cells were each assessed as to whether they enclosed 0, 1, 2, 3, or 4 square mm (rounded to the nearest square mm) of the shape. Critical squares could be further divided in four equal squares or four equal triangles, as appropriate, in order to facilitate the assessment. In this way, the area of the image shape was estimated.

Based on this grid method, the cross-sectional area is approximately 776 square mm (1.2 square inches). Multiplying this area measurement by the length of the dimension perpendicular to it (52.3mm), gives a volume of approximately 40585 mm³.

The Volume estimate of 40585 mm³, is only 87% of the rectangular-prismatic volume (46386 mm³) which would be obtained by simply multiplying together the Height, Width, and Thickness.

With irregular shape profiles (such as this B-profile), space savings (due to contoured "form fitting" surfaces, for example), may not be able to be fully realised. For instance, the available space may be in locations where, in practical terms, it is of little use. Furthermore, to the extent that a camera's battery chamber might still take a basically rectangular shape, the reduced (due to contours) volume of the battery might be effectively negated. However, apparent "wastage" of potential free space (as air spaces or voids), may still be contributing to design efficiency in other ways, such as heat transfer control. For these reasons, the battery's space demands (how much bearing it has on the size of the camera), probably fall intermediate between the minimum footprint (based on the contoured shape), and the maximum footprint (based on the extreme dimensions of the virtual rectangular-prism shape).

Compared to the NP-W126S battery, the NP-W235 increases Rating Capacity at the cost of some "loss of compactness". Importantly, the Capacity gain offsets and exceeds the loss. Note that the NP-W235's true (not prismatic) Volume was used.

[ 8 ] WEIGHT

Battery weight contributes to the required long term effort involved in supporting the camera during use. However, the idea that "lighter is always better" is possibly overly-simplistic, when we consider that the extra inertia of an appropriately "weighty" camera, can contribute to stability in hand-held usage. The NP-W235 battery weight (from published specifications) is 79g, or 2.8oz. The (presumed) 18500 cells should weigh approximately 34g each, with the balance of the battery weight (about 11g) due to battery case and circuit board. For comparison, the NP-W126S battery weighed 47g total, with each internal cell weighing 20.3g, and the balance of the battery weight (about 6.4g) being due to the battery case, internal separator, and circuit board.

Compared to the NP-W126S battery, the NP-W235 increases Rating Capacity at the cost of some "loss of lightness". Importantly, the Capacity gain offsets and exceeds the loss.

[ 9 ] VOLUMETRIC ENERGY DENSITY

The battery's Volumetric Energy Density is not specified by Fujifilm, so it has been derived independently. The Volumetric Energy Density reflects the efficiency impact of the battery's spatial footprint on the camera size. It is specified in Watt-hours per litre (Wh/l). Provision of increased battery power, typically comes at the cost of increased camera size. If a new battery model has an increased Volumetric Energy Density value, that increase tends to justify any growth in camera size (due to larger battery).

The Volumetric Energy Density is calculated by dividing the Nominal Energy of the battery pack by its Volume. (For reference, one cubic millimetre is 1.0E-6 Liters). It is worth remembering that the total increase in camera size from the X-T3 to the X-T4, is not only due to increased battery size, but also to the inclusion of the new IBIS mechanism.

[ 10 ] GRAVIMETRIC ENERGY DENSITY

The battery's Gravimetric Energy Density is not specified by Fujifilm, so it has been derived independently. The Gravimetric Energy Density reflects the efficiency impact of the battery's mass on the total weight of the camera. It is specified in Watt hours per kilogram (Wh/kg). The provision of increased battery power, typically comes at the cost of increased camera weight. If a new battery model has an increased Gravimetric Energy Density value, that increase tends to justify any rise in camera weight (due to heavier battery).

The Gravimetric Energy Density is calculated by dividing the Nominal Energy of the battery pack by its Weight. It is worth remembering that the total increase in camera weight from the X-T3 to the X-T4, is not only due to increased battery weight, but also to the inclusion of the new IBIS mechanism.

**_[ 11 ] CHARGING TEMPERATURE PROTOCOLS

_**

In order to avoid cell degradation during the charging process, the Fujifilm charging systems (both in-camera and external), switch to different charge rates for different temperature ranges, or even suspend charging if the temperature is outside the allowable range. I will refer to this behaviour as implementing Charging Temperature Protocols. These Protocols are required by the battery, but implemented by the charging device. As an example of how this works, when charging the NP-W126S battery in the BC-W126S charger, if the thermistor resistance (read from the T terminal of the battery) reaches 27 kΩ (kilo-Ohms) or higher, it indicates that the (inversely related) battery temperature is 10°C (50°F) or lower. This temperature is too low for optimal charging, and triggers a charge current reduction from the normal 720 mA (a rate of 0.6 C), to the low-temperature charge current of 420 mA (a rate 0.35 C). These numbers were verified experimentally. The low rate is specified by Panasonic's data sheet for the NP-W126S's internal cells (NCA673440), where it states "At temperatures below 10°C, charge at a 0.35C rate". We expect the charging of the NP-W235 battery to be managed in the same way. The X-T4 Owner's Manual (English PDF, page 309) states that "Charging times will increase at ambient temperatures below +10°C (+50°F) or above +35°C (+95°F)". The reason for the increased charging times, is the reduction in charging rate, for these low and high temperature ranges.

In the past, third-party chargers have not replicated this temperature referenced behaviour, so we wonder, in the near future when we foresee third-party "NP-W235" batteries and chargers becoming available, whether they will observe these temperature based Charging Protocols. Whatever the case, the extent to which third party options are able to implement strategies to avoid cell degradation, will be of importance in determining the suitability, safety, and wisdom of choosing such options.

[ 12 ] OPERATING TEMPERATURES

There is an expectation that Lithium-ion powered digital cameras, like the X-T4, will be operated in a wide range of environmental temperatures. Within this range, the Lithium-ion battery should be able to perform efficiently and safely. The X-T4 Owner's Manual (English language PDF, page 338) specifies the battery's Operating Temperature range as 0°C to +40°C. However, this specification is too conservative in the low temperature range, where Lithium-ion batteries are able to operate at temperatures significantly below freezing (Note, this is for operation, that is, discharge, not charging ). If we consider the NP-W126S battery (also specified as 0°C to +40°C by Fujifilm), we find that Panasonic's data sheet for the internal cells, states a discharge temperature range of -20°C to +60°C. We would expect a similar range for the NP-W234 battery. The upper limit of this range aligns with the maximum temperature of +60°C printed on the battery.

Adding to the perplexity of this matter, on page 337 of the X-T4 manual, under "Power supply/other > Operating Conditions", a temperature range of -10°C to +40°C (+14°F to +104°F) is stated. I would suggest that the 0°C to +40°C range is a recommended Operational Temperature range (and possibly an amalgamation of the safe discharge temperature range, and the safe charging temperature range), while the -20°C to +60°C is the Absolute Environmental Temperature range, for the battery. In general, Lithium-ion batteries can be discharged well below 0°C (although the available capacity will be reduced). When Lithium-ion batteries operate at very low temperature, a typical decrease in efficiency is: while at -10°C the battery can deliver only about two-thirds of its normal capacity, and while at -20°C the battery can deliver only about half of its normal capacity. Although these very low temperatures are not ideal, the batteries can be utilised (but not charged) at these temperatures, and photographers do successfully use them down to -10°C and lower. Operating Temperature range is a specification area where Fujifilm could make further clarification.

A subset of the environmental temperature range is the Storage Temperature range. The X-T4 Owner's Manual (p. 309) states this range as +15°C to +25°C (+59°F to +77°F). This temperature range is to avoid cell degradation while the battery is not being used for extended periods of time. Although not explicitly stated by Fujifilm, the optimal storage temperature is the lower value in the range, about +15°C (+59°F), and the optimal state of charge during storage, is about 40 - 50%.

[ 13 ] PRODUCTION DATE

Mainly for the purpose of tracking production batches, OEM batteries are typically marked with a production number, which can identify the production lot, and possibly also, the date of production. Production lot information may be required for warranty issues, as well as for product safety notifications and recalls. Some standards, such as Korean Certification, require the production year, month, and lot number, to be provided. The new NP-W235 battery (unlike the NP-W126 series batteries, which required a decode-chart in order to determine the production date), follows the NP-T125 (GFX cameras) practice of clearly displaying the production date on the battery.

The first two digits indicate the year, and the second two indicate the month. Production date is relevant to the user because lithium-ion batteries typically give their best performance within a two year period of the time of production. Knowing the production date can assist in predicting when a performance drop-off is likely to begin, and in devising a replacement plan.

Although the X-T4 camera's "battery age" display function, might make knowing the production date superfluous in terms of battery replacement planning, the production date information can still be a useful unique identifier to distinguish between multiple batteries.

[ 14 ] SUMMARY

The Fujifilm X-T series mirrorless cameras have been renowned for their reduced size and weight when compared to DSLR cameras. With the release of the X-T4 and its bigger battery, there is widespread approval of the longer operation times available, but also some reservations about the effects on camera size and weight due to both the IBIS and the larger battery. The following table compares important properties of the NP-W126S and NP-W235 batteries, which affect performance against size/weight trade-offs.

Compared to the NP-W126S battery, the NP-W235 is more efficient, as is evidenced by its higher Volumetric and Gravimetric Energy Densities. This equates to more power for the package size and weight. The modest down-side costs of increased weight and size, are offset by a significant gain in Capacity, at advantage ratios that could not be achieved by simply designing the new camera to hold two NP-W126S batteries, for example.

This survey did not look at shots-per-charge, or video-capture endurance, since, as a matter of not only battery efficiency but also camera efficiency, such investigations are beyond the stated scope of the present study. However, We look forward to being able to test the new battery, in real world situations, where we expect the results to be different from those of the standard CIPA testing. I hope the present work will give users of the new X-T4 camera, a better appreciation of the NP-W235 battery, and contribute to realistic performance expectations.

APPENDICES

TEXT INFORMATION SOURCES

Fujifilm NP-W235 Operating Instructions: BL00005069-100
(日本語, English, Français, Deutsch, and Español)
and
Fujifilm NP-W235 Istruziono d'uso: BL00005069-300
(Italiano, and Pусский)

Fujifilm Digital Camera X-T4 Owner's Manual: BL00005063-201
(English)

TRANSLATION OF THE JAPANESE SECTION
The Japanese printed sections of the battery label read:

電式バッテリー
Electric battery

富士フイルム株式会社
Fujifilm Corporation

使用後は、リサイクル協力店へ
After use, take to a recycling center.

危 険 :
Danger:

大険・ 発熱、発炎、破裂の原因となるので、火・水中投入、加熱、分解、ショートなどしないこと。
Do not throw into fire / water, heat, disassemble, or short-circuit as this may cause serious injury, heat generation, fire, or rupture.

高温での充電、 使用、放置をしないこと。
Do not charge, use or leave at high temperature.

専用充電器以外で充電しないこと。
Do not charge with any device other than the dedicated charger.

TRANSLATION OF THE CHINESE SECTION
The lower four lines of the battery label (written in Chinese), read:

富士胶片株式会社
Fujifilm Co., Ltd.

锂离子电池组
Lithium-ion battery pack

型避:NP-W235
Type: NP-W235

中国组装
Assembled in China

充志限制电压 :8.4V
Charging voltage limit: 8.4V

额定容量 :2200mAh
Rated capacity: 2200mAh

注意:
Note:

禁止拆解、手击、挤压或投入火中。
Do not disassemble, strike, crush or throw into fire.

请勿置于高温环境中。
Do not place in high temperature environment.

电池浸水后禁止重用!
It is forbidden to reuse the battery after immersion in water!

[Last revised: 18/05/2020]

A NOTE OF CAUTION

The Internet is full of misleading and outright wrong "information". I make every effort to ensure that the information I present is factual, as best I am able to establish. However, there is always the possibility that I have made a mistake, or that my sources are in error. If you are going to use the above information as the basis for important decisions, or use it as a reference source for other informative works, I recommend that you exercise due diligence and seek independent verification of the accuracy of the information presented here.

Thanks for reading . . .

_**Fuji NP-W235 Battery

**_

_If you would like to support me in continuing to produce high quality reference material, like this, please consider donating, maybe even the cost of a coffee.
Ciao!
_

All images © 2020 Dom Varney

Photographic images on this page are licensed under a

Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

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Powering the Fuji X-T3

A SURVEY OF OPTIONS AND STRATEGIES

This comprehensive reference guide assembles information relevant to supplying power to the Fujifilm X-T3 camera, in an optimal way. The level of examination ranges from broad system overviews, to detailed analysis suitable for persons who are using the X-T3 professionally. Although this information is presented within the context of the X-T3 camera, much of it (particularly the information regarding NP-W126 type batteries) is also relevant to other Fuji X-series cameras. I hope that this can help you to get the most out of your Fujifilm camera. There is an important disclaimer at the end of this guide. Please read it before acting upon any information given here.

CONTENTS

A - OVERVIEW

Body only power configuration options
Body and grip power configuration options

B - NP-W126S & NP-W126 BATTERIES

Specifications
Distinguishing between S and non-S
Performance differences
Determining the production date

C - NON-OEM BATTERIES

Genuine vs non-OEM batteries
Discharge characteristics
Identifying counterfeit batteries

D - VERTICAL GRIP

Battery discharge sequence
Battery deployment strategies
9 Volt DC input options
USB boost cable (5V step up to 9V)

E - LITHIUM-ION BATTERIES

State of health
State of charge
Calendar fade
Cycle fade
Detriments to service life
Charging
Charge rates
Charging times
Voltage limits for charge and discharge
Temperature limits
Voltage stabilisation
Measuring battery voltage
Battery contacts
Self-discharge
Storage
Determining the battery's end of life
Li-ion fire hazard

F - POWER MANAGEMENT SETTINGS

View Mode setting
Auto Power Off setting
Power management menu
Boost mode
Performance mode differences

G - EXTERNAL CHARGERS

BC-W126S / BC-W126
Non-OEM chargers
Unexpected Interactions
Over-temperature protection

H - X-T3 USB PORT

Connection mode
Connector types
USB "Power Delivery"
Internal charging
External powering
USB power sources
Fujifilm AC-5VF power adapter

I - POWER BANKS

Advantages
Branded power banks
Port capabilities
Expected output current
Removable battery power banks
Expected efficiency
Multi-voltage power banks
Bicycle light battery boxes
Power banks recommended by Fujifilm
Capacity limits for air transport

J - DC COUPLER

Attachment
9 Volt supply options
D-Tap
Applications & examples

K - Alternative Power Supplies

Automotive power
Buck converters
How to use solar power

L - USB Power Meters

M - Disclaimer

SECTION - A

OVERVIEW

Currently (early 2019), the X-T3 camera boasts the most sophisticated and versatile power management system of any X-series camera to date. Many of its power management improvements were introduced with the X-T2 model. The significant differences between the X-T3's power system, and the very similar power systems of the X-T2 and X-H1, are the X-T3's adoption of the USB-C standard for USB connection, and the ability to achieve maximum performance without having to use the optional battery grip.

The electrical specifications of the X-T3, are found on the identification and compliance plates. The one belonging to the camera body, is at the back of the tilt LCD screen, and can be seen when the screen's top is pulled outward, while the other plate is found on the top surface of the optional vertical grip. Both state that the camera is rated at 9 Volts up to a power of 18 Watts.

In terms of power options, use of the grip adds some, but at the same time, obstructs some others. For instance, while the grip is attached, there is no access to the camera body's battery chamber. Because of this, there are two slightly different power configuration schemes for the X-T3, depending on whether or not the optional vertical grip is used.

When the optional VG-XT3 grip is used, it is possible to leave the grip attached quasi-permanently, since there is no need to access the body battery for external charging, (although, you still have the external charging option, if desired).

Section - B

NP-W126S & NP-W126 BATTERIES

The NP-W126S is the specified battery for the X-T3 system (X-T3 body and optional VG-XT3 grip). Because some X-T3 owners might already have NP-W126 (non-S) batteries from an earlier camera, and they would like to use those batteries in the X-T3, the distinction between the two battery types can become an issue. The newer NP-W126S battery is a higher performance version of the NP-W126 battery, and was introduced to meet the needs of the X-T2 camera. These requirements on battery capability are extended further by the X-T3's even higher performance specification. To the question "Can NP-W126 (non-S) batteries be used in the X-T3?", the short answer is "Yes, but the camera may not be able to perform at its highest specification potential". For some types of photography (for instance, Landscape photography, and Product photography) a reduction in "speed" performance, may simply not be an issue.

The NP-W126 and NP-W126S batteries are identical in terms of physical dimensions and power capacity, and may be considered interchangeable for lower paced situations where top performance is not required.

The specific internal difference between the two battery types is the lower internal resistance characteristics of the "S" version. Low resistance enables high current flow with minimal temperature rise. The readily identifiable visual indicator of battery type is the orange square on the end of regular NP-W126 batteries, and the orange circle (plus the orange insertion direction arrow) on the NP-W126S batteries.

BATTERY TYPE DISCRIMINATION BY X-T3
When the X-T3 is powered up, any battery that is not an NP-W126S (this includes the NP-W126, and non-OEM batteries), is identified. The X-T3 determines the type by measuring for high resistance (about 680kΩ or higher) on the [S] contact of the battery, to indicate an "S" type battery. (If you tape over the [S] contact of a non-S type battery, effectively giving it infinite resistance, the X-T3 will mistakenly recognise that battery as an NP-W126S battery). If three batteries are loaded (1 in the body, 2 in the grip), at power up, the battery symbols for the grip batteries, display briefly with the "three dots" (meaning the battery's state of charge is being assessed). At this stage, the "S" or "non-S" battery type has already been determined, and Left and Right grip battery indicators show in either white (for "S" type) or yellow (for "non-S" type battery).

Within one second, the display shows all three battery indicators, with their appropriate charge levels, and displayed in either white or yellow. Any yellow display (meaning a "non-S" battery is detected), will be accompanied by a message recommending the use of NP-W126S batteries.

Note that the message uses the advisory "Please use …" rather than the imperative "You must use …". This, as well as the fact that the camera continues to work, indicates that the message is to be taken as an recommendation, rather than a directive.

PERFORMANCE DIFFERENCES
The performance differences between the regular and the type-S battery, are to do with sustained high power delivery over time, rather than with stored capacity. The type-S battery was intended to meet the increased endurance requirements of the previous X-T2 camera, when operating in scenarios such as high-rate continuous stills shooting, and long duration 4K video capture. Without the higher performance battery type, sustained high power usage could produce elevated battery temperature, an increase of the battery's internal resistance, and a drop in output voltage, leading to possible camera "lock-up" events. In a lock-up event, the camera becomes unresponsive to all controls, including the on/off switch. Typically, the batteries must be removed and re-inserted before operation can be restored. The NP-W126S battery's lower internal resistance characteristics were designed to address such issues. At the time of introduction (for the X-T2) Fujifilm stated that the improved battery could deliver three times longer duration of continuous shooting, even under 40 ℃ environmental conditions. However, for less demanding usage scenarios, the regular NP-W126 battery should perform satisfactorily, although with limitations to the X-T3's boost mode.

PRODUCTION DATE
The battery's performance potential declines over time, even if not being used. Therefore, in order to assess their service viability, it is useful to be able to determine the age of the NP-W126 class batteries, via their production date. This is recorded via an impressed alpha-numeric code on the end of the battery opposite to the electrical contacts end.

NP-W126 batteries having codes beginning with T, S, R, and P, had 5 characters. For codes beginning with N, and then on all NP-W126S batteries, the code is extended to 8 characters. (Please note that very early versions of the battery, prior to having the orange orientation patch, used a different production code system to the one described here). Of the 8 characters, the first three are the date code, the middle two (usually "1A" or "2A"), are undisclosed production information, and the last three are a manufacturing plant code. Note that Day of Month codes, don't use alphabetic upper-case "I", to avoid confusion with numeric character "1", one. (However, this is not an issue for Year and Month codes, which don't use numbers at all). For similar reasons, zero, "O" and "Q", are not used. To the camera user, it is the first two characters (indicating year and month) that are of interest.

The production date information can be decoded by using the chart below. In the above illustration, the "KGT" date code can be decoded as "2018, July, 26". Note that the year of production code proceeds in a reverse order. As a consequence, a letter closer to the beginning of the alphabet represent more recently produced battery. Since a Li-Ion battery's prime operating condition only lasts about two years it is worthwhile remembering the year codes representing the last two years, since these represent the batteries that are currently within their prime. Batteries beyond the two year period may still be usable for casual photography, but for critical and high power demand usage, batteries within the recent two year production period, should be preferred.

At time of release, the X-T3 should have been supplied with a battery whose production code starts with K. As we get a few months into 2019, production codes starting with J should start showing up.

SECTION -C

NON- OEM BATTERIES

Non-OEM (Original Equipment Manufacturer) batteries are also known as third-party batteries. Batteries that are "nominally" equivalent to the NP-W126, but not genuine Fujifilm batteries, (and therefore, not manufactured by Panasonic Energy Wuxi), are readily available, and at prices significantly below the price of the genuine NP-W126S batteries. Although the nominal specifications may suggest the non-OEM battery as a viable alternative to the genuine battery, there can be significant performance, behavioural, and safety differences.

GENUINE Vs NON-OEM BATTERIES
Although more costly in the short term, genuine Fujifilm batteries offer the following advantages over non-OEM batteries:

Stated capacity is reliable. The genuine Fujifilm batteries are rated at a capacity at or close to the maximum that is attainable for the technology, and their nominal capacity matches their actual capacity. Third-party batteries claiming significantly higher capacities are generally overstated.

The genuine Fujifilm batteries can fully utilise the camera and charger's power management system. This means that all four battery contacts, [+], [T], [S], and [-], are functional. On some non-OEM batteries, the [T] and [S] contacts are either set at a fixed value, or un-connected to any appropriate circuitry. This non-functionality of the [T] (temperature control) could have safety consequences.

The genuine Fujifilm battery's designation as a high performance "S" type, is reliable. Non-Fuji batteries can make this claim, as a pretense, by simply labelling them as an "S" type, and changing the resistance value on the [S] contact from 100kΩ to 680kΩ, without any other internal changes to the "non-S" chemistry or construction. (The camera will report this fake as an NP-W126S battery).

Production date, and so the age of the genuine battery, can be established with certainty. This can be very important for long term power management and planning. Also, if you are able to inspect a battery, before purchase, you could avoid purchasing old stock (bearing in mind that, for distribution and and logistics reasons, we could expect even the "freshest" batteries to be several months past their production date).

There could be warranty implications. If the camera was damaged as a result of a battery defect, obviously the question of whether the battery was a genuine Fujifilm battery, or a non-OEM battery, would be crucial to the outcome of any warranty claim.

Capacity against voltage profile is as expected by the system, so the battery level indicator works as it was designed to.

Extensive information regarding differences between The Fujifilm battery and non-OEM alternatives, is given in The Great Battery Brawl.

DISCHARGE CHARACTERISTICS
The relationship between, battery voltage, remaining capacity, and expected time before power is depleted, is non-linear. The discharge curve for the genuine NP-W126S battery differs from that of other batteries. Unlike the fairly simple curve of the genuine batteries, the discharge curve of the third party batteries tends to be more complex, with multiple inflections. Since the camera's battery monitoring system is calibrated against the discharge curve of the genuine NP-W126S battery, the camera will not read the current capacity of other batteries accurately (unless the battery happens to have exactly the same discharge profile as the genuine NP-W126S battery). Unfortunately, this renders the X-T3's ability to give detailed percent-remaining capacity information for non-Fuji batteries, not very meaningful.

TESTING THE DISCHARGE CHARACTERISTICS
Genuine NP-W126S batteries, and representative non-OEM batteries, were tested in order to establish the discharge characteristics against the battery level indicator. Each battery was fully charged using the supplied BC-W126S charger. When fully charged, the battery was removed and allowed to rest for 90 minutes, so that the open-circuit voltage could stabilise. The voltage was measured and recorded, and the battery was inserted into the X-T3. 4K video shooting was initiated. As soon as the indicator dropped by one bar (an "indicator event"), the video was terminated. The battery was removed immediately, and its open-circuit voltage measured and recorded. The duration of the video recording was used as a measure of elapsed time. The camera and battery were allowed to rest for a 10 minute cooling time, before the battery was again inserted, and video shooting re-initiated, until the next battery indicator event. This process cycle was repeated until the eventual camera shutdown, due to depleted battery.

After testing, I differentiated the results into 3 groups, which I have arbitrarily called type 1 (the genuine Fujifilm batteries), type 2, and type 3. The results for batteries within each type group, have been averaged, in order to give a very generalised view of the discharge behaviour typical of that battery type. Please note that, because the testing placed the batteries under very high stress, the results could be considered as those of a worst case scenario. You may actually get better discharge behaviour than what these results indicate.

TYPE 1 - GENUINE FUJIFILM NP-W126S BATTERIES
Because the battery level monitoring system of the X-T3 is calibrated against the genuine Fujifilm battery, the indicator symbols when using that battery, are informative, reliable, and accurate. Note that the remaining charge percentage and the remaining runtime percentage, don't exactly match, because their relationship is non-linear.

Perhaps most importantly, the indicator gives adequate warning before system shutdown due to battery depletion.

TYPE 2 - TYPICAL HIGH CAPACITY NON-OEM BATTERIES
These batteries are well regarded by some people, because they deliver similar capacity to the genuine Fujifilm batteries, but at only a fraction of the price. However, they have the least conformity to the X-T3's calibration curve. Their actual degree of discharge is always higher than what is shown by the battery indicator, and this discrepancy increases as the battery discharge progresses. By the time the indicator displays 2 bars, the battery is almost fully discharged, and low-battery shutdown follows quickly, with little or no warning.

Notice that this type of battery may not display the one bar battery symbol, but goes straight from two bars to empty.

TYPE 3 - TYPICAL LOWER CAPACITY NON-OEM BATTERIES
These batteries are low cost, and typically have capacities in the range of 1000 - 675mAh, (which may be overstated on their label, by up to 45%). At the beginning of discharge, the actual charge remaining is slightly higher than indicated, then at about midway (3 bars) the display is fairly accurate, and finally, in the low number of bars, the actual charge remaining, is less than indicated. Due to the fact that the battery has a lower maximum capacity to begin with, full depletion is reached very quickly, when the indicator is in the low number of bars. By the time the indicator displays 1 bar, the battery is almost fully discharged. If the low-battery warning is given, shutdown might follow within a couple of seconds.

Because of their lower capacity, these batteries tend to overheat when charging, (the charging current, which has been chosen for a 1260mAh battery, is too high for the lower capacity), and so these batteries often become swollen if the charger does not implement over-temperature protection.

IDENTIFYING COUNTERFEIT BATTERIES
Simply being a non-OEM battery, does not make a battery counterfeit. To be counterfeit, there must be an attempt to deceitfully pass (via fake packaging and labeling) the battery as a genuine Fujifilm battery. Suspicions regarding the battery's authenticity generally arise from, low purchase cost, poor performance, or the experience of the battery having a tight fit in the battery chamber. The following anomalies, (a more comprehensive list can be found in NP-W126S COUNTERFEITS: A Visual Guide to Spotting the Fakes), can help distinguish counterfeit batteries from the genuine (manufactured for Fujifilm by Panasonic) batteries:

Check the dimensions of the printed area of the suspect battery against those of a known genuine battery. When the printed information on the genuine battery was scanned for the purpose of reproduction on the counterfeit, some re-scaling may have taken place, leading to a slight difference in the bounding dimensions of the information printed on the battery.

Weigh the battery, with accurate electronic scales. Genuine batteries weigh very close to 47g / 1.7oz. Non-OEM batteries can be anywhere in a range of about 39-50g.

Check the flatness of the printed sides of the battery. Genuine Fujifilm batteries have a concavity to the sides, which can be seen by placing a straight-edge against them, and viewing against a bright background. The concavity can even be felt by rubbing over the surface with your finger. The genuine batteries will not have flat, or convex (bulging in the middle) sides.

Check the production code information on the end of the battery. Possible anomalies include: non-existent code, non-conforming code, or code that is ink-printed (rather than heat-impressed). In the following photograph, the battery with code starting KGT, is genuine, while the one with code starting MGW (printed in white ink), is a counterfeit.

A counterfeit battery may not show all of these anomalies, but it is likely to show several of them.

Section - D

VERTICAL GRIP

The Fujifilm VG-XT3 vertical grip (from this point on, simply referred to as the "grip") is an option designed to facilitate use of the camera in "tall" or "portrait" orientation, as well as providing further power options to those given by the body alone.

The grip can be used with either two or one batteries, or even without batteries, (if you want the "tall" format ergonomics, but don't need the weight of extra batteries). It can also be used, either attached to, or separated from the camera, as a dual battery charger. Charging takes approximately 120 minutes (when charging two batteries simultaneously) . Note that the Owner's Manual (p. 247), states: "Use only NP-W126S batteries".

BATTERY DISCHARGE SEQUENCE
For battery management reasons, you may sometimes want to prioritise a battery for discharge. As a general rule, the batteries are discharged starting from the left, and working towards the right. For light duty power demand, the three batteries are discharged in the following sequence: First, the left-hand grip battery, next, the right-hand grip battery, and finally, the body battery.

For sustained high power usage (continuous shooting, and high power demand video), the body battery supplements the power supplied by the currently designated-for-discharge grip battery, with the body battery being discharged at a lesser rate than the grip battery. The discharge sequence in this case is: First, the left-hand grip battery plus body battery, next, the right-hand grip battery plus body battery, and finally, the body battery.

BATTERY DEPLOYMENT STRATEGIES
You may be using a mix of batteries that differ in both type and age. The arrangement of the batteries in order of far grip battery to body battery, may have implications for your workflow. Also, certain battery arrangements could, if used for a long period of time, result in some batteries being under-utilised, and others being over-utilsed. For the sake of both efficiency and economy, it may be worthwhile putting in place an appropriate battery deployment strategy.

MIX OF "S" AND "NON-S" BATTERIES
If using a mix of non-S and type-S batteries, it is recommended to place an "S" battery in the camera body. When the batteries are assigned this way, the camera can always have access to the highest performance type battery, even if the other two batteries have become discharged.

EXPLOITATION STRATEGY
The exploitation strategy pushes your best (youngest) battery to the front of the discharge queue. This gives maximum usage value in terms of total lifetime shots against the purchase price of the battery. An advantage is that batteries are never under-utilised, and the strategy is very cost efficient. A disadvantage is that you can start with plenty of power at the beginning of a session, but the second and third batteries discharge more quickly than the first, so you may get less warning when all batteries having become depleted. It's a good strategy if your shoot sessions are typically short.

CONTINGENCY STRATEGY (CONSERVATION STRATEGY)
The contingency strategy pushes your best (youngest) battery to the rear of the discharge queue. It considers the grip batteries as the working batteries, and the body battery as a back-up or contingency battery. Applying this strategy, when both of the grip batteries have become discharged, you should plan to replace or recharge them immediately, rather than continuing to photograph and running down the body battery. This strategy helps to ensure that you always have reserve power, so that you don't lose power at some critical point in shooting, and also avoids having to regularly remove the grip to change a flat body battery, during the shoot. In this strategy, your "best" battery, is being kept in reserve, to ensure that you are able to cope with any unforeseen circumstances. The down side of this strategy is that the "contingency battery" may be under utilized during its typical two years of life expectation. Of course, whenever a new battery is purchased, it takes the place of the reserve battery, and the old reserve battery can be places in the grip as a working battery. This usage strategy is good for long shooting sessions, where you typically have to do battery replacements during the shoot.

ROTATION STRATEGY
This strategy distributes the usage over each of the batteries, so that none of them become overused or underused. This strategy is particularly recommended if you typically don't remove your batteries from the camera and grip (that is, you use internal charging methods). The position of each battery in the system is rotated on a regular interval basis. An ideal interval would be a monthly cycle.

In a (say) five battery system (one in the body, two in the grip, and two spares), the two additional batteries can also be inserted into the rotation sequence, but you may have to do some record keeping, so that you can determine the correct sequence at rotation time. Be aware that, if all of the batteries were of approximately the same age, at the beginning of this strategy, they will all start to show signs of aging (decreased exposure counts) at approximately the same time (about two years on). So this strategy works better if a new battery is purchased at regular intervals (say, at the end of the first year, and then every six months), which should not be an unreasonable demand if working professionally.

9V DC INPUT
A DC power input socket (EIAJ-03) is under the rubber seal on the left-hand side of the grip.

This socket is intended for the AC-9VS power adapter, that is supplied with the grip, and which can be used for both charging and supplying operational power, although not simultaneously. When the camera is turned off, the 9 Volt input will supply power for charging the grip batteries (but not the body battery). If the camera is turned on, then the 9 Volt input will supply power for camera operation.

The camera can operate without batteries if powered via the 9 Volt input, although to attain the camera's highest performance, it may be necessary for the DC input to be supplemented by some battery power, (at least one partially charged battery).

DC INPUT PLUGS
There is the possibility of supplying 9V power using power sources other than the AC-9VS. However, for operation without batteries, the voltage supplied via the DC socket, should not go below about 8.75 Volts; otherwise the display will flash the low power symbol (red battery with no bars), and the camera will auto power-off. The grip's DC input is a standard socket complying with the relevant Japanese standards, and accepts an EIAJ-03 plug.

This socket is not compatible with plugs adhering to the other common standard, which is IEC 60130-10, although one of that standard's plugs will loosely fit the socket in a way that is neither secure nor reliable. If using a 9 Volt power source other than the AC-9VS power adapter, it may be necessary to make up the appropriate cable (soldering and polarity discrimination skills required), in which case, the proper camera-end plug can be identified from the following table:

If searching online, the plug will typically be identified as a 4.8 x 1.7 mm plug. The "signature" yellow plastic tip, while common on the EIAJ-03 plug, is not unique to it, nor is it required by the standards. (In fact, Fujifilm uses a black plastic tip). However, the yellow tip can be a useful indicator of possible-candidates when searching for an appropriate plug.

USB BOOST CABLE
The USB boost cable (5V to 9V step up), is a further option for supplying power via the grip's DC input socket. It is recommended that you only use one battery in the grip when using the boost cable (the reason is given further down). The USB boost cable can be plugged into any suitable USB power source, such as a power bank, a personal computer, or a USB wall convertor. Typically, you would need a 5.5 x 2.1mm female to 4.8 x 1.7mm male adapter or conversion cable, in order to connect the converter to the VG-XT3's DC input socket.

The standard USB 5 Volts is up-converted to 9 Volts, with however, a corresponding reduction in the supplied current. For example, if the power bank can supply 5 Volts at a maximum of 2 Amps (5V x 2A = 10 Watts), then the boost cable won't be able to supply more than about 1.11 Amps of current (9V x 1.11A = 10 Watts) after the voltage conversion. The actual current will be less than this, if we take conversion losses into account, but for practical purposes, we can consider that the current is approximately halved, so 1 Amp. For comparison, the AC-9VS power adapter can supply 9 Volts at 2 Amps (18 Watts). The boost cable delivers sufficient power to supply the camera for moderate power demand stills shooting, and for grip charging of one battery.

If grip battery charging of two batteries is attempted, the boost cable will demand more than the power bank's (typical) 2 Amp total current limit, and the boost cable itself, will be pushed outside its operating limits. This will cause the boost function to fail, with inability to achieve the required 9 Volt supply. To reset the system, the boost cable has to be disconnected, and the reconnected, with the appropriate reduction in current demand. To avoid this problem, it is recommended that one of the batteries be removed from the grip, so that if the grip goes into charging mode, the limits of the boost cable are not exceeded. Unlike power delivered via the camera body's USB socket, input through the grip's DC socket can power the camera, even without any batteries inserted (camera or grip). Again however, keep in mind the boost cable's limit of about 10 Watts of power, whereas for highest level of performance, more than 18 Watts (AC-9VS power adapter plus at least one battery) may be required.

Section - E

LITHIUM-ION BATTERIES

The NP-W126S and NP-W126 batteries are constructed of two series-connected metal-can type prismatic lithium-ion cells, together with a built-in power management board, all of which is sealed in a polycarbonate case.

(In what follows, "lithium-ion" will usually be abbreviated to "Li-ion"). The exact chemical composition of the NP-W126S battery is proprietary information. However, some information can be gleaned from Safety Data Sheets, lodged for the purpose of compliance with international transport regulations.

The exact transition metal component of the positive electrode is not openly specified, but the candidate metals are: Co, Mn, Ni, and Al. In what follows, specific information that was available from Fujifilm and from Panasonic Energy in Wuxi (the battery's normal manufacturer), is supplemented by information which applies to Li-ion batteries in general.

BE CAREFUL - NOT FANATICAL
The following information is intended to assist you rather than burden you. In real life practice, it is not possible to follow all of the best advice, all of the time. We should differentiate between occasional sub-optimal battery treatment, and habitual misuse. Since the battery has a limited life regardless of how carefully it is treated, there is little point in becoming obsessive-compulsive in regard to maximising battery life.

BATTERY STATES AND PERCENTAGES
There are two commonly quoted Li-ion battery states that may both be expressed as percentages. One is the battery's State of Health (SoH), and the other is the battery's State of Charge (SoC).

STATE OF HEALTH
State of Health is a ratio of the battery's present capacity for storing energy, compared to the battery's original capacity at the time of manufacture. SoH speaks to whether the battery is, viable for continued usage, or approaching the state of being considered a dead battery. The expression of SoH as a percentage is more conceptual than practical, because the user usually doesn't have an instrument to directly measure the SoH, and it is typically inferred from the battery's age and performance. By definition, the battery's capacity when new will be 100%, but this percentage will decline with time and usage. We are typically interested in the range from 100% to 80%, because when the SoH reaches a conceptual 80%, there is a noticeable fall-off in battery performance. For the photographer, this fall-off generally manifests as a reduced number of shots per charge, and around 80% is a typical point at which we might consider withdrawing the battery from primary service, and replacing it.

STATE OF CHARGE
State of charge is a ratio of the battery's present actual deliverable energy, compared to its present potential for holding deliverable energy (which is, of course, largely dependent on the battery's SoH). State of Charge is what is displayed by the camera's battery level indicators. When fully charged, the SoC is 100%, but when "flat", the SoC would be reported as 0%. Keep in mind that 0% is relative, and does not mean absolutely zero energy. Li-ion batteries cannot tolerate being at very reduced voltages, and so a certain amount of electrical potential must always be reserved, to keep the battery in a safe electro-chemical state. This reserve is handled automatically by the camera's power management system, and generally need not be a concern of the user. But, as a consequence of this reserve, not all of the battery's electrical energy is available for use by the camera.

To summarise, a flat battery will have a low State of Charge (say 0%) and the remedy is to re-charge it, while a dead (or dying) battery will have a low State of Health (say 80%) and the remedy is to replace it.

BATTERY LIFE EXPECTATION
As a general rule, Li-ion batteries do not suddenly "die", but rather, they show a gradual decline in capability. Within the context of that decline, we can broadly identify a transitional phase when the battery's performance goes from meeting expectations to failing to meet expectations. We can consider the service period up to the "failure to meet expectations" point, the life of the battery. The Li-ion battery's life inevitably declines due to two processes known as calendar fade and cycle fade.

CALENDAR FADE
Calendar fade refers to a time related decline in capacity, which is independent of charge-discharge cycling, and which even affects batteries that are not being used. (Note that calendar fade is also accelerated by high temperatures, so it is beneficial for batteries to be kept cool). The commonly accepted rule of thumb is that, after 2 years, a Li-ion battery can only hold 80% of its original capacity. In general, at 80% capacity, although the battery is still usable, it is noticeably under-performing.

CYCLE FADE
Cycle fade refers to an in-service related decline in battery capacity due to repeated charge-discharge cycling. Fujifilm states an expectancy of 300 charge-discharge cycles for the NP-W126 class batteries (Owner's Manual, p. 274). Again, capacity falling to 80% is the criteria for determining expected cycle numbers.

BALANCED USAGE
If we try to balance these fade processes by aiming for the calendar fade endpoint and the cycle fade endpoint to coincide, (300 cycles distributed over a period of 24 months), we are looking at roughly 3 charge-discharge cycles per week, for a single battery. We can consider this as a hypothetical standard-usage-density for the purpose of determining whether the battery is being over or under utilised.

NEW BATTERIES
The Owner's Manual (p. 28) states: "The battery is not charged at shipment." New batteries are delivered with approximately 30% SoC. This is partly to extend service life by keeping the battery in a preferred storage state until the user has taken delivery of the battery, and partly due to transport regulations, (specifically, transportation by cargo aircraft under UN3480, Class 9 Dangerous Goods category, with state of charge not exceeding 30%), since Li-ion batteries are safer (less likely to enter a thermal-runaway condition if subjected to elevated temperatures) at a lower SoC. The new battery may have to be charge and discharge cycled about three times before it gives normal charge and discharge behaviour. This is because Coulombic efficiency (the ratio of the total charge extracted from the battery to the total charge put into the battery over a full cycle), improves with cycling. Previous to the battery being cycled, its Coulombic efficiency may have been between high-80's to mid-90's percent. After a small number of cycles, it can approach 99% or higher. Some batteries have already been cycled by the manufacturer, before delivery.

DETRIMENTS TO SERVICE LIFE
The following situations or conditions should be avoided to ensure that the Li-ion battery is not un-necessarily stressed.

• Avoid high temperatures (should not be subjected to > +45°C or +113°F)
• Avoid ultra-fast charging (Rate of charge greater than 1C)
• Absolutely avoid charging at temperatures below 0°C.

CHARGING
Li-ion batteries are charged according to the constant voltage (CV) / constant current (CC) method. The charge process has two main phases. In the first phase, the current is constant, at a value determined by the selected C-rate, the voltage steadily climbs, and the increase in charge, over time, is linear and rapid. In the second phase (saturation phase), when the maximum charge voltage (8.4 Volts) has been reached, the voltage becomes constant, the current drops rapidly, and the increase in charge, over time, becomes non-linear, and slower. If charging is being monitored, the rapid drop in current is a good indicator of the position in the charge process. Charging terminates when the current drops below a threshold (0.1C is typical).

CHARGE RATES
Battery charging times are mainly dependent on ambient temperature and charging rate. Charging rate, or C-rate, is the expression of charging current normalized against battery capacity. For example, when charging with a rate of 1C, a 1200mAh capacity battery would be charged at a current of 1200mA, and would be fully charged in 1 hour (theoretically). Note however, that a rate of 1C is considered to be higher than optimal, and the recommended fast charge rate is 0.7C. Because very high rates of charging are detrimental to the long-term condition of the battery, high-rate charging is usually terminated earlier in order to avoid detrimental effects. As a consequence, the available capacity changes per different C-rates, with the higher C-rates typically producing slightly less available capacity.

CHARGING TIMES
The X-T3's different charging methods use different charge rates, and as a result, have different charging times. Of the available charging methods, charging via the grip uses the highest rate, and can charge two batteries simultaneously. Charging via the camera body's USB port (if not using USB PD or "Power Delivery") has the lowest charge rate and, although the slowest method, is probably the best for the battery, both in terms of available capacity, and long-term battery health.

If using an external power monitor, be careful not to confuse input current with charging current. You can avoid this problem by working in Watts (current x voltage). For a USB input, the voltage will be 5 Volts (even for USB PD). For charging, the voltage will be 8.4 Volts. USB PD is explained more thoroughly in Section H, about the X-T3 USB Port.

PARTIAL CYCLING
Li-ion batteries do not have any significant memory effect, so there is no absolute requirement for Li-ion batteries to be fully-cycled on a regular basis. They can be partially cycled, but be aware that the various part-cycle patterns can differ in their beneficial or detrimental contribution to long term battery health. Ironically, (and different from many other battery types), the "fully charged" state is more stressful to the Li-ion battery than lower states of charge, and leaves the battery more susceptible to electrolyte oxidation, which is cumulatively detrimental to its life, each time the fully-charged state occurs. Therefore, full cycling (fully charge, then fully discharge), is preferable to "top-up-to-full" partial cycling, because, in the long run, it results in fewer instances of being "fully charged".

If you know that a shoot will only require a small number of shots, (perhaps a couple of dozen), then there is no problem with giving a discharged battery a shorter charge , say 40 to 60% of full capacity. Routinely charging the battery to slightly less than full capacity (90% would be ideal), has a beneficial effect on battery longevity. However, the reduced number of shots per charge is not acceptable to most photographers.

VOLTAGE LIMITS FOR CHARGE AND DISCHARGE
Automatic chargers should implement protections against over-charging, and the camera should implement protections against over-discharging. The battery also has its own internal protective circuit to guard against over-discharging. Limits are according to the following significant voltages:

Although there are automated systems in place to guard against over-charging and over-discharging, poor usage practices can effectively put the battery slightly into the over-charged / over-discharged state. Slight over-charging can result from repeatedly putting an already fully charged battery back on the charger. Slight over-discharging can result from repeatedly turning on again, a camera that has displayed the battery empty sign and automatically switched off.

TEMPERATURE LIMITS
Li-ion batteries are noted for their wide range of operational temperature compared to many other battery types, however, they are very sensitive to temperature beyond that operating range.

As temperatures become elevated, initially the battery sustains internal damage which impacts its long-term performance, then at very high temperatures, the battery starts to sustain damage which can pose serious safety risks. Li-ion batteries contain flammable electrolyte that may vent, and spontaneously ignite when subjected to temperatures above +150℃ or +300°F. When ignited, Li-ion batteries can burn rapidly with flare-like burning effect, and may ignite other batteries in close proximity.

VOLTAGE STABILISATION
After a full charge, the open-circuit voltage of the battery (as checked with a multi-meter) will decrease rapidly in the first 10 minutes and then gradually over the next few hours before stabilising. If you intend using voltage as a guide to battery condition, rest the battery for 90 minutes after charging, before measuring the voltage. The stabilised voltage is a better indicator of SoC than the voltage measured immediately after charge termination, and you are likely to get better power metering by the camera if you begin using the batteries after they have stabilised. This supports the practice where, if you have to charge batteries for a shoot, it is preferable to charge them the night before the shoot, rather than immediately before the shoot.

MEASURING BATTERY VOLTAGE
If you have the requisite background knowledge, and are comfortable with using a digital multimeter (DMM), you can use the battery's open-circuit voltage as a surrogate for battery state and condition. Since these measurements do not assess the battery under load, they cannot account for load related voltage drop, however they are useful in giving further information for battery assessment and comparison. It should be noted that instantaneous voltages during charging, and instantaneous voltages during discharging display hysteresis. That is, they follow different curves, showing discrepancies in the region of up to half a Volt, with lower voltages presenting for the discharge curve. Therefore, voltages during charging and during discharge are not suitable for comparison.

When doing these static measurements on the battery, the only contacts of interest will be the positive and negative contacts. For measuring the open-circuit voltage, set the DMM to DC voltage measurement, and make contact with the probes for just enough time to get a stable reading. Measurements should be made to the nearest tenth of a Volt.

NP-W126 BATTERY CONTACTS
The NP-W126 class batteries have four gold-plated electrical contacts, marked with [-], [S], [T], and [+] symbols.

The [T] contact pertains to temperature management, and should connect to an NTC (negative temperature coefficient) thermistor, with a nominal resistance of 10kΩ at 25°C (±5% or better, typical). The resistance of the thermistor drops (with a non-linear output) as temperature increases. [To give an example: The NP-W126S battery was temperature stabilised at the room temperature of 15°. The resistance reading from the thermistor was 13.5 kΩ. Then, the battery was placed under the armpit for 5 minutes, to warm it. After warming it, the thermistor reading was found to have dropped to 9.5 kΩ]. The thermistor allows temperature monitoring while charging. Li-Ion batteries typically increase 5°C (9°F) in temperature during charging, as a normal consequence of the chemical process involved. But, the battery should not be allowed to increase more than 10°C (18°F) during charging, nor is charging allowed at more than 45°C, or less than zero°C, in order to avoid shortened battery life, lithium plating at the anode at sub-zero temperatures, and over temperature hazards such as battery swelling, venting, and thermal runaway.

When attempting to charge the NP-W126 class batteries, in the X-T3 camera, or either of the two Fujifilm chargers, if a resistance indicating a temperature within the safe range is not seen at the [T] contact, then charging is not initiated. (This safety function is also implemented on the Nitecore FX1 USB charger). On non-OEM batteries, the [T] contact is usually just connected to a fixed 10kΩ resister (meaning that it always signals the temperature as OK, even if it is outside the acceptable limits). This allows the batteries to be charged, without adhering to the safe charging temperature protocols.

The purpose of the [S] (probably standing for "Status" or "System") contact is not openly documented. The [S] contact most likely accesses a simple system indicator, that gives battery information by whether or not a measured resistance exceeds certain thresholds. Such a method is expandable over time, so that if a new further improved battery became available, another higher resistance threshold can be added to the system, to indicate that battery. Note that the X-T3 camera differentiates between "S" and "non-S" type batteries, by interrogating the resistance on this [S] contact.

SELF-DISCHARGE
Typical self-discharge rates for Li-ion batteries (at a temperature of about 20°C) are 5% in the first 24 hours after charging, and then 5% per month (this monthly five percent is made up of approximately 2% intrinsic loss, and 3% due to drain by the battery protection circuit).

As a rule of thumb, the self-discharge rate doubles with every 10°C increase in temperature.

PLANNED DISCHARGE
Sometimes, we may wish to intentionally either partly or fully discharge a battery, for example, for testing purposes, or in preparation for storage. The X-T3 camera does not provide a specific discharge function (Some cameras do, for example Samsung NX1). For the X-T3, the best way to discharge the battery is through normal usage, just by taking photographs or video. There may be situations where your purpose is only to take the battery's SoC just out of the fully-charged zone (one of the more stressful states of battery condition). For example, you may have charged the battery in anticipation that it would be used, but it turns out that you won't be needing it, and the battery faces an extended period of non-use.

In such a case, you can slightly discharge it by the following method. Put the battery in the currently assigned discharge position (the left-most position if using the battery grip), attach the supplied EF-X8 shoe mount flash unit to the X-T3, and take a few shots using the flash. The EF-X8 has to be used, since it draws its charge power from the X-T3 batteries. (Incidentally, occasional use of the EF-X8 flash, is good for the X-T3's flash capacitor, and helps to keep it "formed"). Another method is to take some video at a high frame rate and resolution (it doesn't need to be 4K video). It is not recommended that you discharge by taking long duration continuous-shooting bursts using the mechanical shutter, because this will cause unnecessary wear-and-tear on the shutter, which although rated at several hundred-thousand actuations, never-the-less has a limited lifetime.

STORAGE
Conditions of storage (an extended period of non-use) have an impact on the life expectancy of the battery. The most significant factors are, the battery's State of Charge (SoC), and the ambient storage temperature. A Li-ion battery's state of least stress is about 40% SoC at 15°C (59°F). This is represented by 2 bars on the X-T3's battery level indicator.

DOWN TIME
If the battery will not be used for several days, or even a week, this period can be considered normal down-time, rather than a storage period. The battery can be left in its present state of charge, although leaving it in a fully charged state is not ideal, and should not be a target for a regular down-time state.

SHORT-PERIOD STORAGE
If it is estimated that the battery will be in a storage condition for a few weeks, "half-charged" is an appropriate level. However, it is also OK to leave the SoC at an effectively "flat" level. A battery which has just gone flat (according to the camera), is still well above any damaging over-discharge voltage. An ambient temperature of +15°C is optimal, but since the period of non-use will be short, a storage temperature in the range -10 to +40°C is OK.

LONG-PERIOD STORAGE
If it is estimated that the battery will be in storage for a period of months (this could happen if you were going to be away from home for an extended period of time, and you are taking a different camera with you), it is recommended to have the SoC of the stored battery at 40 - 50%, indicated by between 2 or 3 bars on the X-T3's battery level indicator. This places the battery in a low stress condition, but also allows for inevitable self-discharge (about 5% per month) to take place, without the battery over-discharging. The battery should not be stored in the camera, due to further discharge by quiescent current. (Quiescent current flows due to the camera awaiting any wake-up signal from the power switch, and also from powering the clock-calendar). An alternative method of assessing a battery's readiness for storage is by measuring its voltage. A battery in good condition will have a stabilised open circuit voltage of about 7.6 Volts when its SoC is about 40%.

If initially stored at 40% SoC, after about 8 months the battery may be close to flat, so it would be good if the stored battery could be given a part charge (back to 40 - 50%), say about every 3 - 6 months. At any rate, a battery should be charged at least once per year. A storage temperature of +15°C is optimal, but up to +25°C is acceptable, however it is not recommended to store the battery outside the range of 0 to +35°C.

KEEPING CONTACTS CLEAN
Keeping the battery's gold-plated contacts clean can help attain optimal charging and usage conditions. Contacts can become dirty from inadvertently touching them, or simply by the deposition of air-borne grime (particularly in cities, where the presence of diesel fuel particulates and other pollutants can be significant). A cotton-tip is useful to buff the contact surface. No liquid or solvent should be used.

Keep in mind that there are numerous contacts in the power supply chain, and they all need to be kept clean. However, be very careful not to catch and bend any spring contacts.

IDENTIFYING INDIVIDUAL BATTERIES
For the purpose of battery management, it is useful to be able to identify each individual battery, by labeling them. No stickers should be attached to the sides of the battery, due to the possibility of jamming in the battery chamber. A convenient place to write (using a fine tipped permanent marker), a number, letter or symbol for individual battery identification, is the orange orientation patch (square or circle) at the end of the battery. The manufacturing year and month code letters are convenient identifiers. Unless several batteries were purchased at the same time, and they came from the same production batch, the production codes are likely to be unique, for each of your batteries.

If you have to use non-OEM batteries, you can put a small sticker in the same position as the NP-W126 class battery's orange orientation patch. Since you probably won't know the production date of the battery, you can arbitrarily assign it a production date three months prior to the purchase date, (this allows for some shelf time with the vendor, before purchase). You can give it year and month code letters, according to the Fuji system, so that any management records follow a consistent method.

DETERMINING THE BATTERY 'S END OF LIFE
A battery is effectively dead when the photographer rejects it due to poor performance. A battery that has been used properly does not suddenly cease working, but it does eventually reach a point where its performance no longer meets the requirements of the photographer. This point will differ slightly from person to person, depending on their usage style and workload demands. Specific signs of a dead or dying battery are:

• Uncharacteristically long or short charging times
• Very rapid self-discharge
• Noticeably decreased number of shots per charge.

SoH LOOK-UP-TABLE
Based on the typical signs of a dead or dying battery, the photographer will develop a feeling about how a particular battery is doing. However, this type of assessment can be very subjective. A more objective criteria of the battery life condition (State of Health - SoH) can be obtained from the stabilised (90 minutes after-charge) open-circuit voltage. It is not possible to give a universally applicable look-up-table (LUT), because battery usage routines (as well as user expectations), and local environmental conditions, will cause variation in the typical voltages reflecting the various states. However, it is possible to compile your own personal LUT over time, if you are prepared to take measurements and keep records. A SoH look-up-table, may be similar to this:

This method is useful if you want to keep records, for comparison, of battery condition at regular intervals, because it yields a number.

BATTERY AUDIT FORM
A convenient way to keep records of battery condition is a battery audit form. This could be either on paper, or a computer spreadsheet. On the form, you record the open circuit voltage (90 minutes after charging), of each battery.

This is done at regular intervals; three monthly (that is, four times a year), would be an appropriate interval. Just do it sometime during the designated month - it is not necessary to do it on a specific date. The form also allows you to record the reaching of significant voltage thresholds (based on the SoH look-up table).

A PDF file of the audit form can be downloaded here: Battery-Audit-Form.PDF

PRIMARY AND SECONDARY BATTERY SERVICE
Batteries that are beyond the two year or 300 cycle stage, although no longer in their prime condition, are still useful. While the best batteries are kept for operating the camera at its top performance (primary service), the aged batteries can be assigned to secondary service tasks. Such tasks include:

• Back-up batteries
• Batteries for short or low shot count sessions
• Hold-over batteries

Hold-over batteries are useful if you recharge all batteries directly after a shoot, in readiness for whenever the next shoot will occur. If the camera is left unused for days or weeks, the first battery in the discharge sequence will lose some of its charge (due to quiescent current, waiting for power-up signal, and maintaining the clock and calendar system). That same battery would maintain more of its charge over the same period of time, if not left in the camera. To avoid this "stand-by" discharge of the battery, when you are not using the camera, you can replace the first battery with an old battery, and just swap in the newer (still well charged) battery, before the shoot.

JUST IN CASE vs JUST IN TIME
"Just in case" and "Just in Time" (JIT), indicate two different approaches to what "triggers" you to recharge your camera batteries. Should you recharge them immediately after a shoot (so that they are ready to go), or should you leave them in their post-shoot state, and recharge them just prior to the next shoot? There is no universally correct answer, because it will depend on your usage style, workload demands, and also your ability to know in advance when the next shoot will be, or even to exercise your own discretion about when shoots will occur. Keep in mind that, when a Li-ion battery has gone flat during a shoot, there is no problem leaving it in that state for some days, or even weeks (just let it have some "down time"). A Li-ion battery is very different from a lead-acid car battery, which should not be left in a discharged state. However, as to the long term affects on battery life, it is probably more beneficial to, where possible, let the immanence of usage be the trigger for recharging (just in time), rather than letting the conclusion of usage be the trigger for recharging (just in case). This is because, with charging directly after the shoot, if you wait some time before the next shoot, the battery has been left longer in a fully charged state (not optimal for battery longevity), and you are likely to give the batteries a top-up charge before the next shoot anyway. This results in more charging than is absolutely necessary. Furthermore, Li-ion battery service life benefits from sustained (many hours to days) relaxation periods following discharge and before re-charging.

BATTERY CASES
Battery cases are useful in order to protect against accidental shorting of the power terminals, and give a convenient means of distinguishing between charged and discharged batteries. Also, in accordance with IATA regulations, pouches or cases are necessary if spare batteries are to be carried (in carry-on baggage only) while traveling by air-transport. New NP-W126S batteries, when purchased as an accessory, are supplied with a plastic soft pouch.

However, if you would like a hard case, those designed to fit the Nikon EN-EL9 battery, are suitable (although slightly longer than necessary). You can cut some dense (non-conductive) foam plastic to fill the extra length, and stop the battery from rattling in the case. The internal dimensions of any suitable battery case, need to be at least 47.5 x 36.5 x 16 mm.

For working in harsh environments, sealed weather-proof cases are also available.

IDENTIFYING CHARGED / DISCHARGED BATTERIES
If spare batteries are kept in a pouch, or battery boxes, a simple method of distinguishing between charged and discharged batteries, is by inserting the batteries with the contacts facing either inwards or outwards, to signify charged or discharged. Alternately, if you use many batteries, you can have two battery pouches, one for charged batteries, and the other for discharged batteries.

LI-ION FIRE HAZARD
If a Li-ion battery develops an internal short-circuit, this can be the prelude to a thermal-runaway event that eventually causes the battery to rupture or vent, and spontaneously ignite. Other triggers for catastrophic battery events include: faulty charging, accidental short circuit by contact with metal objects, use of the camera or batteries outside of allowable limits, and heavy trauma to the camera. The fuel for the ignition is the electrolyte content of the battery, rather than lithium metal. Although lithium metal reacts violently with water, lithium-ion batteries, contain very little metallic lithium. As a consequence of the sparse metallic lithium content, water is a suitable and recommended extinguisher for burning Li-ion batteries, such as the NP-W126 types. There are two goals in extinguishing a Li-ion battery fire: First, to extinguish the initial fire, and second, to cool the immediate surroundings to avoid the ignition of other Li-ion cells. It should be remembered that a single NP-W126 type battery contains two Li-ion cells, so the X-T3 camera and grip (3 batteries in total) holds 6 cells, and each one will ignite in series (with a delay of between several seconds up to several minutes between each ignition), if the local temperature is not significantly lowered. Water is the best medium for lowering the temperature. However, covering the extinguished batteries, even with ice cubes, is not recommended, because it tends to form an air pocket which traps and retains the heat, leading to re-ignition.

Section - F

POWER MANAGEMENT SETTINGS

Mirrorless cameras, such as the X-T3, are inherently more voracious for power than DSLR's. The specific difference in power requirements is the mirrorless camera's use of an electronic viewfinder (EVF), or continuous use of the LCD monitor. The key to getting power consumption that approaches that of the DSLR, is to configure the EVF and LCD monitoring system, so that they are not turned on more than they need to be.

VIEW MODE SETTING
The most power efficient View mode option is "EVF ONLY + Eye Sensor", because it results in the viewing system being on for the least possible time. "Putting your eye to the viewfinder turns the viewfinder on; taking it away turns the viewfinder off. The LCD monitor remains off". The view modes can be cycled through by pressing the view mode button on the right side of the EVF housing.

AUTO POWER OFF SETTING
Try to set the Auto Power Off function to the shortest interval that you can comfortably work with. Wake-up from automatic power-off is achieved in less than one second by simply half-pressing the shutter button.

POWER MANAGEMENT MENU
Auto Power Off and Performance settings are accessed through the Power Management sub menu of the Camera's Set-Up menu. For convenience, the Performance (Boost) setting can be assigned to one of the function buttons. However, this is not necessary when the optional grip is used.

When the grip is attached, the "Performance" menu option, is greyed out, and unavailable, (to avoid selection conflicts) because the grip has its own dedicated performance (normal or boost) switch.

BOOST MODE
Unlike the X-T2 and X-H1 cameras, the X-T3 is able to realise top performance even without the optional battery grip. The high performance mode is called boost mode. When the highest performance is not needed, the camera can be set to Normal mode. In Normal mode, to conserve battery power, after ten seconds of inactivity (no button, dial, or touchscreen activation), the displays revert to a stand-by mode (low brightness, and very slow frame refresh rate). The display leaves this stand-by mode if there is a control activation event, or if the power mode is switched to Boost. There are no menu options for modifying this behaviour. However, if you are not using functions that that take a high power drain (continuous auto-focus, continuous high-rate stills shooting, and high resolution video), then leaving the camera in Boost mode should not produce any significant run time deficit.

According to the advisory message displayed when non-S type batteries are loaded, "Boost mode function is restricted". The exact restrictions, for this situation, are still being compiled. (I will update this guide, as further information becomes available).

Section - G

EXTERNAL CHARGERS

BC-W126S / BC-W126
The release of the X-T3 was accompanied by the introduction of a new battery charger. The newer BC-W126S is the charger generally supplied with the X-T3 camera, although, the Owner's Manual (page xix) states: "A BC-W126 battery charger may be supplied in place of the BC-W126S in some countries or regions". The two chargers are interchangeable, and either charger can be used for either battery (NP-W126 or NP-W126S).

The two chargers differ in two main points: The method of connecting to the mains supply, and the slightly increased maximum output current by the BC-W126S. (Does the newer charger differentiate between the older NP-W126 and the newer NP-W126S batteries, when charging them? I don 't know yet, but keep in mind that the two battery types have a different resistance level on their [S] contacts, so the charger may differentiate, and charge them slightly differently. But, that's pure speculation. I will try and test this when I make a break-out box for the charger.)

NON-OEM CHARGERS
Some non-OEM chargers can deliver functionality and flexibility not available from the standard supplied charger. Beyond cost, you should consider how the charger fits in with your workflow and approach to photography. It is also important to remember that the quality of the charger can have a significant effect on short-term and long-term battery performance and service.

UNEXPECTED INTERACTIONS
Power banks utilise a voltage converter circuit to change the battery voltage to the required USB supply voltage. Power is lost due to the conversion process, so it is typical for power banks to turn off the conversion circuit, if the power bank senses that the connected device no longer requires power. (The power bank will assume this if current draw falls below a certain threshold). At the same time, some chargers (typically, "smart" chargers), may momentarily suspend charging at regular intervals, in order to take measurements of the battery's state of charge. If the power bank's checking of the current flow, and the charger's checking of the charge state happen to coincide, the power bank may momentarily shut down. After the smart charger's state of charge check, the power bank will sense the charger's need for power, and power up again. This gives the unexpected behaviour that the pair of devices "power off" momentarily, and then resume operation. The momentary power interruption does not affect the charging of the batteries, but it does have the effect of causing the charger's count of accumulated milli-Amp hours (mAh) to reset back to zero, each time a power interruption occurs. I have experienced such an effect when powering the Nitecore FX1 with some power banks (including Tomo). However, if you place a USB power monitor in-line between the power bank and the charger, it can sometimes act as a buffer, so that power interruptions tend not to occur, and the effect of the mAh count resetting is avoided.

OVER-TERMERATURE PROTECTION
One very important factor, when considering non-OEM chargers, should be, whether the charger implements any kind of temperature monitoring, while charging. This will mean, either the ability to monitor the NP-W126S or NP-W126 battery's thermistor (on the battery's [T] contact), or the charger having its own built-in temperature sensor. Over-heating the batteries while charging will produce cumulative damage to the batteries (noticeable as as a decline in the battery's performance, or as swelling, or venting of electrolyte reduction gases). Two third-party battery chargers that are known to implement battery temperature management are, the JJC DCH-NPW126 dual slot USB charger, and the Watson Duo Charger, dual slot AC charger (both chargers utilising in-charger battery temperature sensors). The Nitecore FX1 dual slot USB charger (utilising a third battery contact to monitor the battery's thermistor output), reports the internal temperature of the genuine Fujifilm batteries (not of non-OEM batteries, however), and it should be noted that it does not terminate charging if the temperature exceeds the allowable temperature range - the user must do that.

Note that if the battery is non-OEM, and does not implement a working thermistor, then a charger's thermistor monitoring function will be ineffective, since there is no genuine temperature information to monitor (only the battery's fixed 10kΩ output by the [T] contact, which flags a "within acceptable temperature range" status, required by the Fuji charger before it will initiate charging).

Section - H

X-T3 USB PORT

The X-T3 camera has a USB type-C (USB 3.1 Gen 1) connection port. As well as its data transfer function, the port can also be used to input 5 Volt power for charging the battery in the camera body, or to assist powering the camera's operation.

MODE SELECTION
Because the X-T3 has tethered shooting functionality, connection of a USB cable can trigger unexpected camera behaviour, if the Set Up Menu's "PC Connection Mode" setting is not appropriate. How the 5 Volt supply is utilised depends on camera mode (off, shooting, or playback), as well as the PC Connection Mode menu settings. If not tethering to a computer, a relatively trouble-free setting is "USB Card Reader" mode.

CONNECTOR TYPES
The USB socket accepts a USB type-C plug. However, depending on the type of device used for charging, the cable could be either a USB type-C to type-C, or a USB type-A to type-C cable.

According to USB standards, the X-T3 is considered a high power device, since it requires at least 500mA from the USB supply.

Since all of the USB standards from 2.0 onward can deliver at least 500mA (composed of an allowed maximum of 5 x 100mA load units, as defined under the USB standard), most USB compliant outputs meet the X-T3's charge requirements. It is best to use the highest current-capability port for powering or charging. If the device manufacturer has implemented port colours, they can be a convenient method of differentiating between the power capabilities of different type-A port options, on a desktop or notebook PC. Port colours are not mandatory, however, members of the USB Implementors Forum (USB-IF), tend to assign the colours consistently. Of course, if the power output port is a type-C port, you can assume that it is USB 3.1 standard.

If you have previously been working with USB 2.0 and 3.0 charging methods, and using type-A and micro-B connectors, the X-T3's adoption of the type-C connector does not mean that your previous charging system needs to be replaced. As long as the system terminates in a type-C connector, for connection to the X-T3, you can continue as before.

It should only be necessary to acquire a new type-A to type-C cable, or even a micro-B to type-C adapter, if a charger has a fixed cable ("hard-wired captured cable"). These plug adapters can also be used on legacy cables (earlier generations than type-C). The converse scenario might occur if you have acquired a USB power supply with fixed type-C cable, and you want to charge a power bank, or use a USB battery charger, that only has a Micro-B input port. In this case, a type-C to Micro-B adapter with the genders reversed can be used to make the connection for charging.

Please be very careful. These adapters are very small, and therefore dangerous to leave within reach of infants and small children, who might put them in their mouth, with the risk of choking.

It should be noted that the USB type-C standard implements two Control Channel pins (CC1 and CC2) on the type-C connector, and these are used to establish and manage the Source-to-Sink connection. Since legacy cables and connectors do not implement these Control Channel lines, attaching type-C adapters to a legacy cable will not convert it to a "full featured" type-C compliant cable. However, it can still produce a functional USB power transfer cable.

USB "POWER DELIVERY"
What happens if the X-T3 is connected to the USB PD (Power Delivery) port of a computer, power bank, or to a USB PD power supply? We know from experience that if the X-T3 is connected to a USB PD power supply with a hard-wired captured cable (so that there is no doubt that the cable is PD aware, compliant, and capable of conducting high currents), the X-T3 will draw 5 Volts at up to 1500mA for charging, or operation in video mode. In stills photography operation, the current draw is considerably less. In contrast to this, when the same USB PD power supply, is used to charge a 20000mAh PD power bank, the power bank draws 9 Volts at 2000mA.

Because the X-T3 has a Type-C port (which people often associate with PD), and because Fujifilm has recommended external USB power via the Anker PowerCore powerbanks (which support PD), there might seem to be the implication that the X-T3 supports elevated power levels via the PD functionality. However, as far as I am able to establish, the X-T3 does not require or negotiate elevated PD power levels (that is, power above the PD default), although it is compatible with USB systems that do support PD. So, if a charger, power bank, or PC conforms with the general USB specifications, it can be used to supply USB power to the X-T3, whether the device supplying the power supports PD or not. The following (printed in red) is simply to explain how PD works, and why we can say that the X-T3 does not negotiate elevated power levels.

USB Power Delivery (PD) is designed to co-exist with standard USB Battery Charging implementations. The USB Power Delivery protocol requires the following steps: Connection, Default Operation, Discovery, Negotiation, and Contract Operation. When a USB host and device are first connected, the initial operating conditions are the USB Default Operation, which assumes a DFP (Downstream Facing Port) supplying vSafe5V (a voltage level of 5 Volts, which is safe for all USB devices) over the VBUS line, and a UFP (Upstream Facing Port) consuming power from the VBUS line. In the case of USB PD compliant equipment, once these default conditions are set, a Discovery process can begin, if the connecting cable meets requirements. Discovery comprises the exchange of structured VDMs (Vendor Defined Messages) resulting in identification of the Port Partner, its supported SVIDs (Standard / Vendor IDs) and Modes. After the Discovery process, power Negotiation begins. The Source (power supplier) advertises its capabilities, and the Sink (device which will consume the power) requests one of the advertised capabilities. Then, the Source acknowledges the request and alters its output to satisfy the request. The result of this process is a Contract for power delivery/consumption between the two port partners. The contract specifies both power level and direction between the Port Pair. Typically, the contract continues until the ports are disconnected.

Cable specifications are an important part of the USB PD protocol, because, as well as the power source being able to supply the required power, a connected cable must also be able to carry that supplied power. Higher power requires a higher specification cable, for instance, heavier gauge conductors. Standard Type-C cables (with no built in circuitry) should support up to 3 Amps of current by default. But in order for a USB PD compliant source to advertise capabilities greater than 3A, the Type-C cable must be an Electronically Marked Cable Assembly (EMCA). The electronic marking is accomplished by embedding a USB PD controller chip into the plug at one or both ends of the cable. The cable controller stores configuration data related to the identity and capabilities of the cable. Electronic marking is needed in a Type-C Cable when VBUS current of more than 3 Amps is required. Of course, an Electronically Marked cable will be more expensive than the corresponding un-marked cable. The benefits of an Electronically Marked cable are not relevant for the X-T3 camera, since it does not require current at higher levels than the 3A default. The next step up in current rating is 5A, and since 5 Amps at 5 Volts is 25 Watts, that already exceeds the X-T3's 18 Watt power rating. The simple "un-marked" type-C cables are sufficient for the X-T3's power requirements. Importantly, after the setting of the USB Default Operation, if the PD protocol cannot be established, then the power remains at the default vSafe5V , which should mean there is no risk of damage to equipment. In this way, interoperability between PD capable equipment and legacy USB equipment and cables, is maintained.

In practical terms, the significance of USB PD for the X-T3 camera seems to be the ability for the camera to draw 1500mA at 5V (even with just a standard type-C cable), compared to the typical 900mA at 5V from the USB 3.0 / 3.1 bus. This increase in current represents a modest improvement. Note however, the USB 3.0 Dedicated Charging Port (DCP), could already deliver 1500mA. Although the USB PD standard allows, in principle, power delivery up to 100 Watts, the X-T3's ability to consume power is limited, by its highest battery-safe C-rate while charging, and in operation, by its maximum working temperatures, since more power produces more heat. Increased heat, without a corresponding ability to dissipate heat at a higher rate, would be a typical precursor to camera lock-up events. Remember that the X-T3 is rated at 18 Watts. So, even with USB PD, do not expect the X-T3 to be able to benefit from more than 5 Volts at 3 Amps, maximum (15 Watts).

In summary, it would seem that the X-T3, even in a fully PD compliant connection context, does not exploit the possibility of negotiating elevated power levels through the PD protocol, probably because the camera does not need those elevated levels.

The camera is, however, able to gainfully utilise the increased default power level offered by PD capable equipment (maximum current of 3000mA, rather than 900mA), and this is why connection to a PD capable port (marked with the letters "PD"), is both advantageous, and preferable to connection through a standard port. If your goal is to get maximum and continuous power for video production, an alternative option is to use V-Mount batteries with D-Tap (as explained in Section J - "DC Coupler").

USB HUBS NOT SUITABLE
The Owner's Manual (p. 33) states: "Connect the camera directly to the computer; do not use a USB hub or keyboard." Typical USB bus powered hubs cannot be used since, although they draw five load units (100mA each USB 1.0/2.0, or 150mA each USB 3.0), 1 unit is used by the hub controller, and the remaining 4 units are distributed among the hub ports (1 unit each for a 4 port hub). The available current from a hub port could be as little as 100mA, and probably not higher than 200mA, which is not sufficient for the X-T3's charging requirements. This limitation on current supply from hubs may not translate to USB PD hubs, since the current supplied at each hub port can be negotiated. We await further testing of USB hubs.

INTERNAL CHARGING
Power delivered via the USB port will charge the body battery, when the camera is switched off, however, it does not charge the grip batteries. Using the USB port, the time to fully charge a flat battery is about 300 minutes, or 5 hours, when connected to a standard USB port. This time is reduced to about 2 hours when using a PD supply port. Ability to charge the body battery via USB means that the battery can be left in the body on a quasi-permanent basis, which makes it un-necessary to remove the grip in order to charge the body battery (an inconvenience of the X-T1 camera when used with grip).

EXTERNAL POWERING
When the camera is switched on, power input via the USB port, is used to supplement the power available from the battery. Importantly, the camera cannot be operated independently (that is, without a battery installed) solely on power delivered via the USB port. Even if the USB 5 Volts is delivered at a 1.5 Amps of current, that only produces 7.5 Watts of power, which is well below the X-T3's 18 Watt power rating. However, during operation with the body battery installed, the USB supplied power can supplement the battery power, so that the battery does not run down, or is discharged only slowly.

When connecting the X-T3 for powering via the USB port, not only the USB connection settings (set via the Menu system), but also the type of cable (standard cable, charge-only cable, OTG cable, etc), as well as the equipment being connected to, determine how the X-T3 behaves. Often, the user may not be certain about the exact technical specifications of the cable they are using, or the generation and capabilities of the connected equipment. If the X-T3 senses that it is connected for data transfer, it may go into USB transfer mode (black screen, with the USB symbol in upper left corner) when it is turned on, and shooting under external power may not be possible, while the USB is connected.

In such a case, try turning the camera on before connecting the USB power supply. (In general, the USB specification supports "hot-swapping", that is, connecting or disconnecting the USB port while the device is turned on). If this does not solve the issue, you may have to explore other USB host or cable options (such as using a charge-only cable), to enable shooting with externally supplemented power.

Since firmware update version 2.00, there is a power supply icon available to indicate external power. However, the icon indicates utilisation rather than physical connection.

So, if the grip is attached, and it holds charged batteries, the icon will not initially be shown, despite USB power being connected. This is because the camera will preferentially draw power from the grip batteries. (Two charged grip batteries are able to deliver more power than the USB).

When both of the grip batteries are depleted, then the camera will start to draw USB power to supplement the body battery, and the power supply icon will show.

USB POWER SOURCES
The USB power can be delivered to the camera from a computer, an AC to USB adapter, a USB power bank, or an automobile USB outlet or adapter, etc. However, DO NOT use any unregulated voltage supply at the USB port. The maximum allowable voltage of the USB standards is 5.25 Volts (5.0 Volts +5%), and this should be considered the maximum voltage allowable at the X-T3's USB port. While the nominal USB voltage is 5 Volts, the allowed minimum is 4.75 Volts, although a device powered by the USB bus is expected to be able to operate with voltages down to about 4 Volts.

FUJIFILM AC-5VF POWER ADAPTER
This small power adapter with integrated power plug, delivers 5 Volt USB power, up to 1.0 Amp, via a USB-A socket.

The USB port offers many possibilities of internal charging, and externally supplemented power for both fixed location, and mobile setups, using a wide range of USB power options.

SECTION - I

POWER BANKS

A power bank is an external battery pack that can deliver power for charging or operation of mobile electronic devices, including digital cameras. The power bank's input and output are usually (but not always) via USB ports.

ADVANTAGES
Power banks allow portability and versatility. One big advantage is that the power they hold can be assigned to devices in an ad hoc manner (for example, to charge the camera, a smartphone, a tablet, etc, as needed). A second advantage is the ability to recharge batteries on-location, if and as necessary. Although it could be argued that there is a time and weight advantage in carrying pre-charged NP-W126S batteries, rather than a power bank and USB charger, the price difference between several genuine batteries, and a power bank, may be the critical deciding factor.

For high capacity power banks, the biggest advantage may be in powering the X-T3, in order to achieve extended running times. Note that, for the X-T3 camera, the power bank does not need to support the USB PD (Power Delivery) function, although having PD would be preferable. In general, a power bank without PD function, may be sufficient for stills photography, but for extended duration video usage, a high capacity PD power bank would be more suitable.

BRANDED POWER BANKS
It is recommended only to purchase branded (traceable registered brands) power banks, with good long term usage reviews. Unbranded power banks may state exaggerated capacities, have sub-standard internal assembly, and use un-matched cells (not matched for internal resistance) which will ultimately lead to reduced performance or even unit failure, depending on how the internal cells are connected (series, parallel, or combination).

PORT CAPABILITIES
Input ports (for charging the power bank) are typically Micro B type, or USB type-C. USB type-C ports, if PD capable, are bi-directional (marked "IN/OUT"). Not all type-C ports are PD capable. Sometimes, the type-C port is provided, simply to enable use of more recent power adapters, which may have a type-C cable. Output ports (for drawing power from the power bank) are typically USB-A, or type-C.

Since the USB Consortium maintains compatibility between different generations of USB standard, either type can be used, as long as the correct cable is available.

In the context of the X-T3 camera, USB-A ports which are designated as Quick Charge 2.0/3.0 ports, do not offer any advantage over standard USB-A ports, since the X-T3 does not recognise the QC protocols. However, the type-C ports which are designated USB PD, will allow the X-T3 to draw higher current (up to 1500mA, compared to up to 900mA drawn from a non-PD port). Power banks which offer lower capability ports (micro-B and USB-A) as well as higher capability ports (type-C PD) give an advantage of allowing the user to select charging and supply rates, by selection of the appropriate input or output ports (with the appropriate cable, of coures). Although fast charging is convenient (and sometimes necessary), lower rate charging is in the long term, beneficial to the longevity of the power bank.

EXPECTED OUTPUT CURRENT
Expect the X-T3 to draw up to 900mA of current from a power bank's standard type-A output port, regardless of the port's "marked" maximum output, which may be 1 Amp (1000mA), 2 Amps (2000mA), or even Quick Charge 3.0 (3000mA). If the power bank has a type-C "PD" (Power Delivery) output port, expect the X-T3 to draw up to 1500mA of current from that port. The nominal voltage will always be 5 Volts, regardless of the supply's scalable voltage capability. Because the X-T3 will not (based on experience) draw more than 1500mA at 5 Volts (7.5 Watts), a power bank with an 18 Watt power capability would be more than enough to supply the X-T3's power needs. There is definitely no need for a PD supply with higher power (Watts) output capability. Be careful not to confuse output current in milli-Amps (which affects power), with nominal capacity in milli-Amp-hours (which affects the running time that you get from the power bank).

When comparing the current supplied by the Type-A port and the Type-C PD port, any supply deficit (the shortfall in the Type-A port's supply) must be made up by the X-T3's internal battery. However, if the usage is non-continuous, and the camera is allowed to auto-power-off, the internal battery can recover some of that power through internal charging while in the "Off" state.

REMOVABLE BATTERY POWER BANKS
Power banks that allow the batteries to be removed (sometimes referred to as DIY power banks, because the device is delivered without batteries, which the user must supply), offer many advantages:

• You can use the highest quality batteries, (You get to choose).
• Batteries can be replaced when their performance starts to decline.
• Batteries can be "borrowed" for other purposes (LED torch, for example).
• Spare set/s of fully charged batteries can be taken, on long expeditions.

An important consideration for removable battery power banks, is whether the internal cells have their own individual channels for charging (as in the Tomo units), or if the cells are all on a single charge/discharge circuit. In power banks with individual channels, the cells do not have to be matched (for balancing), and can differ in brand, capacity, age, and even state of charge.

With such a power bank, it is possible to give the individual status of each cell. However, to maintain balance between the internal cells on power banks where cells are all on the same charging circuit, the cells must be matched (they should be the same brand and type, and even from the same batch - indicated by having exactly the same production code). Ideally, the cells should be matched to have the same internal resistance, but most users do not have the equipment needed to make this determination.

EXPECTED EFFICIENCY
Power banks normally contain an array of lithium-ion (or lithium-polymer) cells. The Panasonic NCR 18650B Lithium-Ion cells, are typical of the cell type used in many power banks. Due to economy-of-scale in their manufacture, eight of these would probably cost less than the price of one NP-W126S battery. (Although these 18650 cells would be typical of the cell type used in thicker bodied power banks, the ultra slim type power banks would usually use lithium-polymer "pouch cells", which are relatively flat). The NCR 18650B energy capacity (3340mAh nominal capacity x 3.6 Volts nominal voltage), is approximately 12 Watt-hours, per cell. (The new Sanyo 18650 GA cells are 3500mAh nominal capacity, so 12.6Wh of energy). In contrast, the energy capacity of the NP-W126S battery (minimum capacity of 1200mAh x 7.2V) is 8.7 Watt-hours. By converting the specifications to energy capacity in Watt-hours, it is easy to compare cells and batteries of different voltages.

A large power bank could contain perhaps eight of these 18650 cylindrical cells (or the equivalent in pouch cells). However, real electrical systems are never 100% efficient, and there are always losses, especially when voltage conversions take place. When supplying power from a USB power bank, there is an initial conversion from the 3.6 Volts of the power bank's internal cells, to the 5 Volt USB output, (and then a further conversion within the camera, from 5 Volts to the various internal voltages required by the X-T3). The 3.6 Volt to 5 Volt conversion causes a notable reduction in available energy, so, to achieve a more realistic estimate of the power advantage of the power bank supply, you can compensate the power bank's energy capacity by a percentage that allows for the 3.6V to 5V conversion losses. Since we don't know the actual loss values, you can assume 90% (or 85%) efficiency, and subtract 10% (or 15%) to allow for conversion losses. Then you can divide the remaining Watt-hours energy capacity by the 8.7 Watt-hours of the NP-W126S battery, to find the "number of batteries" equivalence of the USB power bank. So, in the case of a 20000mAh power bank (20Ah x 3.6V = 72 Wh), the finally available energy capacity (after a 10% reduction to allow for conversion losses), might be taken to be about 64.8Wh, which is about 7.4 times the NP-W126S's energy capacity.

Sealed (not designed to be opened by the user) power banks, usually don't specify what type of cells, or how many, are inside the power bank enclosure, but assuming that the stated milli-Amp-hour capacity is reliable, you can use a lithium-ion cell voltage of 3.6 Volts (or 3.7 Volts for lithium-polymer), in order to determine energy capacity in Watt-hours.

MULTI-VOLTAGE BANK VOLTAGES
Although most common power banks are designed to deliver power according to USB standards (normally 5V), it is also possible to get multi-voltage power banks. These may be of interest to the X-T3 user, since the grip can be connected to a 9 Volt power bank for charging and camera operation, and the body (without grip) can accept the DC coupler powered by a 9 Volt power bank, for operational power.

If supplying a nominal 9 Volts via the grip's DC socket, the low range tolerance is about −3%, so the voltage should not go below about 8.75 Volts; otherwise the display will flash the low power symbol (red battery with no bars), and the camera will auto power-off. However, this low range cut-off does not apply when supplying power via the CP-W126 DC coupler.

BICYCLE LIGHT BATTERY BOXES
These battery boxes are designed to power high performance lighting on push-bikes. Some of them provide both a 5 Volt USB output as well as a nominal 7.2 Volt (8.4 Volt maximum) 5.5mm male DC plug output which is suitable for connection to the X-T3 via the DC coupler (with a suitable conversion cable). Note that this voltage is not high enough for the vertical grip's DC input socket, however.

Two significant features of these battery boxes are, provision of strap lugs for secure mounting, and a high degree of weather sealing (since they are intended for mobile outdoor use).

These battery boxes usually take 18650 type cells. Ideally, each pair should be matched for internal resistance. The USB output is by a standard type-A connector.

POWER BANKS RECOMMENDED BY FUJIFILM
Fujifilm is currently recommending:

Anker PowerCore Speed 20000 PD, and
Anker PowerCore+ 26800 PD, power banks.

These have both USB-A and type-C ports. Whenever type-C PD ports are provided, they should be used in preference to the USB-A or type-C (non-PD) port, because the type-C PD port can potentially deliver more current. The PD port can deliver 5V at a maximum of 3000mA, (although the X-T3 only draws 1500mA), compared to 900mA from the USB-A port.

CAPACITY LIMITS FOR AIR TRANSPORT
For the purpose of implementing air transport safety regulations, lithium-ion (and lithium-polymer) batteries, are categorised according to their energy capacity in Watt-hours. In this context, a power bank is considered to be a "battery". The lowest and least restricted category is 100Wh or less. A power bank with over 100Wh of energy capacity would not be allowed to be carried on a passenger aircraft without the specific approval of the airline.

The energy capacity in Watt-hours can be found by multiplying the rated capacity by the nominal voltage of the internal cells. Assuming simple parallel connection, we can take 3.6V as the nominal voltage for lithium-ion cells, and 3.7V as the nominal voltage for lithium-polymer cells. If in doubt as to the type of cells, use 3.7 Volts. The 100Wh category limit explains why we see that very high capacity power banks seem to be limited to about 26800mAh (26.8Ah). The energy capacity of a 26800mAh power bank would be 26.8Ah x 3.7V = 99.2Wh, which is just inside the 100Wh limit of the least restricted category for air transport. Allowed units need to be taken as carry-on baggage, not checked-in baggage.

Section - J

DC COUPLER

The DC coupler is a common method used by camera manufacturers to provide a camera with an optional DC power socket. The DC coupler replaces the normal battery, and can provide a virtually continuous and unlimited supply of power.

ATTACHMENT
The cable exit-point is on the right-hand side of the battery chamber door. When the door is open, and the battery removed, you can use a finger-nail to pull up the rubber seal. The seal is anchored, so that it doesn't fully come away from the body.

After inserting the DC coupler, with the cable on the exit-point side, ensure that the cable feeds properly through the exit route, and close the battery chamber door. The camera can now be powered via the DC socket which terminates the DC coupler's cable. Remember to set the power Auto-Off setting to "off" to prevent the camera turning off automatically.

9 VOLT SUPPLY
The Fujifilm CP-W126 DC coupler combines with the AC-9VS power adapter to power the X-T3. A further possibility is to use the coupler to connect another appropriate (9 Volt) power source, for field usage. Because the maximum voltage of the NP-W126S battery is 8.4 Volts, an input voltage higher than 8.4 Volts, alerts the camera that power is being input via the CP-W126 DC coupler, and the "external power" symbol will be displayed instead of a battery level display. The rating for the power supply to the DC coupler is 9 Volts at 2 Amps (therefore, 18 Watt), and these specifications should guide the choice of power source. One possibility is a multi-voltage power bank which includes a 9 Volt output. The USB booster cable (described in section D), can also be used, to power the body via the CP-W126, from a 5 Volt USB power bank. However, this will only be able to deliver about 1 Amp of current, and so, would not be suitable for operation at the very highest performance levels, since there will be no internal battery to supplement the DC coupler's supply.

D-TAP
The V-Mount battery system is a portable external power system widely used in professional video and cine production. (An alternative system is the Gold-Mount system, to which the following information also applies). The system allows very high capacity battery packs to be attached to a battery plate, which can itself be mounted to a video camera rig, a tripod, or a light stand, etc. As well as standard co-axial DC power output sockets (most commonly, 12 Volt), the system also allows access to power via D-Tap plugs, that fit into sockets which can be on the battery pack, or the mounting plate.

The standard voltage of the V-Mount and D-Tap system (14.4 Volts nominal, and 16.8 Volts maximum) is too high for the X-T3's maximum of 9 Volts, however, a special voltage reduction cable can deliver the correct voltage to power the X-T3. Never connect a D-Tap output directly to the X-T3 without a suitable voltage converter.

A D-Tap to X-T3 connection will consist of three main parts: a cable with male D-Tap access plug, an in-line voltage converter to reduce from 24 Volts (maximum) down to 9 Volts, and a CP-W126 DC coupler.

These may be available as separate units, or one single cable with D-Tap, converter, and DC coupler.

The benefits of utilising the V-Mount and D-Tap system are, very high power storage capacity, the ability to power multiple devices (camera, external monitor, external HDMI recorder, video light, etc) from a single power source, built-in charge and charge monitor functions, as well as utilising the V-Mount plate and battery to counter-balance the front-heavy load of the camera in a video rig.

DC COUPLER APPLICATION
• Camera operation over long periods of time
• Static operations where the camera remains in a fixed position
• Situations where an interruption of operation must be avoided
• Situations where camera operation is be left unattended / un-monitored
• In situations where camera over-heating is an issue (for example, continuous 4K recording), removal of battery from the body can reduce number of contributors to internal camera heating

APPLICATION EXAMPLES
• Time-lapse photography extending over many hours or even days.
• Large volume copying (for example, books or documents) where the camera is mounted in a fixed copying rig.
• Surveillance photography, or wildlife photography, with automated triggering, such as a sound activated trigger, or laser trigger.

CLOCK RESET
When DC coupler is used, since there is no battery in the camera body, if DC power is turned off for an extended period of time, the camera clock will be reset. However, the camera should be able to keep its internal clock battery sufficiently charged if external power is connected at least every couple of days.

SAFETY ISSUES
Due to the camera being tethered by a power cable, various safety issues must be considered, as a matter of priority. Possible hazards include those generic to the use of AC voltages, trip hazards from cords/cables, and possible topple-and-strike hazards from cable pulling against tripods.

NOT APPLICABLE WITH GRIP
Please note that the DC coupler cannot be used in the X-T3 concurrently with the grip, because when the grip is attached, there is no exit point for the coupler's cable. However, the DC socket of the grip makes use of a DC coupler redundant anyway.

Section - K

ALTERNATIVE POWER SUPPLIES

Alternative power supplies open the opportunity to use the X-T3 remotely from mains power for extended periods of time.

AUTOMOTIVE POWER
Access to a motor vehicle allows the use of a 12 Volt to USB converter, or even the USB power socket built in to the dash of late model cars. The output should be at least 1.0 Amp, but preferably more.

Although it is common for recent vehicles to have USB outputs as standard, many of them are limited to 1 Amp of current, so you may wish to use a plug-in converter, in order to access higher current.

BUCK CONVERTERS
A buck converter is a voltage step-down device. The example shown (Deek-Robot DK-D20252 Mini DC Power Supply) provides two regulated outputs: 5V, 2A (USB), and 1-20V, 2A, from a 8-20V, 2A input.

Such a device may be useful in situations where you want to use a range of different power inputs (12V AC converter, and 12V car "lighter" outlet), or where different voltage outputs are required for a range of devices requiring different power or charging voltages. in such situations, it can reduce the number of power and charging devices that need to be carried.

Several important warnings, when using this type of buck converter: The input voltage must always be higher than the output voltage (otherwise you can burn-out the converter). Make sure that the input current is sufficient to supply the output currents. And finally, be aware that if the buck converter fails, there is the possibility of the full input voltage being delivered at the output; so make sure that the need to use the converter is weighed up against this risk.

HOW TO USE SOLAR POWER
Small portable solar panels allow the opportunistic recharging of power banks, which can then supply the camera, as well as other remote location gear. Don 't ever connect the solar panels directly to the camera. Instead, use the solar panel to charge a power bank, and then later, you can use the power bank to charge the camera batteries (internally or externally). Many portable solar power-supplies, although they deliver power via a USB socket, have an output that is unstable and subject to interruption. The voltage can exceed the allowable USB voltage by several Volts (especially if the Sunlight is very intense), if not connected to a high-enough load to bring about the appropriate voltage drop. A removable battery power bank with high capacity batteries, should place enough load on the supply, that the voltage drops to within the proper range for charging the power bank. At any rate, a catastrophic over-voltage event damaging the power bank, or its batteries, is a small cost compared to the possibility of damaging the camera. Use an inline USB power meter, so that you can be sure of what voltages are being delivered.

A folding unit, like the one shown, can give some degree of power control in ultra-bright conditions, by not being fully opened. Fully opened in decent Sun, it can easily produce 5 Watts of power. At midday in the middle of Summer, at mid latitudes, and properly aimed, it can produce several Watts more.

Since high temperatures are not good for Li-ion batteries, the power bank or charger will need to be kept in the shade while charging, if the ambient temperature is very warm. You can use a radiant barrier material (such as metalised mylar bubble sheet) to form a shade cone for this. The conical shape is used because it is easy to form, tends to be self-supporting and resists collapsing in on itself. The weight of the power bank or charger, placed within it, stops the cone from opening out.

However, in very cold climates, the battery might benefit from being warmed up by exposure to the sunlight. A battery temperature in the 20's of degrees Celsius, would be nice for the batteries.

If the Sunlight is not optimal, and if you have a removable battery power bank, rather than trying to charge the power bank, it may be more efficient to charge a single 18650 battery in a USB battery charger, and this battery can be swapped into the power bank when needed.

The solar charging system should not be set up near dried vegetation, due to fire risk. At times of extreme fire danger, it should not be left unattended at all. If you are on the move, and the Sun is at your back, you can do some charging opportunistically, by attaching the solar panels to your backpack.

Section - L

USB POWER METERS

One of the most useful devices for power management is the in-line USB power monitor. This device can display instantaneous voltage, current, and power throughput, as well as accumulated or drained milliAmp-hours, etc. Some also allow time, voltage, and current limits to be set. This device is very useful for charging situations where either the charger or the storage device (such as power bank) does not have a detailed status display. USB power meters are available with either USB type-A or USB type-C connectors.

The displayed readings will reflect some discrepancies from losses due to the power monitor's own processing and display and illumination, however the readings should be sufficiently accurate for our intended purposes.

VOLTAGE / CURRENT MONITORING
Although the camera's LED indicator shows charging in progress or charging completed, the camera needs to be switched on in order to get a more detailed indication of current SoC, and charging progress.

If a power monitor is inserted inline, it can continuously show the instantaneous supply current. The following chart gives approximate values, and does not account for conversion or other incidental losses.

When using the USB port to charge the body battery, and using an inline USB tester, the present status of the supply current is a useful indicator of the position in the charging process.

Because the actual charging current can vary according to battery condition (SoH), as well as environmental conditions such as temperature, the quoted values are mainly intended as a conceptual illustration of the significance of variations in current flow during the charge process.

Section - M

DISCLAIMER

Incorrect or inappropriate use of the X-T3's power systems, could lead to damage or even destruction of the battery, camera, or other ancillary devices. Furthermore, catastrophic failure of the lithium-ion battery could lead to serious personal injury.

Before acting upon any information in this guide, the camera user should satisfy himself / herself that they are acting with due diligence.

This guide is a compilation of information that I collected for my own use of the X-T3 camera. I am making it available in the hope that some of the sometimes difficult to obtain information, may be of use to others. However I cannot guarantee the accuracy of all of the information given here. There is the possibility that some of this information may not be correct, despite my own good intentions and diligence. You, as the camera user, must verify this information for yourself, and decide whether acting upon it, is prudent and safe. I cannot be held responsible for any damage of injury.

Directives about powering the X-T3 are given in the Owners Manual. These directives include instructions not to use non-Fujifilm batteries and non-Fujifilm chargers. Usage that fails to follow these instructions, could have the consequence of voiding your warranty.

[ Last updated: 15 November 2019 ]

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NP-W126S Counterfeits

A Visual Guide to Spotting the Fakes

The NP-W126S is the current version of the battery used by Fujifilm X interchangeable lens cameras (X-A, E, H, M, Pro, and T series). Because the NP-W126S is a premium battery which sells at a premium price, fraudsters re-badge and repackage inferior batteries, to pass them off as genuine Fujifilm batteries, in a money making scam. This guide is specifically about counterfeits, meaning that the batteries (without authorisation) carry a copy of the Fujifilm brand logo, and are designed to resemble the original product so closely as to be virtually identical to it. They are designed for the purpose of deceit.

I will present practical tests which can be used to determine whether a battery claimed to be a genuine "Fujifilm NP-W126S" is legitimate, or counterfeit. The distinctions made in this guide, reflect the situation at the time of writing. However, Fujifilm, (or the battery's manufacturer, Panasonic) could at any time, make changes to the battery, which might supersede this information: - "Specifications subject to change without notice", as they say. Because of this, it is best to frame the results of your individual tests in terms of "normal or suspect", rather than jumping immediately to a "real or fake" conclusion. Every occurrence of a "suspect" finding, contributes to the accumulating evidence that the battery may not be genuine. When the bulk of the suspicious evidence becomes compelling, then you can declare the battery a fake.

Many of the analyses shown here, can be made without the need of any instruments. If you are familiar with what to look for, you can positively identify a fake (even a very good copy), in about 2 to 3 seconds. To determine the authenticity of a particular battery claiming to be a genuine NP-W126S, look at:

[ 1 ] ORIGINAL PACKAGING

When purchased as an accessory, the original packaging of the NP-W126S battery includes the box, instructions and a plastic storage pouch for the battery.

The box and instructions are specific to the battery type (that is, they don't use a generic box and instructions sheet that suit various models of lithium-ion battery).

Some counterfeiting is very un-sophisticated: In the following phoney box, based on packaging from the past, the battery diagram shows the wrong battery (they sometimes place a barcode label over this, to obscure it).

Other discrepancies are the lack of Japanese text, and the old style Fujifilm brand with the small "Fuji" symbol, which has not been used since 2006.

That logo is an anachronism for the NP-W126S battery, which was released ten years after the change to the present Fujifilm brand logo (with the distinctive font, and the "cutting-edge" design feature on letters I and F).

[ 2 ] PRINTING ON THE BATTERY

The battery is printed on two faces, and one end (the circular orientation patch). When examining the details of the printing on the battery in question, we can look at:

TEXT & GRAPHICS LAYOUT & CONTENT
These are the current printed faces of the NP-W126S battery. As far as I can find out, there is one design for all markets. The logos of the various certifying agencies indicate a global coverage. The Fujifilm branding, battery type, and power specifications are found on the front face of the battery.

On the reverse face, can be found the contact pin-outs, safety warnings, and country of manufacture. Please note that the "JAPAN ONLY" words on the reverse side, refer to the Recycling symbol, rather than to a distribution market.

The above photographs detail the textual content of the genuine batteries. In contrast, one recent counterfeit version, mis-spells the name "Panasonic", on its front face, as "Panssonic", and on the reverse face, it gives the warning "CAUTION: Risk of Fire and Bums", instead of "Burns". Because the Fujifilm brand logo incorporates unique characteristics, such as the "cutting-edge" device on the central I and F letters, it can represent a challenge for the counterfeiter. This is the genuine form:

The counterfeiter's rendering might look OK without close inspection, but if you examine it with some magnification, you might find many anomalies:

THE INKS
The white print ink of the genuine batteries, is not an "intense" white, but could be described as a pale silvery-grey off-white. Likewise, the orange ink of the genuine batteries, tends not to be a "vibrant" orange.

In recent years, all NP-W126 class batteries have an orange coloured orientation patch on the end that faces out from the camera's battery chamber. The later series NP-W126 batteries had a square orange patch, while the NP-W126S has a circular patch.

The colour is a "burnt" orange, and is not like a "high-visibility" orange.

SCALE, BOUNDARIES & MARGINS
If you have a known genuine battery, you can compare the scale of the printed area, and the dimensions of the text and symbols boundaries. Even if precise measurements of the print boundaries cannot be done, it is often possible to visually notice discrepancies to the margins.

On the front and reverse faces, the area for printing is very slightly raised (by about the thickness of a regular sheet of paper on each face). Under good light, you can easily see the edges of this raised zone. With the genuine batteries, the upper and lower boundaries for the printing go almost to the edge of this raised surface.

On the non-genuine batteries, there may be a noticeable space between the upper and lower boundaries of the printing and the edge of the raised surface.

LAYOUT
Pay attention to the spacing between text and graphics. On one of the counterfeits, the electrical contact symbols are slightly smaller, and spaced further from the adjacent text.

Tiny layout errors can also be detected on minute examination of the text. For example, on the genuine battery's front face (with the Fujifilm logo), the tail of the Y in the word battery, lines up with the centre line of the number 6 below it:

In contrast, on one fake version, the tail of the Y lines up with just over the leading edge of the number 6:

If you have a known genuine battery to compare against, you may be able to find many printing discrepancies on the suspect battery. On this genuine battery, notice the name of the city Wuxi, is enclosed in brackets, with spaces on either side of them.

On one counterfeit battery, the spaces are missing:

SUMMARY EXAMPLE
The following gives an example of a currently available counterfeit battery. For comparison, the first photograph shows the front face of a genuine battery. The points for examination are circumscribed.

Now compare the suspect battery. Easily seen anomalies are: An inaccurate copy of Fujifilm logo (especially the "hook" of the letter J), a missing space before "NP-W126S", a dash that is too long in "NP-W126S", a stroke missing in the ム (mu) katakana script, and spaces missing either side of "(Wuxi)". There are actually many more inaccuracies, but these five are the most easily seen. Finally, of course, recall that the genuine battery is supplied with a soft storage pouch, not a hard cap.

A recent variation of this fake has "LITHIUM ION BATTERY" as a single word (with no spaces between words).

Note, also, that the "U" of FUJIFILM, is very rounded at the bottom, and of uniform thickness, in comparison to the genuine Fujifilm logo.

[ 3 ] OUTER CASE DESIGN

When a battery production facility produces tooling for the battery case, that tooling, and the production methods used, will leave characteristic signs that point to that plant or factory. No matter how good the printing is, these signs easily distinguish batteries from different manufacturers.

ANTI-REVERSAL NOTCH
On the electrical contacts end of the battery, there is a notched corner, which prevents the battery being fully inserted into the camera's battery chamber, if the battery is wrongly oriented, either end-wise or face-wise.

You can check the shape of this notch, as an indication of authenticity.

RETAINING NOTCH
This notch is for securing the battery in the BC-W126S (or BC-W126) charger, and also the battery trays of the vertical grips. The charger has a pawl which latches into this notch, so that the battery is held securely while charging.

At certain angles, the notch of the genuine battery appears to be "black". Also, check whether the corners of the notch are "square" (which they should be), or "rounded".

GATE-MARKS
Gate-marks (or, gate-scars) are remnants of the injection molding process that produced the battery's plastic case. They are tiny spots, about a millimetre in diameter.

The genuine Fujifilm battery has eight gate marks (four on one side, and four on the other side), and the positions do not vary.

Non-genuine batteries may have no visible gate-marks, or if they do have gate marks, they may be in different places, and a different number. Currently, observation of gate-marks is one of the most reliable discriminators between genuine and non-genuine batteries.

[ 4 ] ELECTRICAL CONTACTS

Under good light, the electrical contacts of the NP-W126S batteries, look quite different from those on many non-genuine batteries.

The colour should not be a "Hot" gold.

[ 5 ] SURFACE TOPOGRAPHY

On genuine NP-W126S and NP-W126 batteries, the printed faces have a slight concavity to them. They are not perfectly flat. The boundary of the face's printed area (marked in the photograph as the B zone) is raised by several hundredths of a millimetre (enough that you can feel it) above the outer edge zone (marked A). In the central area (marked C), the case is thinner than at the edges, and can be depressed by about 0.3 mm, on each face of the battery (about 0.6mm in total). If you can view the face of the battery with light just glancing across the surface, you can sometimes see these zones.

The slight concavity can easily be sensed by rubbing the battery between the fingers and thumb.

A good way to objectively detect the expected concavity, is to hold a perfectly straight edge (like a metal ruler), against the face of the battery, and viewing against a bright background, examine how the straight-edge makes contact. You should see "daylight", meaning that some light is able to pass between the straight-edge and the middle of the battery surface.

[ 6 ] MANUFACTURING CODE

On the orientation patch end of the genuine battery, there is an impressed / engraved, 8 alphanumeric character manufacturing code.

The first character indicates the year of manufacture and (for an "S" type battery) can only be:

Obviously, the I, and H are future codes, and cannot exist now (in 2019). The second and third characters are for production month and day. We don't know with certainty the meaning of the fourth and fifth characters (a hypothesis is currently being verified), but the most common combinations seem to be "1A" and "2A". The last three characters are "P", "E", and "W", standing for "Panasonic Energy, Wuxi", the manufacturer of the genuine batteries.

Check that the code conforms to the system, that the impression is fine and sharp (and not printed), that it is correctly positioned, and that it uses the correct font. Note that it is a narrow font (check the width of the "W"), and is without serifs. Check the spacing: The letters and numbers should not be "nearly touching".

Look at where the production code begins and ends, in relation to other surface landmarks. For instance, on the genuine battery, the second half of the final W, should line up with one edge of the the retaining notch.

On the following suspect battery (image from a screen capture), the E is in that position, and the W is lined up with the centre of the notch.

(Incidentally, this notch has round corners, instead of the proper "square" corners, as in the image of the genuine battery).

[ 7 ] BATTERY WEIGHT

The weight of the NP-W126S (and NP-W126) batteries, is very uniform. Rounded to the nearest gram, the battery should weigh 47 grams (or, 1.66 oz).

Weights of non-genuine batteries might range between about 39 and 50 grams (about 1.38 and 1.75 ounces). The weight difference in non-genuine batteries, is due to different construction and chemical formula, and in the case of lighter batteries, may also be due to the use of smaller internal cells (with packing used, to fill up the empty space).

[ 8 ] MATERIALS

PLASTIC TYPE
The case of the genuine battery is made of from polycarbonate. Counterfeits may use other types of injection molding plastics. When photographed in Infra-Red (IR) light, different plastic types may show different levels of absorption and reflection, despite being the same shade in visible light. Gate marks also show up more clearly under the IR illumination.

In the above photograph, the upper and lower batteries of the stack were genuine Fujifilm batteries, while the middle battery was non-genuine. Under IR light, the non-genuine battery's different type of plastic appeared much lighter. The IR photograph (converted to monochrome) was taken using an un-modified X-T3 camera, with Infra-Red only illumination (no visible light), but no special lens filter.

[ 9 ] THERMISTOR

The thermistor allows the battery's charging and discharging temperatures to be monitored. In general, only the genuine OEM batteries have a functioning thermistor. If you have a digital multi-meter (DMM), you can easily check if the battery has a functioning thermistor. Measure the resistance between the [T] contact and the negative contact of the battery.

Take note of that resistance in kΩ (kilo-Ohms). At comfortable room temperatures it might typically be between 7 to 20kΩ.

Now slightly warm the battery by placing it under the armpit or between the two palms of the hands, for several minutes. Finally, measure the resistance again. There should have been a significant drop in resistance, of at least several kΩ. This temperature dependent variation in resistance indicates a functioning thermistor. If there is no functional thermistor, then the thermistor circuit will have been replaced by a fixed-value 10kΩ resistor, connected between the [T] contact and ground, on the battery's internal power board. The non-genuine battery manufacturer has to do this, because the BC-W126S battery charger won't initiate charging unless it sees an acceptable resistance at the [T] contact. In this (non-genuine) case, the resistance will remain at 10kΩ, continuously indicating to the charger that the battery is at a "safe" 25° Celsius (77° Fahrenheit), regardless of the battery's true temperature.

[ 10 ] TYPE "S" INDICATION

A genuine NP-W126S battery will register as such when inserted into an X-H1 or X-T3 camera (it will have a white battery symbol, rather than the "non-S" type battery's yellow symbol), however, earlier cameras such as the X-T2, will not display such a distinction.

Note that it is possible for a fake NP-W126S battery to trick an X-H1 or X-T3 camera into identifying it as an "S" type, and showing with a white display. This is because the camera distinguishes between "S" and "non-S" type batteries by interrogating the resistance on the [S] contact of the battery, and this value can easily be manipulated by an un-authorised battery manufacturer. You can verify this by placing a small piece of tape over the [S] contact of a non-S (genuine or third-party) battery, and loading it into an X-H1 or X-T3 camera: the battery will now register as an NP-W126S battery. Importantly, however, a genuine NP-W126S, will always show a white battery display, so showing yellow would indicate that it is not a genuine "S" type.

Even if you don't have an X-H1 or an X-T3, you can still test whether the battery gives an "S" type indication, by using a DMM. This is tested by checking the resistance between the [S] contact and the negative contact of the battery.

The genuine "S" type battery will show a resistance of about 680kΩ.

[ 11 ] DISCHARGE CHARACTERISTICS

Because of their different chemistry, the non-Fujifilm batteries have different discharge characteristics. This causes the battery level display (which is calibrated for the genuine battery), to behave abnormally, during heavy usage.

[ 12 ] IN-SERVICE SIGNS

It is generally not possible for the user to open and chemically analyse a lithium-ion battery. However, the different chemistry and support electronics of the non-genuine battery, can be inferred by operational discrepancies. If a counterfeit is put into service, we may experience some of the following issues:

[ 13 ] SELLER 'S ONLINE DESCRIPTIONS

A case study: This is from an offer by an eBay seller in the United States. Screen captures have been redacted, so that the seller is not identified. The first suspicious feature of this offer, is a price well below the genuine battery's typical market price, without any reasonable explanation for the low price.

Next, although the "Fujifilm" brand-name appears prominently in the title, it actually points to the applicable cameras, rather than the battery. So, instead of saying the battery is a "Fujifilm NP-W126S Battery for X-T2 (etc.)", it says an "NP-W126S Battery For Fujifilm X-T2 (etc.)". And, if you read the "Item Specifics" section, the Brand is specified as "Unbranded", despite the accompanying photograph showing a "Fujifilm" branded battery.

Significantly, the product description includes this message: "Note that this battery is not compatible with the XH-1 Camera", (an absurd statement, since the NP-W126S battery is the prescribed battery for the X-H1). The reason for making this statement is because this fake battery would give a yellow battery-level display in the X-H1, alerting the user that the battery is not a true NP-W126S at all. Finally, throughout the description, the seller never actually refers to the battery as "genuine". Based on these facts, it would appear that the seller is aware that the battery is a fake, but is attempting to sell on the basis of Caveat Emptor ("Let the buyer beware"). However, if the battery is a counterfeit (the pictured battery is virtually identical to an original Fujifilm battery, and bears the Fujifilm corporate brand logo), and if the seller knows that it is counterfeit, then it is a case of trafficking in counterfeits, which is illegal under US federal laws, as well as many other national jurisdictions.

[ 14 ] REPORTING COUNTERFEITS

Re-badging non-genuine batteries as "genuine", and attempting to deliberately deceive buyers in order to secure unlawful gain, is a type of fraud, and as such, has serious legal consequences.

Typically, we don't know who the original perpetrator of the fraud is. But we almost always know who the retail seller is, so you should seek redress from the seller. (The seller may not be aware that the batteries are counterfeit, although they really should suspect such, based on their lines of wholesale supply). Request that a full refund be issued, and that any other similar batteries to be withdrawn from the market.

If the seller refuses your request, and if the fake battery was bought on-line, you should escalate to reporting the fraud to the online marketplace that you used. Depending on whether the seller is within, or outside of, your own country, some of the following organisations may be interested in being alerted to vendors who are selling counterfeits:

Fraudsters depend on the potential buyer's lack of familiarity with the genuine product, to be able to accomplish their deception. By educating yourself and others, you not only protect yourself from monetary loss, and possible damage to your person or camera, but you also decrease the attractiveness of the battery supply market as a place for fraudulent enterprise.

[ Last up-dated: 25 June 2019 ]

THANKS FOR READING !

NP-W126S Counterfeits

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The Great Battery Brawl

Fuji versus 3rd Party NP-W126/S

in a 12 Round Contest

" I need a new battery for my Fujifilm X-series camera. Should I buy the genuine Fujifilm OEM (Original Equipment Manufacturer) battery, or should I buy an alternative 3rd Party battery?"

With this question, you have just re-ignited a conflagration, a battle of opinions that has been raging for years. Those backing the 3rd Party Contenders, claim that you are just wasting money by buying the Fujifilm OEM battery, because the best 3rd Party batteries can deliver similar performance at a much lower price. The response from the OEM Champ's backers, is that any monetary savings represent false economy when the other "costs" of using a 3rd Party battery are taken into account (for example, they claim that safety is compromised). Well, it's time to finally settle this dispute. So now, get ready for the ultimate decider. But don't expect a knock-out; this will probably go down to a points decision. Be prepared to exercise minute attention to technicalities, because in this ring, YOU will be the referee, and the ultimate adjudicator. The contest will go a distance of 12 rounds:

1 - Price
2 - Capacity
3 - Discharge characteristics
4 - Temperature management
5 - Battery swelling
6 - Power capability
7 - Self discharge
8 - Battery ageing
9 - Control codes
10 - Warranty
11 - Reliability
12 - Ultimate value

" OK, Batteries. I expect a good, clean fight.
Protect yourself at all times.
Now, return to your corners and come out at the bell. "

[ 1 ] PRICE

Price is, of course, the pivotal issue of the contest, and we could even say, the " sine qua non" issue of the fight, since if there was no price difference between OEM and 3rd Party batteries, most people would just buy OEM.

PRICE DIFFERENCES
There can be very significant price difference between the Fujifilm OEM battery and even the most costly of the 3rd Party batteries. So it is understandable that people might consider the use of alternative batteries to the OEM battery.

In the above table (based mainly on the US market), the OEM battery has been assigned a value of 100 price units, simply to make relative costs more apparent, since they can be treated as percentages. For each of the batteries listed, the current $US price is about two-thirds of the "price units" value given (except for Patona brand which is not distributed in the US, and so, does not have a regular US "street" price).

COST VERSUS SERVICE LIFE
The OEM battery supporters claim that the 3rd Party batteries don't last as long as the OEM battery. But even if this is true, the shorter life is offset, to some extent, by the lower cost. To explore this, let's assume that the OEM battery can provide a service life of 4 years, or 48 months (which, based on experience, is a realistic assumption). Now compare it to a hypothetical 3rd Party battery, costing 35% of the OEM battery's cost (that would put it in the upper price group of 3rd Party batteries). This hypothetical battery's service life would have to be reduced down to about 18 months, before it started to become un-competitive with the OEM battery, on the basis of cost. If the hypothetical battery's service life turned out to be longer (which is likely for its price category), then the cost advantage over the OEM becomes even more compelling.

Of course, a shorter service life means that you have to purchase more batteries in order to match the OEM's 48 months of service. This repeating battery purchase produces other effects.

BUDGETARY ADVANTAGE
Assume a hypothetical 3rd Party battery, which only costs one third of the OEM cost, but only lasts one third of the OEM life. You would have to buy a second one, and then a third one, later, to match the life of the OEM battery. In the long run, the users of the 3rd Party battery, and the users of the OEM battery, both spend the same total amount of money over the same period of time. However, the lower cost battery effectively allows the user to spread the battery costs, and pay one-third now, one-third later, and another third later still. The user may appreciate this as a significant budgetary advantage.

MORE FREQUENT BATTERY FADE PERIODS
On the other hand, frequent battery renewal, comes with a more frequent experience of transitional service, due to battery fade. In the transition period (when the battery is coming to the end of its life), the battery goes from performing acceptably, to performing unacceptably. This period can be marked by annoying, unreliable, and uncertain battery behaviour; shots per charge drops rapidly, and the possibility of unanticipated "low battery" shutdowns is increased. You might prefer not to go through this transition period any more often than is necessary. However, if the 3rd Party battery can match the service life of the OEM battery, this argument has no merit.

PRODUCTION OF WASTE
Some people say "Buy cheap batteries, and just replace them frequently". However, if we again take the case of the hypothetical "one-third-price, one-third-life" battery, it could be argued that this battery produces three times as much waste (and three times the carbon footprint of production), because you have to buy three of them, rather than a single OEM one. In the long-term, the longest life battery (which may be the OEM battery), produces the least waste. This is an issue rarely raised, in the debate, but perhaps it should be, given our rising consciousness of environmental issues.

DELIBERATION
For the price issue, there are are reasonable arguments from both sides of the debate. But, although price differences are clear and substantial, there is a saying that "money is not everything", and a decision based on this criterion alone, may be superficial. The implications of battery choice are multivariate, and there are other significant issues that we need to consider. We will revisit the price issue when we eventually look at ultimate value.

[ 2 ] CAPACITY

Many 3rd Party batteries seem like a great "buy" because, not only are they cheaper than the OEM battery, but they also boast a higher capacity. Unfortunately, battery capacity is a complex topic, which is often poorly understood. It is worthwhile exploring this area in some depth. Let's try to make sense of the numbers.

The NP-W126S battery is a nominal 1260mAh (milli-Amp-hour) battery. The 1260mAh capacity is indicated by the "126" in the battery's name, which is the capacity, with the final zero dropped. In the same way, the GFX camera's NP-T125 battery is a 1250mAh battery (with the final zero dropped to give the name). This is Fujifilm's current battery naming practice for these and any new twin cell (NP-Wxxx, W indicating tWo or tWin), or triple cell (NP-Txxx, T indicating Three or Triple) batteries. (Note that the naming system used for the older single cell batteries is different).

The genuine OEM NP-W126/S battery was designed around the Panasonic NCA673440 prismatic lithium-ion cell. ("Prismatic" differentiates the shape from cylindrical and pouch type cells).

There are two of these cells in each battery. For reference, this cell has a volumetric energy density of 0.47 Watt-hours per cm³, and a gravimetric energy density of 0.213 Watt-hours per gram.

Recognition of the dual cell nature of this battery will be important for understanding some of the "capacity" concepts, and will help avoid some specification misunderstandings.

ELECTRICAL SPECIFICATIONS
The Fujifilm NP-W126S battery has 5 electrical specifications printed of its front face:

Because the battery's terminal voltage continually reduces during discharge (going from 8.4V down to 6.0V), the battery is assigned a "nominal" voltage, which is the half-way point between maximum voltage (8.4V) and minimum discharge voltage (6.0V).

3rd Party batteries typically state only the nominal voltage, nominal capacity, and the nominal energy of the battery.

Although photographers may pay little attention to the nominal energy specification, it is required to be stated on the battery for the purpose of determining compliance with air-transport regulations, because it is a better indicator of the amount of energy that could be released in an explosive or rapid combustion event. Using the nominal energy specification, batteries are differentiated into one of three categories (less than 100Wh, up to 160Wh, and over 160Wh), in order to determine which air transport rules apply to them (for instance, how many spares a passenger is allowed to carry). Stills camera batteries are all in the lowest (< 100Wh) category. For reference, one Watt specifies a power of one Joule per second, and one Joule is equivalent to one Newton-metre.

COULOMETRIC CAPACITY
This is the specification most people think of when considering capacity. The nominal, or coulometric, capacity, specifies a current (a flow of electrical charge) which can be sustained for a one hour period of time, and is expressed in milli-Amp-hours (mAh). The NP-W126S's 1260mAh nominal capacity can, in theory, continuously supply 1260 milli-Amps of current for 1 hour, or the various mathematical equivalents, such as, 630mA for 2 hours, or 2520mA for half an hour, etc. In practical terms, the nominal or coulometric capacity is an indicator of how much use we can expect to get from the battery before it requires recharging. In photographic terms, it will be a major factor in determining how many shots we get per battery charge. Coulometric capacity is closely related to the battery's internal cell size (and the volume of active material contained within the cell), but it is not directly related to total battery size, since it does not take into account the number of internal cells which comprise the battery.

ENERGY CAPACITY
The other measure of battery capacity is the battery's energy capacity, or nominal energy, expressed in Watt-hours (Wh). The nominal energy can be found by multiplying the capacity by the nominal voltage. So, for the NP-W126S battery, the nominal energy would be: (1.20Ah x 7.2V) = 8.7Wh. (Note that Fuji uses the minimum capacity, 1200mAh, rather than the typical capacity, for this calculation). The nominal energy is often overlooked, however it does put battery capacity into a different perspective, and also resolves the "typical capacity" anomaly that can be noticed when, for instance, comparing the three different sized batteries in the following table.

It might seem counter-intuitive that the biggest battery (the NP-T125), has the smallest "typical" capacity, while the smallest battery (the NP-95) has a significantly higher capacity. To simplify the explanation of the difference between the two types of capacity specification (energy and coulometric): one specification answers the question "How much?" (energy), while the other answers the question "For how long?" (running time). The battery's nominal energy, expressed by its Watt-hour (Wh) rating, takes into account the voltage of the battery, and that normalises the relationship between size and "capacity". The voltage will depend on the number of cells in the battery pack, which ranges from single to triple, for still camera batteries. The cells are connected in such a way that their individual voltages (3.6V) add together, but the total mAh capacity does not change from that of a single cell. All NP-W126 type batteries, will be twin cell, and have a reference voltage of 7.2 (or 7.4) Volts. Because the nominal voltage is a mid-point voltage, between maximum voltage and lowest allowable discharge voltage, if the manufacturer uses different end-points (specifically, a different minimum discharge voltage), then the mid-point voltage can vary. This explains why some 3rd Party batteries state their nominal voltage as 7.4 Volts. However, the 7.2 Volts and 7.4 Volts are only "indicative" voltages, and they effectively point to the same characteristic voltage.

DIFFERENCES IN MARKET CAPACITIES
The reason the Fujifilm NP-W126S battery has a nominal capacity of 1260mAh is, because that's about the capacity limit for a battery of that size within the constraints of the current lithium-ion technology. Since the OEM and 3rd Party batteries are all the same size (they have to be, in order to properly fit the camera's battery chamber), why do the various 3rd Party battery manufacturers specify different capacities? A survey of 3rd Party NP-W126 batteries on the market currently, has batteries ranging from 1600mAh down to 950mAh. (I did not include the claimed "1900mAh" batteries, on the basis of their lacking credibility).

There are several explanations for this wide discrepancy in quoted capacities for batteries of the same physical size:

CAPACITY TESTING CONDITIONS
In testing, the capacity may have been determined at a different discharge rate (C-rate) than the OEM battery. Since capacity varies with C-rate (an effect called capacity offset), this can lead to differences in the reported capacities. If the discharge testing is performed at a low discharge current, the measured capacity will be higher, and if performed at a high discharge current, the measured capacity will be lower. When increasing the C-rate from 0.2C to 1.0C, the capacity reading is decreased by about 10%. Capacity testing at different ambient temperatures will also cause variation in the reported capacities. For instance, a battery that recorded 1220mAh of capacity when tested at 25°C (77°F), might only record 1200mAh when tested at 20°C (68°F).

The Fujifilm battery specification is based on a discharge rate of 1.0C, at 25°C / 77°F. Full specification data sheets for lithium-ion cells (like the NCA673440) will specify the C-rate and ambient temperature at which the capacity was determined. However, similar information for the internal cells of 3rd Party batteries is, in practical terms, "un-discoverable" for most battery users.

TYPE OF SPECIFICATION
The manufacturer can have quoted either the maximum capacity, the typical (or average) capacity, or the minimum (or rated) capacity. The capacity could also be an indicative capacity based on theoretical calculations (for example, cell weight multiplied by the typical gravimetric energy density ), rather than practical measurements. Most frequently, it it not stated which of these specifications is being used.

OPTIMISATION
The specific design of a battery's electrochemistry either optimises it for Power, or optimises it for Capacity, but the battery can't be optimised for both. The power oriented battery is able to answer demands for continuous high current (such as might be needed for shooting 4k video). In contrast, the capacity oriented battery, is able to supply low power photographic use (single-shot stills shooting, at a low rate), for a large number of shots.

Because of this difference between power optimised and capacity optimised batteries, it is possible for a 3rd Party battery to get more shots per charge than the OEM battery, but then perform poorly when supplying power for high definition video, or high frame rate, continuous shooting.

LOWER CAPACITY CELLS
A lower quoted capacity may indicate smaller internal cells, so there is less active material (the substances responsible for the electrochemical activity which produces the electricity). That reduction in the amount of active material would show up as a measurable reduction in battery weight. Note that even a slight decrease in the cell's linear dimensions, can produce a significant decrease in volume, weight, and nominal capacity. For instance, compare the NCA673440 with the FT603040 lithium-ion cell, which appears to be about the same size:

(The chart also shows that the string of numbers in each cell name, actually indicates the approximate cell dimensions). The OEM battery weighs 47 grams or 1.66 oz (20.3g for each cell, and about 6.4g for the circuit board and case). The lower capacity battery's weight may go down to around 40 grams or 1.4 oz (with about 15g per cell, plus a few grams of packing material, to hold the slightly smaller cells in position).

Lower stated capacities are probably reliable, since there is little market advantage to be gained by quoting a lower capacity than the competitors. One important point regarding lower capacity batteries, is that they are more likely to overheat while charging, leading to swelling. This is because the charger is typically designed to charge a 1200mAh battery, so the charging current might be higher than is optimal for the lower capacity battery.

CONFUSED SPECIFICATIONS
A 3rd Party battery producer (the battery assembler, rather than cell manufacturer), may be confused about the conventional way of determining or stating a battery's electrical specifications. The problem is typically due to a confusion between cell specifications, and battery specifications (A battery is a cluster of cells, in the case of the NP-W126 battery, two cells). Specifically, there can be confusion over whether or not a particular specification should be doubled, due to the use of two cells in the battery.

In the first example (shown above), the stated voltage of 3.7V, is the cell voltage, where they should have stated the battery voltage of 7.4 Volts (2 x 3.7V). As a consequence, the nominal energy specification of 3.5Wh is also wrong; It should have been 7Wh. In the next example, the nominal capacity is stated as 1360mAh.

Upon opening the battery, the internal cells were found to be 680mAh capacity (from the cell manufacturers specification sheets). The battery capacity should have been stated as 680mAh, and should not have been doubled to give 1360mAh. My experience is that this error is quite frequent. Be wary of any NP-W126 type battery stating a capacity higher than 1300mAh. You will often find that they are actually half the stated capacity. However, they can still work well, even if giving less shots per charge than the OEM battery.

EXAGGERATED SPECIFICATIONS
The final reason for a wide variation in capacities is that the battery may have its specifications mis-represented, or exaggerated. At least one battery on the market boasts 1900mAh capacity, but actually delivers less than 700mAh.

Erroneous "doubling" of 700mAh would only have given about 1400mAh (still on the high side). If the discrepancy between claimed and actual capacity is significant, and intentional (with the goal of deceiving), then the battery is a fraudulent battery. There is no need to consider these un-trustworthy batteries any further.

TRADE-OFFS
If the battery is specified as a higher capacity than the OEM battery, you should reflect upon why this could be the case, and take that into your considerations. Don't expect to get higher capacity than the OEM battery, without some other trade-offs, which could be in terms of, poorer performance under heavy loads, increased self-discharge rates, decreased battery life, etc.

DELIBERATION
Due to the reasons given above, it it typically not very productive to compare batteries on the basis of their self-quoted capacities. Also, to get battery performance that is similar to the Fujifilm OEM battery, the 3rd party manufacturer should strive to use battery chemistry close to that of the OEM battery, and so we would expect a similar (not higher) mAh capacity. Highly respected 3rd Party batteries like Watson and Patona, quote capacities that are very similar to the OEM battery's capacity. My own experience, and that of many others, is that the best 3rd Party batteries can deliver a capacity similar to the OEM batteries. However, even with a genuinely equivalent capacity to the OEM battery, there may still be differences in power delivery rate, self-discharge rate, and ultimate rate of decline in battery's SoH (State of Health). So, although capacity need not be a deal breaker issue for the OEM vs 3rd Party decision, it is not the only performance specification that needs to be considered.

[ 3 ] DISCHARGE CHARACTERISTICS

Discharge characteristics can be an issue, because they affect the feedback that the camera gives to the user, regarding the battery's State of Charge (the remaining charge of the battery). This is what is indicated by the battery level display when we are using the camera. The battery level indicators of the Fujifilm X-series cameras, are calibrated for the Fujifilm OEM batteries. Because other batteries differ in their chemistry, they produce different discharge curves (voltage plotted against capacity).

Not only are discharge plots non-linear, but those typical of 3rd Party batteries also have a different shape and more prominent inflection points, in comparison to the OEM batteries. Because of this, the battery level indicator produces some anomalies when using these 3rd Party batteries.

A typical experience when using 3rd Party batteries under high power discharge situations (4k video, or high frame-rate continuous shooting), is that the charge-remaining indication is exaggerated (the actual capacity is less than what is shown), and there is little or no warning given of immanent shut-down due to battery depletion. Frequently, the indicator goes from two bars directly to empty.

For some photographers, this is both annoying, and disruptive of workflow, due to insufficient warning of power shut-downs. Other photographers just adapt, and prepare for a battery change whenever the "two bars" indication is reached. Besides, if you are not putting extreme demands on the camera, the effect is much less noticeable.

OLDER CAMERAS
If you are using an older X-series camera (pre X-T2), any display differences due to different discharge characteristics, may be a minor issue.

The older battery level display lacked resolution, and may not differentiate OEM from 3rd Party batteries in any meaningful way.

DELIBERATION
This issue does not actually affect the battery's functionality in terms of capacity, shots per charge, or life expectancy. It might be considered as an issue affecting the quality of the user experience, and its significance, will very much depend on your personal tolerance for such technical anomalies.

[ 4 ] TEMPERATURE MANAGEMENT

Temperature management is a critical issue for lithium-ion battery safety and service condition. Although reported cases of catastrophic failure are fewer than with, as an example, notebook computer batteries, incidents with camera lithium-ion batteries do occur. Reported cases of camera battery related venting and combustion events include: A camera battery catching fire on an aircraft departing Chicago O'Hare Airport in 2013, a smoking camera battery at Raleigh Durham Airport (North Carolina) in 2017, an exploding camera battery at Orlando International Airport in 2017, and a camera battery catching fire (while charging) in Norway during 2018. Probably, most incidents occurring in a domestic context are not reported.

Extreme temperature conditions can both damage the battery, and/or render it unsafe. When being charged, lithium-ion batteries must not go outside of the temperature range 0°C to 45°C (32°F to 113°F). At temperatures below 0°C / 32°F, metallic lithium becomes permanently plated on the cell's anode (effectively producing a loss of available lithium salts for the electro-chemical process), and ion diffusion rates on the anode are reduced. At temperatures above the upper allowable range, there is cumulative and permanent loss of capacity and reduction in charge acceptance.

If a lithium-ion battery reaches about 150°C (about 300°F), it may vent (the cell's pressure relief valve opens, or its "burst plate" ruptures, to relieve pressure).

During venting, not only are highly flammable gases released, but electrolyte can also be released as liquid, droplets, or vapor. If venting occurs while inside the battery chamber, the battery can leak hot electrolyte fluid (containing solvents) from its terminal openings, into the battery chamber. Electrolyte leakage will be noticed as a black residue in the terminal area. In the worst case scenario, if the battery is able to reach a temperature of over 200°C (390°F), second venting and thermal runaway can occur. Thermal runaway will be the prelude to a violent incendiary event.

Because of the hazards posed by lithium-ion batteries, if operated outside of their "safety envelope", all lithium-ion camera batteries include a circuit board for battery management and protection. Ideally, the circuitry should maintain balanced cell capacities, and guard against deep discharge, overcharging, short-circuit or over-current, and temperature range violation. The following image shows a circuit diagram representing is a protection circuit arrangement.

At a minimum, the circuit board typically uses a purpose-designed lithium-ion controller IC, combined with a MOSFET (metal oxide semiconductor field effect transistor) device for on/off switching of current.

Below is shown the actual protective circuit board (which also serves as the terminal board), of an Fujifilm NP-W126 battery.

Besides the positive and negative battery terminals, the protection board for the NP-W126/S or equivalent batteries, also has circuitry connecting to [S] and [T] terminals, so that there are four battery terminals.

The [T] terminal (standing for either Temperature or Thermistor), is (or should be) integral to the thermal protection of the battery while charging.

OEM USES THERMISTOR
The Fujifilm OEM battery uses a thermistor (implemented as a tiny surface mount device on the battery's protection circuit board), for temperature management. A thermistor is resistor whose resistance output is highly temperature dependent.

In its NTC (negative temperature coefficient) form, the resistance is inversely related to the thermistor's temperature. NTC thermistors exhibits a large, precise and predictable decrease in resistance as their core temperature increases.

Other reasons for using the thermistor are, good tolerance to shock and vibration, and little need of output signal conditioning (just a single capacitor for ripple suppression). The small size of the NP-W126/S thermistor (less than 1mm long), gives a low thermal mass, resulting in minimal lag for measurement of rapidly changing temperatures. The thermistor outputs a 10kΩ (kilo, or thousand, Ohm) resistance at a temperature of approximately 25°C (77°F). A reduced resistance indicates an elevated temperature, and vice-versa. The [T] terminal of the BC-W126S charger (or the camera, if utilising in-camera charging) reads the resistance on the battery's [T] terminal, and is able to determine the battery's internal temperature, and decide whether it conforms to the safe-charging temperature limits. Charging is terminated if the battery temperature goes outside the safe range.

NO THERMISTOR IN 3rd PARTY BATTERIES
Although it would seem reasonable to assume that 3rd Party batteries would implement this same thermistor driven system of charge-temperature management, it is generally not the case. 3rd Party batteries generally do not employ a thermistor. However, simply omitting the thermistor is not really an option, because the Fujifilm chargers (and cameras capable of in-camera charging), will not allow charging to initiate, unless a resistance indicating a temperature within the safe operating range, is found on the battery's [T] terminal. (You can verify this by placing a small piece of tape over just the [T] terminal of any "NP-W126" battery, and trying to charge it in a Fujifilm charger, or by using in-camera charging; charging will be blocked). In order to fulfill this "valid resistance" requirement, the 3rd Party batteries typically use a simple fixed-value, 10kΩ resistor in place of the thermistor circuit. The fact of the 10KΩ resistor substitution, is verified, not only by measuring resistance at the [T] terminal over a wide range of temperatures, but also by "cracking-open" various 3rd Party batteries, and examining the circuit boards. Note that the charger (or camera) is unable to tell whether the resistance being read is output from a thermistor or fixed value resistor. If you have an understanding of printed circuit boards and know what a "via" (vertical interconnect access) is, you will be able to trace the 3rd Party battery "T" circuit on the following image.

The result of using the 10kΩ fixed-value resistor, is a battery which tells the charger or camera, that the internal battery temperature is a very acceptable 25°C (77°F), regardless of the actual battery temperature, and even if the actual temperature is outside the safe range. Although precision grade (limited variation from the nominal specification) and aged (which reduces the tendency to "drift") thermistors can be costly, it is probable that using a resistor rather than a thermistor, also has some fabrication and assembly advantages for the 3rd Party battery maker, besides cutting component costs.

CONSEQUENCES OF NO-THERMISTOR
Likely consequences of not implementing the thermistor circuit are that, each time the charging process transgresses the allowed temperature range, the battery sustains some cumulative and non-reversible damage. Its performance might decline (and a corollary of this would be a reduction in service life), and the battery may eventually begin to swell, due to internal pressure caused by the over-heating, with the possibility of becoming stuck in the camera's battery chamber. Less-likely (based on the relative infrequency of reports) but more extreme consequences are the battery catching fire or exploding.

TEMPERATURE MANAGEMENT AS A SYSTEM
Does that mean that by using an OEM battery, my charge process is always temperature protected? Actually, "No". Importantly, thermistor temperature management is a system , which not only requires the battery's ability to send its temperature information, but also the charger's (or camera's) ability to read and interpret that temperature information.

So, if you have a Fujifilm OEM battery (with thermistor), but you are using a 3rd Party charger with no [T] terminal, the thermistor data is virtually useless, because the charger has no way of reading it. If you are using a USB charger (which Fujifilm does not offer), you may notice it has no [T] terminal, and therefore there will be no temperature management advantage by OEM batteries over 3rd Party batteries, despite having a thermistor.

An exception to this, is the Nitecore FX1 dual (the second battery bay is on the underside) USB charger, which does have a [T] terminal, to monitor the thermistor readings. However , protection, in this case, is not automatic. The FX1 charger will report the correct temperature of a thermistor equipped battery, but it does not terminate charging if the battery goes outside the 0°C to 45°C allowable charging temperature range. The user needs to stop the charging process if they notice that the temperature display is approaching the 45°C charge temperature limit. [Thank you to Michael Kluth, who provided further valuable information regarding the FX1 charger 's operation].

However, in-camera or in-grip charging, always accesses the [T] terminal, which is why older Fujifilm cameras like the X-T1, which only had two battery terminals in the battery chamber, could not have implemented in-camera charging.

If you are using a two terminal ( [+] and [−] only ) charger, then the having or not having a thermistor by the battery, becomes an irrelevant factor. On the other hand, the JJC DCH-NPW126 USB dual charger has a temperature sensor built into the body of the charger, and this should extend over-temperature (but probably not under-temperature) charge protection to all batteries, whether they have a thermistor or not.

The Watson Duo Charger also states in the Owner's Manual (page 5), that it provides overheat protection: "The Duo Charger senses when the battery is about to overheat and immediately stops charging".

Once again, the heat sensor must be built into the charger, because the battery mounting plates do not have contacts to read a thermistor built into the battery. (There may be other chargers with built in temperature sensor, but I am unaware of any verified alternatives, at the moment).

The charge temperature management that you get (or don't get), depends on your combination of battery and charger setup. By selecting an appropriate battery-and-charger combination, you can ensure protection from over-heating, even when using 3rd Party (no thermistor) batteries.

COLD CLIMATES
If you are living in a very cold climate, and you are not using high C-rate charging, battery over-heating while charging may not be an issue. It is normal for the battery's temperature to rise by about 5° of the Celsius scale, or 9° of the Fahrenheit scale, during moderate C-rate charging. In very cold conditions, the battery's temperature might be able to rise by several times that amount, without getting close to the upper limit for charge-temperature. In cold climates, your main problem may be to ensure that you do not attempt to charge the lithium-ion battery at freezing or sub-freezing temperatures (which will severely damage the battery, due to lithium plating).

HIGH CHARGE RATES
Batteries become hotter when charged using high currents, so charge rate is relevant to temperature management. C-rate specifies the limiting current during charging or discharging of a battery. The C-rate is the ratio between capacity (in milli-Amp-hours) and current (in milli-Amps), normalised against a time period of one hour. So if we use a 1200mA current to charge a 1200mAh battery, (a ratio of one to one), the charge time would be (in theory), one hour, and the C-rate would be 1C. If we used 600mA of current to charge the same 1200mAh battery, the time taken would be two hours, and the C-rate (only half the charging efficiency of the first case), would be 0.5C. Please note that, during the second half of the charge process (the saturation phase), the current rapidly drops below the value represented by the nominal C-rate, so you cannot accurately calculate charging times, based solely on the C-rate.

For a 1200mAh battery, 0.7C or higher is considered a "high" C-rate, which would indicate a charge current of about 840mA, or higher. It is generally not advised to charge batteries of the NP-W126/S type, at C-rates higher than 0.7C (although the Fujifilm BC-W126S charger can output 0.75C, compared to the 0.6C of the previous BC-W126 charger). Most of the regular (not-fast) chargers use a C-rate of about 0.5C (so, current value is half the capacity value), which gives a charge current of about 600mA. In comparison, the Nitecore FX1 charger is rated at a maximum output current of 1000mA, and so it would be considered a "fast" charger.

This high charge rate is possible because because the user can monitor the temperature on batteries that have a thermistor. (But what if the battery doesn't have a thermistor, and so tells the charger that it is 25°C, regardless of its actual temperature?)

DELIBERATION
On the issue of charge temperature management, the battery cannot be considered in isolation from its intended method of charging. If you are considering a setup that does not implement charge-temperature management, you should satisfy yourself that the risk of battery swelling, or even of a catastrophic-failure type charging event is minimised and acceptably small.

[ 5 ] BATTERY SWELLING

Battery swelling is a common phenomenon with some 3rd Party batteries. However, it is virtually unknown with properly charged and used Fujifilm OEM batteries. The several cases I know of, where the "Fujifilm" battery was reported to have swollen, each turned out to be a counterfeit battery.

CAUSES OF SWELLING
Swelling, where the central thickness of the battery noticeably (and permanently) increases, indicates that the battery has been overheated, usually during charging. Overheating produces gasses, mainly hydrogen and carbon-dioxide, as well as carbon monoxide and ethylene (C2H2) from reduction of the ethylene-carbonate electrolyte. This evolution of gases increases the internal pressure of the two prismatic cells, and causes deformation tending towards a spherical form, because the round shape distributes the pressure induced stresses more uniformly. Because there are two prismatic cells, there are four significant deformation surfaces. Upon cooling however, the external to internal pressure gradient is insufficient to return the cells to their original flat shapes.

TOLERANCES
The NP-W126/S battery fits the X-cameras by fairly narrow tolerances (less than 5%). On the X-T3, the battery's fit to the battery chamber allows about 0.5mm (20 thousandths of an inch) of "play" in the dimension sensitive to swelling, to allow for easy insertion. That play is equivalent to about 3% of the battery's nominal thickness.

In comparison, a heavily swollen un-branded battery that was assessed, exceeded the chamber width measurement by 0.4mm (16 thousandths of an inch), giving about 6% increase to the central thickness.

There is enough structural "give" in the battery chamber that, by pushing firmly, you would be able to fully seat the swollen battery, (which would "wedge" its way in, because the battery's ends are typically not swollen, only the centre). However, the battery will not easily release, and you may have to resort to heavily striking the camera against your hand ("inertia" release), a damaging use of tools ("extraction" release), gluing a tab to the end of the battery ("adhesive" release) or even having to partially dismantle the camera, to get the battery out.

EFFECTS OF SWELLING
A swollen battery poses the following problems. If inserted into the camera's battery chamber, it may become difficult to remove, and there is the risk of damaging the battery chamber in attempting to remove the battery. If the battery swells significantly while inside the battery chamber (this could happen if you are utilising in-camera charging of a "resistor instead of thermistor" type battery), the battery could stress, bend, or crack, the chassis and circuit boards that either form or adjoin the walls of the battery chamber. However, even if the battery does not cause camera damage, a swollen battery will continue to decline, not only in capacity but also in safety, and needs to be (properly) disposed of.

EXPANSION
Although the Fujifilm OEM battery is reputed not to swell, it is natural for most substances to expand when they are heated. Because the battery's internal cells are sealed, we would expect some (even if extremely slight), "expansion" during the normal charge process. The OEM battery has a construction which is able to manage this. The two faces of the OEM battery's polycarbonate case (and the internal cell separator) are actually membranous.

The centre thickness of this flexible membrane is only 0.25mm (9.8 thousandths of an inch). It's thin enough that light will pass through it.

As well as this, the membranous surface is concave (curving inward) in shape, with the centre of the faces shallower than the edges of the case, by about 0.3 mm on each side.

This thin and flexible construction gives a case that is able to expand slightly in its middle thickness, without actually altering the nominal specifications. Therefore, any slight expansion (not enough yet to be considered "swelling"), by the OEM battery, can be accommodated. The practical difference between expansion and swelling, is that expansion is reversible (the deformation to the cell case has not exceeded the case material's elasticity yield-point), while the deformation of swelling has "passed the point of no return". In theory, the OEM battery could expand by up to 0.6 mm in its middle thickness, and still maintain the full 0.5mm "play", and without making any difference to the battery's fit in the chamber, or to its ease of ejection.

DELIBERATION
The risk of battery swelling is one of the main arguments used by the proponents of the "only use OEM batteries" position, and for some people, is a deal-breaker with regard to using 3rd Party batteries. However, that risk may be mitigated by, over-heat protection while charging, avoidance of in-camera charging, living in a cold climate, and your own careful attention to the condition of the battery, and to any changes it displays. Also, check on-line forums for whether a particular brand of batteries has a reputation for swelling (some do).

[ 6 ] POWER CAPABILITY

Whereas energy capacity (in Watt-hours) is concerned with the battery's capacity to store electrical energy, power (in Watts) is concerned with the ability to deliver that energy, for use. The ideal is that all of the released energy should be available to power the camera, but due to various inefficiencies, some energy is always lost as heat.

In the following, the ability to release high usable power, while limiting heat related losses, will be referred to as the performance level of the battery. The Fujifilm X-series camera batteries have evolved from a standard performance level (the NP-W126) to a higher performance level (the NP-W126S battery). The newer NP-W126S battery, replaces the NP-W126, even though its higher performance level is not required by the older (pre-XT2) X-series cameras. Importantly, there is no difference between the two battery types, in either energy capacity or coulometric capacity, since this performance issue is related to battery heating, and the battery's rate of power delivery.

PROPRIETARY INFORMATION
How the battery's manufacturer, Panasonic Energy, was able to realise the performance increase, is proprietary information. However, the problem that they addressed would typically have involved one or several of the three electrochemical overpotentials or polarisations (activation polarisation, concentration polarisation, and ohmic polarisation) which reduce a battery's power efficiency, and ultimately lose electricochemical energy as heat. Considering that the physical and electrical specifications of the type "S" battery remain unchanged from the original, the improvement strategy most likely involved the use of electrolyte additives to improve the battery's electrochemical efficiency. Whatever the precise improvement strategy, such information is rightly considered an industrial secret, so it is not a situation where the competitors can simply copy and apply the same solution.

" S" VERSUS "NON-S"
In practice, the higher performance "S" battery can work at power levels where the standard performance battery might not be able to keep up with the power demand. The standard performance battery's failure to meet that demand, may even trigger a camera lock-up event.

In order for the latest high-performance cameras to know whether the loaded battery "can deliver" in these high demand situations, the batteries have a way of "signalling" their class of performance level. This information is supplied over the battery's [S] terminal. After assessing the type, the camera indicates the type to the user, by way of alternative colours (yellow or white) for the battery level indicators, and by way of a possible advisory message at power-up time, on cameras where the difference matters (such as X-H1 and X-T3).

YELLOW OR WHITE
When a battery is loaded into a capable high-performance camera (X-H1 or X-T3), the camera interrogates the resistance on the [S] terminal of the battery. If the resistance is 100kΩ, the camera determines the battery to be either an OEM NP-W126 battery, or a 3rd Party equivalent, and the battery level display is in yellow. However, if the resistance shows as 680kΩ (thus exceeding a set resistance threshold), then the camera determines the battery to be an enhanced power delivery capable NP-W126S battery, displayed in white.

In this second case (NP-W126S), I did not say, "or a 3rd Party equivalent", because it is still uncertain whether there really are 3rd Party batteries that can provide the same performance level as the OEM NP-W126S battery. Definitely, 3rd Party batteries are coming onto the market, claiming to be NP-W126S equivalents, and even registering as such when inserted into an X-H1 or X-T3 camera, however, there is more to this than meets the eye.

" S" RESISTANCE
The original OEM NP-W126 battery showed a 100kΩ resistance at the [S] terminal, so the power management boards of 3rd Party batteries implemented a 100kΩ resistor to give the same reading on the [S] terminal as the OEM batteries did. That made sense, because the 3rd Party batteries were intended to be an interoperable alternative to the OEM batteries.

Now, however, we have a situation where the OEM type "S" battery (with enhanced performance) gives a 680kΩ resistance at the [S] terminal, which indicates that it is a type "S". The problem is, the manufacturer of a non-OEM battery (still using the previous, standard performance chemistry), can substitute a 680kΩ resistor for the the protection board's 100kΩ resistor (or simply omit the resistor, and leave the [S] terminal open-circuit). A battery with the appropriate [S] terminal resistance can pass itself as a high performance version, although the only thing changed was the "signalling" resistor.

EASILY MANIPULATED
You can verify that the type "S" indication can easily be manipulated, by placing a small piece of tape over just the [S] terminal of a "non-S" type battery (either OEM, or 3rd Party). This makes the [S] circuit an "open circuit", and changes the resistance to a virtual "infinite resistance", which (by definition) exceeds the set resistance threshold for type "S" indication. Insert the battery into an X-H1 or X-T3 camera, and, Voilà! Now the battery registers as an NP-W126S battery, it shows a white battery level indicator rather than yellow, and the several seconds duration "PLEASE USE NP-W126S BATTERY, etc" advisory message does not display, even though the battery has the chemistry of the standard performance type.

RELIABILITY OF "S" INDICATION
Fujifilm cameras are designed to be used with Fujifilm OEM batteries, and the purpose of the [S] terminal reading is to differentiate between different types of Fujifilm OEM batteries, not to differentiate between OEM and 3rd Party batteries. So the [S] terminal implementation gives reliable information when Fujifilm OEM batteries are used. But, the "S" indication cannot absolutely be relied upon when 3rd Party batteries are used. Just because the label on a 3rd Party battery states that it is an NP-W126S equivalent performer, does not mean that it is. And just because a 3rd Party battery registers in an X-H1 or X-T3 camera as an NP-W126S, does not mean that it will give equivalent performance to the OEM battery. Although 3rd Party manufacturers may be able to boost their battery performance to be equivalent to the OEM NP-W126S battery, the "equivalence" will depend on their performance , not on their in-camera battery indication. As an example of this unreliability, note the anomaly displayed by this pair of, otherwise identical, batteries:

A 3rd Party battery's "S" designation, is not a reliable indicator of its performance. It may be higher performance, or it may just be print and electronically labelled as such. At the moment (early 2019) I am inclined to ignore any 3rd Party battery's claimed "S" designation, and rely on my own assessment of the battery's performance.

DELIBERATION
It is not proven yet, that non-OEM batteries are able to achieve exactly the same power delivery rate as the Fujifilm OEM battery, and type "S" claims on 3rd Party batteries should be treated with caution. However, inability to achieve true type "S" performance may not be relevant, if you don't actually need it. Type "S" performance is not required by all X-series cameras, and Fujifilm even states that the cameras prior to the X-T2 will not benefit from the higher performance level. Furthermore, even if you have a camera which can benefit from the performance improvement, your own shooting style may not. If you use your camera mainly for landscape photography, for example, you are unlikely to require that performance level. If you don't shoot 4K video, if you don't use high rate continuous shooting, and if you don't have continuous auto-focus turned on all the time, you probably don't require the higher performance level. Remember, the standard performance level does not mean that you get less capacity.

[ 7 ] SELF DISCHARGE

Even without being used, a battery is always in a state of running down. All batteries are subject to a deficiency known as self discharge. An elevated level of self discharge is experienced as a charged battery which is unable to retain a high level of charge over a period of days or weeks, when not being used. The cause is an internal current flow called leakage current. Part of the leakage is due to inefficiencies in the battery's electrochemical makeup, and part is due to leakage through the protection board's circuitry. Self discharge is also highly dependent on ambient temperature, with higher self discharge rates occurring at higher ambient temperatures. Exposure to temperatures beyond the normal operating range (ie, above 45°C / 113°F) will increase the battery's future self discharge characteristics, even at normal temperatures. A low rate of self discharge is a desirable quality in a battery. A commom criticism of 3rd Party batteries is that their self discharge rate is higher than that of the OEM battery. Please note, that a battery installed in the camera body, will experience increased discharge while not being used, due to stand-by current (while awaiting a power-up signal from the camera's on-off switch), and due to powering the cameras clock-calendar. This is discharge by the camera, rather than self discharge.

BENCHMARK
A normal rate of self discharge after full charging, would be 5% loss in the first 24 hours, and a further 5% loss (2% intrinsic and 3% due to the battery's management board), over the rest of the month. So at the end of one month, the battery should still have 90% of its fully charged capacity.

MEASUREMENTS
A standard method for measuring self-discharge is to perform a standard charge, store the battery for 30 days at 25°C±0.5°C, and then perform a standard capacity test. Because there is a relationship between open circuit voltage (the voltage you would measure when the battery is not in the camera) and State of Charge (the capacity remaining), an alternative method is to to monitor a battery's open circuit voltage (with a digital multi-meter), at regular intervals over a period of days and weeks. A good result would be approximately 14 milliVolts decrease per day, after the first 24 hours.

DELIBERATION
Because self discharge reveals itself over time, photographers who charge their batteries just before use (so there is no interim period between charging and usage), may not be affected by moderate degrees of self discharge. However, in advanced cases, the loss of charge may be noticeable over a period of hours. Battery self discharge is a fact of life. The question is whether the 3rd Party battery can equal (or perhaps even better) the low self discharge characteristic of the Fujifilm OEM battery.

[ 8 ] BATTERY AGEING

All batteries decline in their capabilities over time, and eventually reach a point where their ability to perform does not meet the user's needs. In other words, batteries age and die (or at least, start to give unacceptably low performance). This process consists partly of a time driven element (calendar fade), and a usage driven element (cycle fade). A common criticism of 3rd Party batteries is that their service life is shorter than that of the OEM battery.

CALENDAR FADE
Even if you never use the battery, it has a limited calendar life. As a general rule, the capacity of an unused battery will reduce to about 80% by the time it has reached two years of age. However, because you are probably using your batteries, rather than keeping them in extended storage, cycle fade (which accompanies battery usage), will be of more interest to us.

CYCLE FADE
A battery's charge retention steadily declines through successive usage cycles over a period of months or years. One whole cycle refers to one charge period plus the following discharge period. The typical test condition is fully charging at 0.5C to a voltage of 8.4V, and then, discharging at 0.5C to a voltage of 6.0V. The cycle life is the number of cycles which can be made before the discharge falls below a set percentage of the rated capacity. A reasonable expectation (for mirrorless camera batteries), would be about 80% capacity after 300 cycles, and 70% capacity by 500 cycles.

It is difficult to assign a time-frame to cycle referenced usage, since this will differ according to the particular photographer using the battery. Fujifilm states that the NP-W126S battery should be good for at least 300 cycles. On the basis of this 300 cycle expectation, if you charged and ran down your battery every day for six days of every week, the battery would barely last one year, before hitting the 80% mark. However, a photographer with such heavy battery usage, is likely to have more than one battery, (with some batteries being charged while others are in use), so that in practice, you may still find that it takes more than 2 years for an individual battery to reach 300 cycles.

The 300 cycle specification does not mean that at 300 cycles, the battery is "dead"; rather, it means that by 300 cycles, because the battery only retains 80% of its original capacity, it may no longer be performing up to the photographer's expectations. For example, on a shoot that could normally be completed on one fully charged battery, you may now have to do a battery change before the end of the shoot, if the battery is showing signs of cycle-fade.

BENCHMARK
As a service life benchmark, an OEM Fujifilm battery can be expected to give four or five years of service. About two years of primary service (top capacity and performance, suitable for professional needs), and about two to three years of secondary service (declining, but still good, capacity and performance, suitable for more casual photography, or for back-up use). The service life has effectively ended when the battery gives an unacceptably small number of shots, or it just won't hold a charge. When comparing 3rd Party batteries to OEM, we should frame the comparison within the context of the four to five year lifespan of the OEM batteries.

DELIBERATION
Because battery ageing takes place over a period of at least months, it is not something that you can assess instantaneously, or within a short period of the purchase time. You mainly get this information from your own extended usage experience, or that of others. Comments such as "I have been using this battery for a while, without any problems", are unfortunately, so imprecise as to be virtually useless. More objective feedback with reliable numbers (such as months of service, charges per month, and typical number of shots per charge), from other battery users (either colleagues, or via on-line forums), is invaluable in making a pre-purchase assessment. Again, the question is whether the 3rd Party battery can equal (or perhaps even better) the long service life of the Fujifilm OEM battery.

[ 9 ] CONTROL CODES

Control codes (or production codes) are an important part of battery manufacturing quality assurance. Although there may be codes on internal components of the battery (and therefore, not visible to the user), the codes of interest to the user, are any codes marked on the case of the assembled battery.

These sequences allow the manufacturer to track such details as a battery's date of production, production batch, production line, region of destination, or other pertinent information. If a battery is found to be faulty, with a systemic fault that may affect other batteries of the same production batch, these codes are necessary to be able to distinguish affected batteries from the rest of the production cohort.

RECALLS AND ADVISORY NOTICES
Control codes allow after sales follow up, in cases where a product batch has been found subject to quality issues. These do happen. In February of 2012, Nikon initiated a voluntary replacement scheme, for specific batches of their EN-EL15 batteries, due to the possibility of the the battery overheating, and the exterior casing becoming deformed. Such a replacement scheme is only possible, because batteries from the affected production batches can be identified, by way of their lot numbers.

PRODUCTION DATE
A cheap battery may turn out to effectively be an expensive battery, if you find that you purchased stock that is several years old. Even though it has never been used, it may now be past its prime, due to calendar fade. Lithium-ion batteries are at their best for about two years, post manufacture. After that, a decline in performance starts to become apparent. With many 3rd Party batteries, their age since date of production is generally not discoverable, and we have to make assumptions about age based on their purchase date. A feature of the Fujifilm OEM batteries is that their production date can be precisely determined.

This is useful, not only for projecting future performance expectation, but also for avoiding overly-old batteries at time of purchase. (Taking into account distribution and logistics matters, up to several months past the production date would seem an acceptable age for a "fresh" battery).

DELIBERATION
Control codes can contribute to our level of confidence in the battery, and as such, can deliver a user-experience type advantage. It affects how you feel about your new battery acquisition in terms of confident expectation that this is a quality battery, with a probable long service life. If it is important to you to ensure that newly purchased batteries are as fresh as possible, and if you can inspect the battery before purchase, OEM batteries, because they can be accurately dated, may have an advantage. Without the ability to date the battery, 3rd Party batteries may have a degree of chance attached to their purchase, especially if the vendor has a low or unknown turnover rate.

[ 10 ] WARRANTY

There are two different warranty issues. One is the warranty on the battery. For the OEM battery, this may only be several (maybe 3) months, depending on your regional Fujifilm office. Among the 3rd party providers, you can find a few that offer a clearly spelled out warranty (in one case, 3 years). But for most of the 3rd Party providers (particularly unbranded, or little know brand batteries), there may be virtually no warranty. The battery's vendor might replace an early failure battery, but mainly as a matter of goodwill, and to preserve good feedback.

CAMERA WARRANTY
The other warranty issue is to do with how using a particular battery could affect the warranty on the camera. If a camera, still under warranty, was damaged due to a defective battery, the camera company would rightly be concerned with the question of whether the battery was an OEM or a 3rd Party battery. Firstly, if the battery was the cause of the damage, the responsibility for the damage should lie with the battery manufacturer, who would not be the camera company, in the case of a 3rd Party battery. Secondly, the camera company typically abnegates responsibility in cases of "failure to follow operating instructions", including the instruction not to use any batteries other than the OEM battery.

For some people, buying an OEM battery, is like paying extra to get insurance, so that they won't have to cover their own repair costs if a defective battery induced problem should occur, while the camera is under warranty.

EXPIRY OF WARRANTY
The warranty issue could be considered a short term, and a transitory issue. Eventually, the warranty on the camera expires, and It could be argued that, if the camera is out of warranty, then the warranty issue is not relevant. This would generally be considered a reasonable position to take. However, if you up-grade your camera regularly, then long term considerations can make this situation a little more complex.

BATTERIES CAN SPAN CAMERA GENERATIONS
Of course, a new camera comes with a new OEM battery, so there is no problem there. However, many people require more than one battery for their camera. As an example, for my X-T3 camera, I currently have 5 batteries (all of them OEM): one in the body, two in the grip, and two spares. One was supplied with the camera, but the other four, still working well, were taken from my older X-T2. The point is, batteries can span camera generations. So even when the X-T2 went out of warranty, there was an advantage in purchasing OEM batteries as spares, because they later ended up being used in a new "under warranty" camera again (the X-T3).

INSURANCE
If you are a professional photographer, who has all of your photographic gear insured, you can effectively bypass the warranty issue, if your policy is comprehensive enough to cover battery failure, or battery instigated camera damage.

DELIBERATION
Statistically, most people will never have to make a warranty claim on their Fuji-X camera. Once the camera is out of warranty, this may not be an issue at all. You may be willing to take the risk of using a battery that, in the perhaps unlikely event that it damages your camera, could lead to you having to pay the repair (or replacement) costs. The probability of this not happening, is on your side. You may consider this an area where, although it's nice to have the security, you are willing to save some money, by taking the chance that this issue does not ultimately eventuate.

[ 11 ] RELIABILITY

Reliability refers to a high level of confidence in a battery, both in terms of safety, and general operability. Battery reliability may be of critical importance to professional photographers, as well as other photographers who are working at a high level of camera expectation, or high rate of workflow. But it can also be relevant to any photographer who would like to have a trouble-free photographic experience. Unreliability can manifest as safety problems or service problems.

SAFETY RELIABILITY
Safety reliability is concerned with the battery's ability to handle various types of accidental abuse. Assurance testing typically covers electrical, thermal, and mechanical types of abuse.

When subjected to these types of abuse, the battery should have a high level of resistance to combustion or explosion, or if the battery does combust/explode, the effect should be relatively contained (ie, not releasing flaming particles, or high velocity projectile fragments).

COMPLIANCE
Certification and conformity guarantee that the battery type has been tested up to appropriate standards. The Fujifilm OEM batteries comply with applicable standards for user replaceable batteries. The current battery displays 5 compliance symbols.

The battery may also be compliant with other standards, which do not mandate display of a symbol or marking (for example, transport of dangerous goods by air, under UN/DOT 38.3). Internally, the OEM battery shows compliance with relevant standards. For instance, the protection circuit board states compliance with UL 94V-0 Flammability Test, as well as carrying the UL Recognized Component mark ("backward R" U).

3rd party batteries frequently carry only the CE marking (which can be self-assessed), or no compliance markings at all.

FAKE CERTIFICATION OR CONFORMITY
Sometimes the certification or conformity markings (particularly the CE mark), of 3rd Party batteries are fake. An un-branded battery could not achieve proper CE conformity, because CE compliance must always be traceable, and someone must ultimately be accountable. Traceability facilitates market surveillance by the regulating authority, and makes the identification required for enforced withdrawals and recalls, possible. For CE conformity, the manufacturer needs to hold documentation, including a Declaration of Conformity (DoC), as well as a Technical File, which is a dossier fully documenting the evidence relating to the product's compliance with the applicable safety standards. Obviously, such documentation (even if it does exist), is not open to scrutiny by the regulating authority, if the manufacturer is anonymous, or cannot be contacted or located. The product is also required to bear a batch, type, serial, or model number, for identification. The following battery lacks the basic features required for traceability. (In this case, it doesn't even state the country of origin).

Other batteries give away their sham compliance by using an incorrect form of the CE mark. The true CE mark has a significant space between the two letters, due to the overlap of the two "construction" circles, underlying the design:

However, on the following 3rd Party battery, the spacing is reduced, and the middle bar of the E letter, is longer than it should be.

This look-alike symbol is sometimes referred to as the "China Export" mark. In terms of indicating conformity to safety standards, it has no real meaning.

SERVICE RELIABILITY
Battery reliability is not only concerned with safety, but also with the ability to complete the task at hand, without undue delays (such as unscheduled battery changes), erratic equipment behaviour, or data losses. Service problems can be: low shot count, "flat-without-warning", high self discharge, short lifetime, and irrecoverable sudden battery failure. Battery failure (including full depletion without sufficient warning), can result in missing a key shot, or sudden stopping of a video sequence without the proper termination and shut-down procedure, resulting in possible data corruption, or even complete loss of the video file. Furthermore, there may be unforeseen events, which will push the camera and battery to the limits of endurance, and we would like to have confidence that the battery can handle these situations.

RELIABILITY OF THE PHOTOGRAPHER
For some professional photographers, it may be the case that use of OEM batteries is effectively mandatory. For instance, the risk of batteries failing during a shoot with no possibility of re-shoots or second chances (the ceremony part of a wedding shoot, or fast paced sporting events photography), could make the selection of battery type virtually non-discretionary. Your clients have a reasonable expectation that you have exercised due diligence in ensuring that their photographic brief can be fulfilled. Missing a key shot, because a battery, which was chosen on the basis of its lower cost, failed without warning, falls below the best standards of professionalism. If you happen to live in an ultra-litigious society, the fact of having used your equipment according to the directions of the camera's manufacturer (including, using the specified battery), may form an important part of your defense, in case of a law suit brought against you, over a photographic brief marred by misadventure, either through failure to capture non-repeatable moments and events, or through accident or injury due to battery initiated fire or explosion. For professional photography, a higher price paid for OEM batteries might just be considered one of the costs of running the business.

TENDERING FOR CONTRACTS
Some professional photographers have experienced that when tendering for the contract of a video or photographic project from a government department, or a major corporate entity, contractual expectations for the tender may include submitting copies of recently developed risk assessments that are relevant to the tender, as well as evidence that equipment is maintained in accordance with manufacturer/legislative requirements. Strictly speaking, equipment needing to meet compliance with safety standards, would also include user replaceable lithium-ion batteries, and it may be that only the OEM battery is able to meet this requirement.

DELIBERATION
When exploring the critique of reliability, there are issues that are very significant for professional and highly specialised amateur photographers, that might not hold the same significance for the casual, recreational photographer. If we think of confidence in our equipment as, "having a good feeling that something bad won't happen", we have to recognise that the "something bad" has a different significance for the high-level pro (where a botched brief or battery-caused injury, could mean lawsuits, loss of reputation, or even bankruptcy), and for the specialist amateur (where it could mean the failure of a long planned and expensive project or expedition), compared to what it means to the casual photographer (where a missed shot may only be a transitory annoyance, and simply written off as bad luck). How important this issue is to you, only you can decide. Once again, you might ask, is the benefit of a high level confidence in equipment reliability, worth the extra battery cost?

[ 12 ] ULTIMATE VALUE

When I say "ultimate value", what I mean, expressed in a few more words, is "Ultimately, it all comes down to the amount of user relevant Value (not necessarily monetary) delivered by the battery". At the very beginning, we looked at battery price, and the differences between OEM and 3rd Party batteries were stark. In order to justify the higher cost, the OEM battery had better deliver a lot of benefits to the battery user.

This is how I have chosen to present summaries for various battery types, in a very visual way, in order to assist "getting your head around" a very complex analysis. Your methods and conclusions may differ considerably. For a final analysis, I have brought together all of the criteria in a single chart, and further grouped the criteria into the categories of PRICE & VALUE, CAPABILITY & PERSISTENCE, and SAFETY & CONFIDENCE. This represents the personal way that I chose, to compile information about different batteries, for the purpose of producing an overview. You may have a method that suits your needs and preferences better. Please note that the selected criteria are by no means comprehensive, and the individual battery user may be in circumstances where other criteria (for instance, cold climate battery performance), may also be very important.

For the PRICE critique, a lower price scores higher, and its line has the related critique of VALUE at the other end. They are the two poles of the consideration: "How much does it cost, but also, how much do I get, for what I pay?" (For our purposes, the VALUE critique has simply been based on an aggregate of the capability, persistence, safety, and confidence scores).

Another line joins the related critiques of CAPABILITY and PERSISTENCE. Capability simply means the ability of the battery to power the camera, for an acceptable period of time, or for an acceptable number of shots. It means the battery has the capacity required by the photographer, and can deliver the performance required by the camera. Persistence means that the capability that we experience now, is able to be sustained into the future, both short term (low self discharge), and long term (long battery service life).

The third line joins SAFETY and CONFIDENCE. Safety should be relatively self-explanatory. But as well as its practical implications, working within a safe system also affects how we feel, while we work. Together with the "confidence" given by using a battery which is specified for the system, (feelings of) Safety and Confidence, operate in the "affective domain". They can allow us to work with a positive and self assured attitude, rather than from a position of underlying apprehension of possible adversity. (For example "I would like to charge this battery in-camera, but I'm afraid that it might swell and get stuck"). In extreme cases, it could make the difference between photography being a fulfilling endeavour, or a stressful task.

This circular arrangement of the criteria will form the basis for a type of graph, variously known as a spider(-web) graph, or as a radar graph. The use of this graphic display is only intended as a tool for exploring the multivariate nature of battery choice, and is not intended as the graphic proof of a universal best choice battery. First, let's look at:

THE PERFECT BATTERY
This battery (which unfortunately does not exist in reality) achieves top scores on all measures, and cannot be surpassed. It is presented here, simply as an ideal to aspire to.

Apart from its perfect scores, the battery's graphic profile is characterised by a "roundness", showing that the battery addresses all relevant areas of critique, rather than concentrating on some and neglecting others. In terms of a graphic profile, this is the type of result that we would like to achieve.

THE FUJIFILM OEM BATTERY
This battery scores very well on all areas of critique, apart from price. Note that it never achieves full possible scores, in recognition that, in reality, there is always room for further development and improvement.

This would be a very well rounded battery, if not for the high (low scoring) price. The high price is testimony that research and development, materials selection, quality management, and achieving safety accreditations, all come at a monetary cost. You pay a lot, but you do get a lot for it. The question is whether some of those benefits (which you have paid for) are superfluous to you personal photographic needs (for instance, warranty implications, and accurate battery level display). It could be claimed that the price is out of proportion to the value, and this is reflected in the distortion of the shaded area of the chart, deviating from the roundness of the "perfect battery". What do you think?

TOP-TIER 3rd PARTY BATTERY
These batteries are in the highest price-group of the 3rd Party batteries, and are generally highly respected. It is rare to hear bad reports about them. (Note that this group excludes those batteries that have a reputation for swelling, or an overstated capacity).

Safety has been marked down because the battery's lack of thermistor is a compromising factor whenever the battery is charged in a Fuji charger, or charged in-camera. The capacity and persistence, which are the most obvious day-to-day criteria for battery worth, are good. For the price, we get a well rounded battery, and a good solid performer.

LOW COST 3rd PARTY BATTERY
These batteries deliver decent short term operability, at a very competitive price. However, over a longer time frame, their deficiencies begin to show. (Note that a lower capability score may simply indicate smaller internal cells, rather than being a reflection on the cell quality).

Over time, high self discharge, swelling, high cycle fade, and ultimately, short service life may become apparent. The low price is achieved partly through cutting production costs, which is seen along the SAFETY-CONFIDENCE line. Safety can be compromised by, for example, using soldering for terminal connections, rather than welding, and by using adhesive tape as an insulating cell-separator, rather than the specially designed cell-separator of the OEM battery. The graphic profile of this battery type is unbalanced, and very "un-rounded". And yet, for some photographers, this battery suits their photographic needs, without incurring the extra costs of "benefits" that may produce little "real" difference for them. If you have a few of these batteries in your bag, then if one fails or misbehaves, just swap in one of the other back-up batteries. This is a practical type of reliability, achieved at a low cost.

DELIBERATION
I have tried, throughout this exploration of battery issues, to present mainly evidence based information, and avoid too much conjectural discussion. Yet, I am very aware that my analysis of a battery type's worth, may differ from that of another experienced photographer, and I respect the value of the differing viewpoints. I hope that I have given sufficient technical material for the reader to arrive at their own informed judgement about which battery type (OEM or 3rd Party) represents the best choice for their own personal photographic style and needs. There is no universally correct answer, but there is an individually appropriate one.

THE DECISION

That bell marks the end of the final round. You 've watched the battle. You've witnessed the blows. Now it's time to make YOUR decision. Will it be the Fujifilm Champ, or the 3rd Party Contender?

And the winner is . . .

Thanks for reading -

THE GREAT BATTERY BRAWL

[ Last updated: 25 July 2019 ]

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Fuji NP-W235 Battery

… Making sense of the numbers

‚‚The NP-W235 is the new battery for the recently released Fujifilm X-T4 camera. The following compilation of battery characteristics is taken from "nameplate" specifications (on the battery label), and published specifications (mainly X-T4 Owner's Manual), as well as some independently derived specifications. Explanations of the interpretation and significance of the various specifications are also given. For convenience, key points are noted for most sections.

Given that the new battery's double-curved face is not very suitable for printing, most information is contained on the under-surface of the battery (unlike the NP-W126S battery which was able to use both front and back surfaces). The NP-W235's under-surface displays specifications and safety warnings, and some standards compliance information, with different sections in English, Japanese, Korean, French, and Chinese. Because of limited space, only the safety warnings tend to be duplicated in the different languages. Other standards compliance symbols are impressed on the top and bottom ends of the battery.

CONTENTS

[ 1 ] Battery Name
[ 2 ] Component Cells
[ 3 ] Capacity
[ 4 ] Voltage
[ 5 ] Nominal Energy
[ 6 ] Dimensions
[ 7 ] Volume
[ 8 ] Weight
[ 9 ] Volumetric Energy Density
[ 10 ] Gravimetric Energy Density
[ 11 ] Charging Temperature Protocols
[ 12 ] Operating Temperatures
[ 13 ] Production Date
[ 14 ] Summary
Appendices

[ 1 ] BATTERY NAME

Fujifilm have continued to follow their naming scheme for multi-cell battery packs, where the battery model number is derived from the battery's capacity. Some older battery models do not conform to this scheme.

The apparent discrepancy between the NP-W235's derived 2350mAh capacity specification, and the 2200mAh actually printed on the battery, will be explained below (refer: Section [ 3 ] CAPACITY ).

[ 2 ] COMPONENT CELLS

The B-profile (or "B" cross-section) of the NP-W235 battery is an immediate clue to what shape cells are inside. In contrast, previous X-series and GFX-series batteries have had rectangular profiles/cross-sections, indicating rectangular-prism shaped (admittedly, with rounded edges) internal cells.

However, the battery also carries a standardised alpha-numeric descriptor string (2INR19/50), which indicates the internal composition of the battery pack, by cell type and size. Note that the descriptor string makes no reference to capacity.

You can find this same 2INR19/50 alpha-numeric string on similarly sized batteries from other camera makers, such as Canon's EP-L6, Nikon's EN-EL15, and Sony's NP-FZ100, for example, although older batteries may not carry this descriptor string.

The NP-W235 battery (like its NP-W126S and NP-T125 siblings), is manufactured by Panasonic Energy, in its Wuxi, China, plant.

The internal cells are most likely Panasonic's NCR18500 cells (model variant still to be identified), which fit the descriptor string. A retrieved copy of the data sheet for this cell, quoted a Minimum Capacity of 1900 mAh, but this data sheet (NNP Series, NCR18500, 2010B-1) was from February 2010. It is not unreasonable to expect the current model variant to be in the 2200 mAh capacity range, after a further 10 years of development.

[ 3 ] CAPACITY

Capacity indicates the battery's capability for sustained transfer of electrical charge. It specifies current per period of time, as milli-Amp hours (mAh). Past models of Fujifilm batteries commonly stated two different capacity specifications on the battery: a Typical Capacity, and a Minimum Capacity.

With the NP-W235 battery, Fujifilm have used a revised terminology for stating capacity (when using English language), which is to specify a Nominal Capacity and a Rating Capacity. These two specifications can be found in the X-T4 Owner's Manual (English language PDF, page 338). We presume that this change only represents a difference in the naming of the specifications, but not in the underlying specifications that are indicated. The terminology differences are contrasted in the following table:

The NP-W235 battery only carries one printed capacity specification, 2200mAh, which is the Rating Capacity. The capacity value which would be determined from the battery name (a value of 2350mAh on the basis of the “235” in the name), is the Nominal Capacity. Note that the label's second occurrence of the 2200mAh value is preceded by the Chinese characters 额定容量 which generally have the meanings indicated in the Term (2) column of the table below.

Term (2) is commonly rendered as "Nominal". (Try copy-and-pasting "translate 额定容量" into your browser, and check the various results). However Fujifilm's NP-W235 English language usage, now renders Term (1) as "Nominal" (instead of "Typical"). The current Fujifilm usage essentially conflates the terms "Nominal" and "Typical". Because of this, we must be careful when making specification comparisons.

The practical difference between the two Capacity specifications (Rating or Nominal), is largely related to intention. The Rating Capacity (or Rated Capacity) can be seen as a more formal expression of the Capacity, and might be used where the intention is to specify a reference class, or to indicate conformity, in situations pertaining to regulations (examples of such would be, safety, statutory, or excise contexts). The Rating Capacity is also the proper specification to use whenever a capacity is required for the determination of other specifications (for example, to determine Energy Capacity). In contrast, the (now called) Nominal Capacity, (formerly referred to as the Typical Capacity), is appropriate for contexts where the intention is to inform user expectation. This capacity value can reflect optimal results obtainable under ideal usage conditions.

The reason Nominal Capacity and Rating Capacity differ in their values, is because they were determined under different measurement conditions. Controlled measurement conditions include discharge rate, discharge termination voltage, and reference temperature. Changes to any of these conditions will affect the outcome of the Capacity test. Recent Fujifilm batteries (such as the NP-W126 class batteries) used different reference temperatures for the Typical and Rated Capacity measurements of their internal cells, with 25°C being used for determining Typical Capacity, and with 20°C being used to determine the Rated Capacity.

Within the standard operational range, the measured battery capacity will be positively affected by increased ambient temperature, and negatively affected by increased discharge rate. This effect is known as capacity offset.

Differences due to testing conditions (in this case, the reference temperature) adequately account for the capacity variations when comparing Nominal Capacity and Rating Capacity values.

However, the main reason for the user to differentiate between Nominal Capacity and Rating Capacity, is to avoid making invalid comparisons between different battery models. For example, make sure that the Typical Capacity of the NP-W126S is compared with the Nominal Capacity of the NP-W235, and that the Minimum Capacity of the NP-W126S is compared with the Rating Capacity of the NP-W235.

[ 4 ] VOLTAGE

Voltage, or electromotive force, is the potential difference that the battery is able to effect across an energised circuit. There are two voltages printed on the NP-W235 battery: a Nominal Voltage, and a Maximum (or Charging) Voltage. The Nominal Voltage (7.2 Volts) is followed by the "solid line over dashed line" (Unicode symbol U+2393), which simply indicates that it is a Direct Current voltage. This 7.2 Volts is the expected Nominal Voltage for a twin cell Lithium-ion battery. The Maximum Voltage (8.4 Volts) is preceded by the Chinese characters 充电限制电压 meaning "Charging Voltage Limit".

Although Fujifilm does not specify a Minimum Voltage, this voltage is implied from the Maximum and Nominal Voltages, since (by definition) the Nominal Voltage lies halfway between the Maximum and Minimum Voltages. Because the battery uses two cells connected in series, the battery voltage specifications are double those of a single cell.

Battery voltage is not a constant, but continuously varies according to the battery's state of charge. Stating a Nominal Voltage is a way of attributing a virtual "fixed" voltage to the battery.

Note that, because the relationship between the battery's voltage and capacity, is non-linear, the Nominal Voltage does not necessarily coincide with the battery's 50% capacity point.

[ 5 ] NOMINAL ENERGY

Nominal Energy, or Energy Capacity, is the rating measure for the amount of energy that is stored in the battery. The Nominal Energy of the NP-W235 battery is 16Wh (Watt hours). It is determined by multiplying the Rating Capacity in Amp-hours by the Nominal Voltage of the battery.

Significantly, the NP-W235's Nominal Energy is even higher than that of the GFX system's NP-T125 (14Wh) battery. The big increase that came with the NP-T125 battery, was its ability to power a higher voltage (10.8 Volt) system.

The NP-T125 (GFX series battery) has been shown for comparison, while noting that the stated voltage and capacity do not produce exactly 14Wh. There is a another possibility, which is, that the NP-T125's Nominal Energy is actually 13.3Wh, and has been rounded up to 14Wh. This is reasonable if the specification is understood in the sense of "The battery's nominal energy does not exceed 14Wh", an appropriate assertion when set in a safety assessment context.

The International Air Transport Association (IATA) safety regulations, require lithium-ion batteries to be marked with the battery's Watt-hour rating on the outside case. The Watt-hour rating is the measure by which lithium-ion batteries are regulated. Batteries, power banks, and devices with batteries inside, are assigned to different risk categories on the basis of the amount of energy they hold (energy which could be released as heat, fire, or explosion). In this context, 100Wh is the significant threshold for being categorised into a higher, more stringently controlled hazard class. The NP-W235 battery (at 16Wh) falls well below this threshold.

When comparing different batteries solely on the basis of mAh Capacity, differing Voltages can be a confounding factor, reducing the validity of the comparison. Nominal Energy is a better specification for comparing the ability of batteries to drive a system, because it takes into account the Nominal Voltage of the battery, as well as the battery's Coulombic Capacity.

[ 6 ] DIMENSIONS

The battery's Dimensions specify its maximum extensions along various axes. The following figures are from the published dimensions of the NP-W235 battery. Of course, whether you consider the longest dimension to be a Height or a Length measurement, depends on the observational orientation of the battery.

This information, however, is of limited usefulness, because of the complexity of the battery's shape, when compared to that of a simple prismatic shaped battery such as the NP-W126S. For this reason, we would like to also take a closer look at the battery's Volume.

[ 7 ] VOLUME

The battery's Volume is not specified by Fujifilm, so it has been derived independently. Volume indicates the amount of space appropriated by the battery. However, with respect to total camera size, the idea that "smaller is always better" may be overly-simplistic, when we consider that a more "substantial" camera, can contribute to a more satisfying (and more sustainable) hand fit, and feel. Knowing the battery's Volume is advantageous, because it can be used to determine Volumetric Energy Density. (refer: Section [ 9 ] VOLUMETRIC ENERGY DENSITY ).

Although the Volume can be measured by displacement methods, I have used a graphical method to estimate the battery's Volume. In contrast to a prismatic battery pack, where it is a simple matter of multiplying its three dimensions, the Volume of a battery pack with complex shape details can be tedious to derive based on linear dimensions. However, if we ignore micro-details (deeming them trivial, in terms of their contribution to the total volume), and look only at the larger-scale shape of the battery, the Volume assessment process can be simplified considerably. If we can determine a cross-sectional area, it is only necessary to multiply it by the height (or length, depending on how you look at it) in order to derive a good approximation of the battery's Volume.

A distortion-free photographic image of the end of the battery, has been used as a surrogate for this cross-sectional shape. Applying a grid method for estimating the area of an irregular shape, a scaled 2 x 2 millimetre grid was overlaid, so that each grid cell represented 4 square mm.

The grid cells were each assessed as to whether they enclosed 0, 1, 2, 3, or 4 square mm (rounded to the nearest square mm) of the shape. Critical squares could be further divided in four equal squares or four equal triangles, as appropriate, in order to facilitate the assessment. In this way, the area of the image shape was estimated.

Based on this grid method, the cross-sectional area is approximately 776 square mm (1.2 square inches). Multiplying this area measurement by the length of the dimension perpendicular to it (52.3mm), gives a volume of approximately 40585 mm³.

The Volume estimate of 40585 mm³, is only 87% of the rectangular-prismatic volume (46386 mm³) which would be obtained by simply multiplying together the Height, Width, and Thickness.

With irregular shape profiles (such as this B-profile), space savings (due to contoured "form fitting" surfaces, for example), may not be able to be fully realised. For instance, the available space may be in locations where, in practical terms, it is of little use. Furthermore, to the extent that a camera's battery chamber might still take a basically rectangular shape, the reduced (due to contours) volume of the battery might be effectively negated. However, apparent "wastage" of potential free space (as air spaces or voids), may still be contributing to design efficiency in other ways, such as heat transfer control. For these reasons, the battery's space demands (how much bearing it has on the size of the camera), probably fall intermediate between the minimum footprint (based on the contoured shape), and the maximum footprint (based on the extreme dimensions of the virtual rectangular-prism shape).

Compared to the NP-W126S battery, the NP-W235 increases Rating Capacity at the cost of some "loss of compactness". Importantly, the Capacity gain offsets and exceeds the loss. Note that the NP-W235's true (not prismatic) Volume was used.

[ 8 ] WEIGHT

Battery weight contributes to the required long term effort involved in supporting the camera during use. However, the idea that "lighter is always better" is possibly overly-simplistic, when we consider that the extra inertia of an appropriately "weighty" camera, can contribute to stability in hand-held usage. The NP-W235 battery weight (from published specifications) is 79g, or 2.8oz. The (presumed) 18500 cells should weigh approximately 34g each, with the balance of the battery weight (about 11g) due to battery case and circuit board. For comparison, the NP-W126S battery weighed 47g total, with each internal cell weighing 20.3g, and the balance of the battery weight (about 6.4g) being due to the battery case, internal separator, and circuit board.

Compared to the NP-W126S battery, the NP-W235 increases Rating Capacity at the cost of some "loss of lightness". Importantly, the Capacity gain offsets and exceeds the loss.

[ 9 ] VOLUMETRIC ENERGY DENSITY

The battery's Volumetric Energy Density is not specified by Fujifilm, so it has been derived independently. The Volumetric Energy Density reflects the efficiency impact of the battery's spatial footprint on the camera size. It is specified in Watt-hours per litre (Wh/l). Provision of increased battery power, typically comes at the cost of increased camera size. If a new battery model has an increased Volumetric Energy Density value, that increase tends to justify any growth in camera size (due to larger battery).

The Volumetric Energy Density is calculated by dividing the Nominal Energy of the battery pack by its Volume. (For reference, one cubic millimetre is 1.0E-6 Liters). It is worth remembering that the total increase in camera size from the X-T3 to the X-T4, is not only due to increased battery size, but also to the inclusion of the new IBIS mechanism.

[ 10 ] GRAVIMETRIC ENERGY DENSITY

The battery's Gravimetric Energy Density is not specified by Fujifilm, so it has been derived independently. The Gravimetric Energy Density reflects the efficiency impact of the battery's mass on the total weight of the camera. It is specified in Watt hours per kilogram (Wh/kg). The provision of increased battery power, typically comes at the cost of increased camera weight. If a new battery model has an increased Gravimetric Energy Density value, that increase tends to justify any rise in camera weight (due to heavier battery).

The Gravimetric Energy Density is calculated by dividing the Nominal Energy of the battery pack by its Weight. It is worth remembering that the total increase in camera weight from the X-T3 to the X-T4, is not only due to increased battery weight, but also to the inclusion of the new IBIS mechanism.

**_[ 11 ] CHARGING TEMPERATURE PROTOCOLS

_**

In order to avoid cell degradation during the charging process, the Fujifilm charging systems (both in-camera and external), switch to different charge rates for different temperature ranges, or even suspend charging if the temperature is outside the allowable range. I will refer to this behaviour as implementing Charging Temperature Protocols. These Protocols are required by the battery, but implemented by the charging device. As an example of how this works, when charging the NP-W126S battery in the BC-W126S charger, if the thermistor resistance (read from the T terminal of the battery) reaches 27 kΩ (kilo-Ohms) or higher, it indicates that the (inversely related) battery temperature is 10°C (50°F) or lower. This temperature is too low for optimal charging, and triggers a charge current reduction from the normal 720 mA (a rate of 0.6 C), to the low-temperature charge current of 420 mA (a rate 0.35 C). These numbers were verified experimentally. The low rate is specified by Panasonic's data sheet for the NP-W126S's internal cells (NCA673440), where it states "At temperatures below 10°C, charge at a 0.35C rate". We expect the charging of the NP-W235 battery to be managed in the same way. The X-T4 Owner's Manual (English PDF, page 309) states that "Charging times will increase at ambient temperatures below +10°C (+50°F) or above +35°C (+95°F)". The reason for the increased charging times, is the reduction in charging rate, for these low and high temperature ranges.

In the past, third-party chargers have not replicated this temperature referenced behaviour, so we wonder, in the near future when we foresee third-party "NP-W235" batteries and chargers becoming available, whether they will observe these temperature based Charging Protocols. Whatever the case, the extent to which third party options are able to implement strategies to avoid cell degradation, will be of importance in determining the suitability, safety, and wisdom of choosing such options.

[ 12 ] OPERATING TEMPERATURES

There is an expectation that Lithium-ion powered digital cameras, like the X-T4, will be operated in a wide range of environmental temperatures. Within this range, the Lithium-ion battery should be able to perform efficiently and safely. The X-T4 Owner's Manual (English language PDF, page 338) specifies the battery's Operating Temperature range as 0°C to +40°C. However, this specification is too conservative in the low temperature range, where Lithium-ion batteries are able to operate at temperatures significantly below freezing (Note, this is for operation, that is, discharge, not charging ). If we consider the NP-W126S battery (also specified as 0°C to +40°C by Fujifilm), we find that Panasonic's data sheet for the internal cells, states a discharge temperature range of -20°C to +60°C. We would expect a similar range for the NP-W234 battery. The upper limit of this range aligns with the maximum temperature of +60°C printed on the battery.

Adding to the perplexity of this matter, on page 337 of the X-T4 manual, under "Power supply/other > Operating Conditions", a temperature range of -10°C to +40°C (+14°F to +104°F) is stated. I would suggest that the 0°C to +40°C range is a recommended Operational Temperature range (and possibly an amalgamation of the safe discharge temperature range, and the safe charging temperature range), while the -20°C to +60°C is the Absolute Environmental Temperature range, for the battery. In general, Lithium-ion batteries can be discharged well below 0°C (although the available capacity will be reduced). When Lithium-ion batteries operate at very low temperature, a typical decrease in efficiency is: while at -10°C the battery can deliver only about two-thirds of its normal capacity, and while at -20°C the battery can deliver only about half of its normal capacity. Although these very low temperatures are not ideal, the batteries can be utilised (but not charged) at these temperatures, and photographers do successfully use them down to -10°C and lower. Operating Temperature range is a specification area where Fujifilm could make further clarification.

A subset of the environmental temperature range is the Storage Temperature range. The X-T4 Owner's Manual (p. 309) states this range as +15°C to +25°C (+59°F to +77°F). This temperature range is to avoid cell degradation while the battery is not being used for extended periods of time. Although not explicitly stated by Fujifilm, the optimal storage temperature is the lower value in the range, about +15°C (+59°F), and the optimal state of charge during storage, is about 40 - 50%.

[ 13 ] PRODUCTION DATE

Mainly for the purpose of tracking production batches, OEM batteries are typically marked with a production number, which can identify the production lot, and possibly also, the date of production. Production lot information may be required for warranty issues, as well as for product safety notifications and recalls. Some standards, such as Korean Certification, require the production year, month, and lot number, to be provided. The new NP-W235 battery (unlike the NP-W126 series batteries, which required a decode-chart in order to determine the production date), follows the NP-T125 (GFX cameras) practice of clearly displaying the production date on the battery.

The first two digits indicate the year, and the second two indicate the month. Production date is relevant to the user because lithium-ion batteries typically give their best performance within a two year period of the time of production. Knowing the production date can assist in predicting when a performance drop-off is likely to begin, and in devising a replacement plan.

Although the X-T4 camera's "battery age" display function, might make knowing the production date superfluous in terms of battery replacement planning, the production date information can still be a useful unique identifier to distinguish between multiple batteries.

[ 14 ] SUMMARY

The Fujifilm X-T series mirrorless cameras have been renowned for their reduced size and weight when compared to DSLR cameras. With the release of the X-T4 and its bigger battery, there is widespread approval of the longer operation times available, but also some reservations about the effects on camera size and weight due to both the IBIS and the larger battery. The following table compares important properties of the NP-W126S and NP-W235 batteries, which affect performance against size/weight trade-offs.

Compared to the NP-W126S battery, the NP-W235 is more efficient, as is evidenced by its higher Volumetric and Gravimetric Energy Densities. This equates to more power for the package size and weight. The modest down-side costs of increased weight and size, are offset by a significant gain in Capacity, at advantage ratios that could not be achieved by simply designing the new camera to hold two NP-W126S batteries, for example.

This survey did not look at shots-per-charge, or video-capture endurance, since, as a matter of not only battery efficiency but also camera efficiency, such investigations are beyond the stated scope of the present study. However, We look forward to being able to test the new battery, in real world situations, where we expect the results to be different from those of the standard CIPA testing. I hope the present work will give users of the new X-T4 camera, a better appreciation of the NP-W235 battery, and contribute to realistic performance expectations.

APPENDICES

TEXT INFORMATION SOURCES

Fujifilm NP-W235 Operating Instructions: BL00005069-100
(日本語, English, Français, Deutsch, and Español)
and
Fujifilm NP-W235 Istruziono d'uso: BL00005069-300
(Italiano, and Pусский)

Fujifilm Digital Camera X-T4 Owner's Manual: BL00005063-201
(English)

TRANSLATION OF THE JAPANESE SECTION
The Japanese printed sections of the battery label read:

電式バッテリー
Electric battery

富士フイルム株式会社
Fujifilm Corporation

使用後は、リサイクル協力店へ
After use, take to a recycling center.

危 険 :
Danger:

大険・ 発熱、発炎、破裂の原因となるので、火・水中投入、加熱、分解、ショートなどしないこと。
Do not throw into fire / water, heat, disassemble, or short-circuit as this may cause serious injury, heat generation, fire, or rupture.

高温での充電、 使用、放置をしないこと。
Do not charge, use or leave at high temperature.

専用充電器以外で充電しないこと。
Do not charge with any device other than the dedicated charger.

TRANSLATION OF THE CHINESE SECTION
The lower four lines of the battery label (written in Chinese), read:

富士胶片株式会社
Fujifilm Co., Ltd.

锂离子电池组
Lithium-ion battery pack

型避:NP-W235
Type: NP-W235

中国组装
Assembled in China

充志限制电压 :8.4V
Charging voltage limit: 8.4V

额定容量 :2200mAh
Rated capacity: 2200mAh

注意:
Note:

禁止拆解、手击、挤压或投入火中。
Do not disassemble, strike, crush or throw into fire.

请勿置于高温环境中。
Do not place in high temperature environment.

电池浸水后禁止重用!
It is forbidden to reuse the battery after immersion in water!

[Last revised: 18/05/2020]

A NOTE OF CAUTION

The Internet is full of misleading and outright wrong "information". I make every effort to ensure that the information I present is factual, as best I am able to establish. However, there is always the possibility that I have made a mistake, or that my sources are in error. If you are going to use the above information as the basis for important decisions, or use it as a reference source for other informative works, I recommend that you exercise due diligence and seek independent verification of the accuracy of the information presented here.

Thanks for reading . . .

_**Fuji NP-W235 Battery

**_

_If you would like to support me in continuing to produce high quality reference material, like this, please consider donating, maybe even the cost of a coffee.
Ciao!
_

All images © 2020 Dom Varney

Photographic images on this page are licensed under a

Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

#measurementsdeterminations #phototips #technologychoices #2350mah #2inr1950 #battery #capacity #fujifilm #npw126s #npw235 #xt4

Fuji NP-W235 Battery

… Making sense of the numbers

‚‚The NP-W235 is the new battery for the recently released Fujifilm X-T4 camera. The following compilation of battery characteristics is taken from "nameplate" specifications (on the battery label), and published specifications (mainly X-T4 Owner's Manual), as well as some independently derived specifications. Explanations of the interpretation and significance of the various specifications are also given. For convenience, key points are noted for most sections.

Given that the new battery's double-curved face is not very suitable for printing, most information is contained on the under-surface of the battery (unlike the NP-W126S battery which was able to use both front and back surfaces). The NP-W235's under-surface displays specifications and safety warnings, and some standards compliance information, with different sections in English, Japanese, Korean, French, and Chinese. Because of limited space, only the safety warnings tend to be duplicated in the different languages. Other standards compliance symbols are impressed on the top and bottom ends of the battery.

CONTENTS

[ 1 ] Battery Name
[ 2 ] Component Cells
[ 3 ] Capacity
[ 4 ] Voltage
[ 5 ] Nominal Energy
[ 6 ] Dimensions
[ 7 ] Volume
[ 8 ] Weight
[ 9 ] Volumetric Energy Density
[ 10 ] Gravimetric Energy Density
[ 11 ] Charging Temperature Protocols
[ 12 ] Operating Temperatures
[ 13 ] Production Date
[ 14 ] Summary
Appendices

[ 1 ] BATTERY NAME

Fujifilm have continued to follow their naming scheme for multi-cell battery packs, where the battery model number is derived from the battery's capacity. Some older battery models do not conform to this scheme.

The apparent discrepancy between the NP-W235's derived 2350mAh capacity specification, and the 2200mAh actually printed on the battery, will be explained below (refer: Section [ 3 ] CAPACITY ).

[ 2 ] COMPONENT CELLS

The B-profile (or "B" cross-section) of the NP-W235 battery is an immediate clue to what shape cells are inside. In contrast, previous X-series and GFX-series batteries have had rectangular profiles/cross-sections, indicating rectangular-prism shaped (admittedly, with rounded edges) internal cells.

However, the battery also carries a standardised alpha-numeric descriptor string (2INR19/50), which indicates the internal composition of the battery pack, by cell type and size. Note that the descriptor string makes no reference to capacity.

You can find this same 2INR19/50 alpha-numeric string on similarly sized batteries from other camera makers, such as Canon's EP-L6, Nikon's EN-EL15, and Sony's NP-FZ100, for example, although older batteries may not carry this descriptor string.

The NP-W235 battery (like its NP-W126S and NP-T125 siblings), is manufactured by Panasonic Energy, in its Wuxi, China, plant.

The internal cells are most likely Panasonic's NCR18500 cells (model variant still to be identified), which fit the descriptor string. A retrieved copy of the data sheet for this cell, quoted a Minimum Capacity of 1900 mAh, but this data sheet (NNP Series, NCR18500, 2010B-1) was from February 2010. It is not unreasonable to expect the current model variant to be in the 2200 mAh capacity range, after a further 10 years of development.

[ 3 ] CAPACITY

Capacity indicates the battery's capability for sustained transfer of electrical charge. It specifies current per period of time, as milli-Amp hours (mAh). Past models of Fujifilm batteries commonly stated two different capacity specifications on the battery: a Typical Capacity, and a Minimum Capacity.

With the NP-W235 battery, Fujifilm have used a revised terminology for stating capacity (when using English language), which is to specify a Nominal Capacity and a Rating Capacity. These two specifications can be found in the X-T4 Owner's Manual (English language PDF, page 338). We presume that this change only represents a difference in the naming of the specifications, but not in the underlying specifications that are indicated. The terminology differences are contrasted in the following table:

The NP-W235 battery only carries one printed capacity specification, 2200mAh, which is the Rating Capacity. The capacity value which would be determined from the battery name (a value of 2350mAh on the basis of the “235” in the name), is the Nominal Capacity. Note that the label's second occurrence of the 2200mAh value is preceded by the Chinese characters 额定容量 which generally have the meanings indicated in the Term (2) column of the table below.

Term (2) is commonly rendered as "Nominal". (Try copy-and-pasting "translate 额定容量" into your browser, and check the various results). However Fujifilm's NP-W235 English language usage, now renders Term (1) as "Nominal" (instead of "Typical"). The current Fujifilm usage essentially conflates the terms "Nominal" and "Typical". Because of this, we must be careful when making specification comparisons.

The practical difference between the two Capacity specifications (Rating or Nominal), is largely related to intention. The Rating Capacity (or Rated Capacity) can be seen as a more formal expression of the Capacity, and might be used where the intention is to specify a reference class, or to indicate conformity, in situations pertaining to regulations (examples of such would be, safety, statutory, or excise contexts). The Rating Capacity is also the proper specification to use whenever a capacity is required for the determination of other specifications (for example, to determine Energy Capacity). In contrast, the (now called) Nominal Capacity, (formerly referred to as the Typical Capacity), is appropriate for contexts where the intention is to inform user expectation. This capacity value can reflect optimal results obtainable under ideal usage conditions.

The reason Nominal Capacity and Rating Capacity differ in their values, is because they were determined under different measurement conditions. Controlled measurement conditions include discharge rate, discharge termination voltage, and reference temperature. Changes to any of these conditions will affect the outcome of the Capacity test. Recent Fujifilm batteries (such as the NP-W126 class batteries) used different reference temperatures for the Typical and Rated Capacity measurements of their internal cells, with 25°C being used for determining Typical Capacity, and with 20°C being used to determine the Rated Capacity.

Within the standard operational range, the measured battery capacity will be positively affected by increased ambient temperature, and negatively affected by increased discharge rate. This effect is known as capacity offset.

Differences due to testing conditions (in this case, the reference temperature) adequately account for the capacity variations when comparing Nominal Capacity and Rating Capacity values.

However, the main reason for the user to differentiate between Nominal Capacity and Rating Capacity, is to avoid making invalid comparisons between different battery models. For example, make sure that the Typical Capacity of the NP-W126S is compared with the Nominal Capacity of the NP-W235, and that the Minimum Capacity of the NP-W126S is compared with the Rating Capacity of the NP-W235.

[ 4 ] VOLTAGE

Voltage, or electromotive force, is the potential difference that the battery is able to effect across an energised circuit. There are two voltages printed on the NP-W235 battery: a Nominal Voltage, and a Maximum (or Charging) Voltage. The Nominal Voltage (7.2 Volts) is followed by the "solid line over dashed line" (Unicode symbol U+2393), which simply indicates that it is a Direct Current voltage. This 7.2 Volts is the expected Nominal Voltage for a twin cell Lithium-ion battery. The Maximum Voltage (8.4 Volts) is preceded by the Chinese characters 充电限制电压 meaning "Charging Voltage Limit".

Although Fujifilm does not specify a Minimum Voltage, this voltage is implied from the Maximum and Nominal Voltages, since (by definition) the Nominal Voltage lies halfway between the Maximum and Minimum Voltages. Because the battery uses two cells connected in series, the battery voltage specifications are double those of a single cell.

Battery voltage is not a constant, but continuously varies according to the battery's state of charge. Stating a Nominal Voltage is a way of attributing a virtual "fixed" voltage to the battery.

Note that, because the relationship between the battery's voltage and capacity, is non-linear, the Nominal Voltage does not necessarily coincide with the battery's 50% capacity point.

[ 5 ] NOMINAL ENERGY

Nominal Energy, or Energy Capacity, is the rating measure for the amount of energy that is stored in the battery. The Nominal Energy of the NP-W235 battery is 16Wh (Watt hours). It is determined by multiplying the Rating Capacity in Amp-hours by the Nominal Voltage of the battery.

Significantly, the NP-W235's Nominal Energy is even higher than that of the GFX system's NP-T125 (14Wh) battery. The big increase that came with the NP-T125 battery, was its ability to power a higher voltage (10.8 Volt) system.

The NP-T125 (GFX series battery) has been shown for comparison, while noting that the stated voltage and capacity do not produce exactly 14Wh. There is a another possibility, which is, that the NP-T125's Nominal Energy is actually 13.3Wh, and has been rounded up to 14Wh. This is reasonable if the specification is understood in the sense of "The battery's nominal energy does not exceed 14Wh", an appropriate assertion when set in a safety assessment context.

The International Air Transport Association (IATA) safety regulations, require lithium-ion batteries to be marked with the battery's Watt-hour rating on the outside case. The Watt-hour rating is the measure by which lithium-ion batteries are regulated. Batteries, power banks, and devices with batteries inside, are assigned to different risk categories on the basis of the amount of energy they hold (energy which could be released as heat, fire, or explosion). In this context, 100Wh is the significant threshold for being categorised into a higher, more stringently controlled hazard class. The NP-W235 battery (at 16Wh) falls well below this threshold.

When comparing different batteries solely on the basis of mAh Capacity, differing Voltages can be a confounding factor, reducing the validity of the comparison. Nominal Energy is a better specification for comparing the ability of batteries to drive a system, because it takes into account the Nominal Voltage of the battery, as well as the battery's Coulombic Capacity.

[ 6 ] DIMENSIONS

The battery's Dimensions specify its maximum extensions along various axes. The following figures are from the published dimensions of the NP-W235 battery. Of course, whether you consider the longest dimension to be a Height or a Length measurement, depends on the observational orientation of the battery.

This information, however, is of limited usefulness, because of the complexity of the battery's shape, when compared to that of a simple prismatic shaped battery such as the NP-W126S. For this reason, we would like to also take a closer look at the battery's Volume.

[ 7 ] VOLUME

The battery's Volume is not specified by Fujifilm, so it has been derived independently. Volume indicates the amount of space appropriated by the battery. However, with respect to total camera size, the idea that "smaller is always better" may be overly-simplistic, when we consider that a more "substantial" camera, can contribute to a more satisfying (and more sustainable) hand fit, and feel. Knowing the battery's Volume is advantageous, because it can be used to determine Volumetric Energy Density. (refer: Section [ 9 ] VOLUMETRIC ENERGY DENSITY ).

Although the Volume can be measured by displacement methods, I have used a graphical method to estimate the battery's Volume. In contrast to a prismatic battery pack, where it is a simple matter of multiplying its three dimensions, the Volume of a battery pack with complex shape details can be tedious to derive based on linear dimensions. However, if we ignore micro-details (deeming them trivial, in terms of their contribution to the total volume), and look only at the larger-scale shape of the battery, the Volume assessment process can be simplified considerably. If we can determine a cross-sectional area, it is only necessary to multiply it by the height (or length, depending on how you look at it) in order to derive a good approximation of the battery's Volume.

A distortion-free photographic image of the end of the battery, has been used as a surrogate for this cross-sectional shape. Applying a grid method for estimating the area of an irregular shape, a scaled 2 x 2 millimetre grid was overlaid, so that each grid cell represented 4 square mm.

The grid cells were each assessed as to whether they enclosed 0, 1, 2, 3, or 4 square mm (rounded to the nearest square mm) of the shape. Critical squares could be further divided in four equal squares or four equal triangles, as appropriate, in order to facilitate the assessment. In this way, the area of the image shape was estimated.

Based on this grid method, the cross-sectional area is approximately 776 square mm (1.2 square inches). Multiplying this area measurement by the length of the dimension perpendicular to it (52.3mm), gives a volume of approximately 40585 mm³.

The Volume estimate of 40585 mm³, is only 87% of the rectangular-prismatic volume (46386 mm³) which would be obtained by simply multiplying together the Height, Width, and Thickness.

With irregular shape profiles (such as this B-profile), space savings (due to contoured "form fitting" surfaces, for example), may not be able to be fully realised. For instance, the available space may be in locations where, in practical terms, it is of little use. Furthermore, to the extent that a camera's battery chamber might still take a basically rectangular shape, the reduced (due to contours) volume of the battery might be effectively negated. However, apparent "wastage" of potential free space (as air spaces or voids), may still be contributing to design efficiency in other ways, such as heat transfer control. For these reasons, the battery's space demands (how much bearing it has on the size of the camera), probably fall intermediate between the minimum footprint (based on the contoured shape), and the maximum footprint (based on the extreme dimensions of the virtual rectangular-prism shape).

Compared to the NP-W126S battery, the NP-W235 increases Rating Capacity at the cost of some "loss of compactness". Importantly, the Capacity gain offsets and exceeds the loss. Note that the NP-W235's true (not prismatic) Volume was used.

[ 8 ] WEIGHT

Battery weight contributes to the required long term effort involved in supporting the camera during use. However, the idea that "lighter is always better" is possibly overly-simplistic, when we consider that the extra inertia of an appropriately "weighty" camera, can contribute to stability in hand-held usage. The NP-W235 battery weight (from published specifications) is 79g, or 2.8oz. The (presumed) 18500 cells should weigh approximately 34g each, with the balance of the battery weight (about 11g) due to battery case and circuit board. For comparison, the NP-W126S battery weighed 47g total, with each internal cell weighing 20.3g, and the balance of the battery weight (about 6.4g) being due to the battery case, internal separator, and circuit board.

Compared to the NP-W126S battery, the NP-W235 increases Rating Capacity at the cost of some "loss of lightness". Importantly, the Capacity gain offsets and exceeds the loss.

[ 9 ] VOLUMETRIC ENERGY DENSITY

The battery's Volumetric Energy Density is not specified by Fujifilm, so it has been derived independently. The Volumetric Energy Density reflects the efficiency impact of the battery's spatial footprint on the camera size. It is specified in Watt-hours per litre (Wh/l). Provision of increased battery power, typically comes at the cost of increased camera size. If a new battery model has an increased Volumetric Energy Density value, that increase tends to justify any growth in camera size (due to larger battery).

The Volumetric Energy Density is calculated by dividing the Nominal Energy of the battery pack by its Volume. (For reference, one cubic millimetre is 1.0E-6 Liters). It is worth remembering that the total increase in camera size from the X-T3 to the X-T4, is not only due to increased battery size, but also to the inclusion of the new IBIS mechanism.

[ 10 ] GRAVIMETRIC ENERGY DENSITY

The battery's Gravimetric Energy Density is not specified by Fujifilm, so it has been derived independently. The Gravimetric Energy Density reflects the efficiency impact of the battery's mass on the total weight of the camera. It is specified in Watt hours per kilogram (Wh/kg). The provision of increased battery power, typically comes at the cost of increased camera weight. If a new battery model has an increased Gravimetric Energy Density value, that increase tends to justify any rise in camera weight (due to heavier battery).

The Gravimetric Energy Density is calculated by dividing the Nominal Energy of the battery pack by its Weight. It is worth remembering that the total increase in camera weight from the X-T3 to the X-T4, is not only due to increased battery weight, but also to the inclusion of the new IBIS mechanism.

**_[ 11 ] CHARGING TEMPERATURE PROTOCOLS

_**

In order to avoid cell degradation during the charging process, the Fujifilm charging systems (both in-camera and external), switch to different charge rates for different temperature ranges, or even suspend charging if the temperature is outside the allowable range. I will refer to this behaviour as implementing Charging Temperature Protocols. These Protocols are required by the battery, but implemented by the charging device. As an example of how this works, when charging the NP-W126S battery in the BC-W126S charger, if the thermistor resistance (read from the T terminal of the battery) reaches 27 kΩ (kilo-Ohms) or higher, it indicates that the (inversely related) battery temperature is 10°C (50°F) or lower. This temperature is too low for optimal charging, and triggers a charge current reduction from the normal 720 mA (a rate of 0.6 C), to the low-temperature charge current of 420 mA (a rate 0.35 C). These numbers were verified experimentally. The low rate is specified by Panasonic's data sheet for the NP-W126S's internal cells (NCA673440), where it states "At temperatures below 10°C, charge at a 0.35C rate". We expect the charging of the NP-W235 battery to be managed in the same way. The X-T4 Owner's Manual (English PDF, page 309) states that "Charging times will increase at ambient temperatures below +10°C (+50°F) or above +35°C (+95°F)". The reason for the increased charging times, is the reduction in charging rate, for these low and high temperature ranges.

In the past, third-party chargers have not replicated this temperature referenced behaviour, so we wonder, in the near future when we foresee third-party "NP-W235" batteries and chargers becoming available, whether they will observe these temperature based Charging Protocols. Whatever the case, the extent to which third party options are able to implement strategies to avoid cell degradation, will be of importance in determining the suitability, safety, and wisdom of choosing such options.

[ 12 ] OPERATING TEMPERATURES

There is an expectation that Lithium-ion powered digital cameras, like the X-T4, will be operated in a wide range of environmental temperatures. Within this range, the Lithium-ion battery should be able to perform efficiently and safely. The X-T4 Owner's Manual (English language PDF, page 338) specifies the battery's Operating Temperature range as 0°C to +40°C. However, this specification is too conservative in the low temperature range, where Lithium-ion batteries are able to operate at temperatures significantly below freezing (Note, this is for operation, that is, discharge, not charging ). If we consider the NP-W126S battery (also specified as 0°C to +40°C by Fujifilm), we find that Panasonic's data sheet for the internal cells, states a discharge temperature range of -20°C to +60°C. We would expect a similar range for the NP-W234 battery. The upper limit of this range aligns with the maximum temperature of +60°C printed on the battery.

Adding to the perplexity of this matter, on page 337 of the X-T4 manual, under "Power supply/other > Operating Conditions", a temperature range of -10°C to +40°C (+14°F to +104°F) is stated. I would suggest that the 0°C to +40°C range is a recommended Operational Temperature range (and possibly an amalgamation of the safe discharge temperature range, and the safe charging temperature range), while the -20°C to +60°C is the Absolute Environmental Temperature range, for the battery. In general, Lithium-ion batteries can be discharged well below 0°C (although the available capacity will be reduced). When Lithium-ion batteries operate at very low temperature, a typical decrease in efficiency is: while at -10°C the battery can deliver only about two-thirds of its normal capacity, and while at -20°C the battery can deliver only about half of its normal capacity. Although these very low temperatures are not ideal, the batteries can be utilised (but not charged) at these temperatures, and photographers do successfully use them down to -10°C and lower. Operating Temperature range is a specification area where Fujifilm could make further clarification.

A subset of the environmental temperature range is the Storage Temperature range. The X-T4 Owner's Manual (p. 309) states this range as +15°C to +25°C (+59°F to +77°F). This temperature range is to avoid cell degradation while the battery is not being used for extended periods of time. Although not explicitly stated by Fujifilm, the optimal storage temperature is the lower value in the range, about +15°C (+59°F), and the optimal state of charge during storage, is about 40 - 50%.

[ 13 ] PRODUCTION DATE

Mainly for the purpose of tracking production batches, OEM batteries are typically marked with a production number, which can identify the production lot, and possibly also, the date of production. Production lot information may be required for warranty issues, as well as for product safety notifications and recalls. Some standards, such as Korean Certification, require the production year, month, and lot number, to be provided. The new NP-W235 battery (unlike the NP-W126 series batteries, which required a decode-chart in order to determine the production date), follows the NP-T125 (GFX cameras) practice of clearly displaying the production date on the battery.

The first two digits indicate the year, and the second two indicate the month. Production date is relevant to the user because lithium-ion batteries typically give their best performance within a two year period of the time of production. Knowing the production date can assist in predicting when a performance drop-off is likely to begin, and in devising a replacement plan.

Although the X-T4 camera's "battery age" display function, might make knowing the production date superfluous in terms of battery replacement planning, the production date information can still be a useful unique identifier to distinguish between multiple batteries.

[ 14 ] SUMMARY

The Fujifilm X-T series mirrorless cameras have been renowned for their reduced size and weight when compared to DSLR cameras. With the release of the X-T4 and its bigger battery, there is widespread approval of the longer operation times available, but also some reservations about the effects on camera size and weight due to both the IBIS and the larger battery. The following table compares important properties of the NP-W126S and NP-W235 batteries, which affect performance against size/weight trade-offs.

Compared to the NP-W126S battery, the NP-W235 is more efficient, as is evidenced by its higher Volumetric and Gravimetric Energy Densities. This equates to more power for the package size and weight. The modest down-side costs of increased weight and size, are offset by a significant gain in Capacity, at advantage ratios that could not be achieved by simply designing the new camera to hold two NP-W126S batteries, for example.

This survey did not look at shots-per-charge, or video-capture endurance, since, as a matter of not only battery efficiency but also camera efficiency, such investigations are beyond the stated scope of the present study. However, We look forward to being able to test the new battery, in real world situations, where we expect the results to be different from those of the standard CIPA testing. I hope the present work will give users of the new X-T4 camera, a better appreciation of the NP-W235 battery, and contribute to realistic performance expectations.

APPENDICES

TEXT INFORMATION SOURCES

Fujifilm NP-W235 Operating Instructions: BL00005069-100
(日本語, English, Français, Deutsch, and Español)
and
Fujifilm NP-W235 Istruziono d'uso: BL00005069-300
(Italiano, and Pусский)

Fujifilm Digital Camera X-T4 Owner's Manual: BL00005063-201
(English)

TRANSLATION OF THE JAPANESE SECTION
The Japanese printed sections of the battery label read:

電式バッテリー
Electric battery

富士フイルム株式会社
Fujifilm Corporation

使用後は、リサイクル協力店へ
After use, take to a recycling center.

危 険 :
Danger:

大険・ 発熱、発炎、破裂の原因となるので、火・水中投入、加熱、分解、ショートなどしないこと。
Do not throw into fire / water, heat, disassemble, or short-circuit as this may cause serious injury, heat generation, fire, or rupture.

高温での充電、 使用、放置をしないこと。
Do not charge, use or leave at high temperature.

専用充電器以外で充電しないこと。
Do not charge with any device other than the dedicated charger.

TRANSLATION OF THE CHINESE SECTION
The lower four lines of the battery label (written in Chinese), read:

富士胶片株式会社
Fujifilm Co., Ltd.

锂离子电池组
Lithium-ion battery pack

型避:NP-W235
Type: NP-W235

中国组装
Assembled in China

充志限制电压 :8.4V
Charging voltage limit: 8.4V

额定容量 :2200mAh
Rated capacity: 2200mAh

注意:
Note:

禁止拆解、手击、挤压或投入火中。
Do not disassemble, strike, crush or throw into fire.

请勿置于高温环境中。
Do not place in high temperature environment.

电池浸水后禁止重用!
It is forbidden to reuse the battery after immersion in water!

[Last revised: 18/05/2020]

A NOTE OF CAUTION

The Internet is full of misleading and outright wrong "information". I make every effort to ensure that the information I present is factual, as best I am able to establish. However, there is always the possibility that I have made a mistake, or that my sources are in error. If you are going to use the above information as the basis for important decisions, or use it as a reference source for other informative works, I recommend that you exercise due diligence and seek independent verification of the accuracy of the information presented here.

Thanks for reading . . .

_**Fuji NP-W235 Battery

**_

_If you would like to support me in continuing to produce high quality reference material, like this, please consider donating, maybe even the cost of a coffee.
Ciao!
_

All images © 2020 Dom Varney

Photographic images on this page are licensed under a

Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

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The Great Battery Brawl

Fuji versus 3rd Party NP-W126/S

in a 12 Round Contest

" I need a new battery for my Fujifilm X-series camera. Should I buy the genuine Fujifilm OEM (Original Equipment Manufacturer) battery, or should I buy an alternative 3rd Party battery?"

With this question, you have just re-ignited a conflagration, a battle of opinions that has been raging for years. Those backing the 3rd Party Contenders, claim that you are just wasting money by buying the Fujifilm OEM battery, because the best 3rd Party batteries can deliver similar performance at a much lower price. The response from the OEM Champ's backers, is that any monetary savings represent false economy when the other "costs" of using a 3rd Party battery are taken into account (for example, they claim that safety is compromised). Well, it's time to finally settle this dispute. So now, get ready for the ultimate decider. But don't expect a knock-out; this will probably go down to a points decision. Be prepared to exercise minute attention to technicalities, because in this ring, YOU will be the referee, and the ultimate adjudicator. The contest will go a distance of 12 rounds:

1 - Price
2 - Capacity
3 - Discharge characteristics
4 - Temperature management
5 - Battery swelling
6 - Power capability
7 - Self discharge
8 - Battery ageing
9 - Control codes
10 - Warranty
11 - Reliability
12 - Ultimate value

" OK, Batteries. I expect a good, clean fight.
Protect yourself at all times.
Now, return to your corners and come out at the bell. "

[ 1 ] PRICE

Price is, of course, the pivotal issue of the contest, and we could even say, the " sine qua non" issue of the fight, since if there was no price difference between OEM and 3rd Party batteries, most people would just buy OEM.

PRICE DIFFERENCES
There can be very significant price difference between the Fujifilm OEM battery and even the most costly of the 3rd Party batteries. So it is understandable that people might consider the use of alternative batteries to the OEM battery.

In the above table (based mainly on the US market), the OEM battery has been assigned a value of 100 price units, simply to make relative costs more apparent, since they can be treated as percentages. For each of the batteries listed, the current $US price is about two-thirds of the "price units" value given (except for Patona brand which is not distributed in the US, and so, does not have a regular US "street" price).

COST VERSUS SERVICE LIFE
The OEM battery supporters claim that the 3rd Party batteries don't last as long as the OEM battery. But even if this is true, the shorter life is offset, to some extent, by the lower cost. To explore this, let's assume that the OEM battery can provide a service life of 4 years, or 48 months (which, based on experience, is a realistic assumption). Now compare it to a hypothetical 3rd Party battery, costing 35% of the OEM battery's cost (that would put it in the upper price group of 3rd Party batteries). This hypothetical battery's service life would have to be reduced down to about 18 months, before it started to become un-competitive with the OEM battery, on the basis of cost. If the hypothetical battery's service life turned out to be longer (which is likely for its price category), then the cost advantage over the OEM becomes even more compelling.

Of course, a shorter service life means that you have to purchase more batteries in order to match the OEM's 48 months of service. This repeating battery purchase produces other effects.

BUDGETARY ADVANTAGE
Assume a hypothetical 3rd Party battery, which only costs one third of the OEM cost, but only lasts one third of the OEM life. You would have to buy a second one, and then a third one, later, to match the life of the OEM battery. In the long run, the users of the 3rd Party battery, and the users of the OEM battery, both spend the same total amount of money over the same period of time. However, the lower cost battery effectively allows the user to spread the battery costs, and pay one-third now, one-third later, and another third later still. The user may appreciate this as a significant budgetary advantage.

MORE FREQUENT BATTERY FADE PERIODS
On the other hand, frequent battery renewal, comes with a more frequent experience of transitional service, due to battery fade. In the transition period (when the battery is coming to the end of its life), the battery goes from performing acceptably, to performing unacceptably. This period can be marked by annoying, unreliable, and uncertain battery behaviour; shots per charge drops rapidly, and the possibility of unanticipated "low battery" shutdowns is increased. You might prefer not to go through this transition period any more often than is necessary. However, if the 3rd Party battery can match the service life of the OEM battery, this argument has no merit.

PRODUCTION OF WASTE
Some people say "Buy cheap batteries, and just replace them frequently". However, if we again take the case of the hypothetical "one-third-price, one-third-life" battery, it could be argued that this battery produces three times as much waste (and three times the carbon footprint of production), because you have to buy three of them, rather than a single OEM one. In the long-term, the longest life battery (which may be the OEM battery), produces the least waste. This is an issue rarely raised, in the debate, but perhaps it should be, given our rising consciousness of environmental issues.

DELIBERATION
For the price issue, there are are reasonable arguments from both sides of the debate. But, although price differences are clear and substantial, there is a saying that "money is not everything", and a decision based on this criterion alone, may be superficial. The implications of battery choice are multivariate, and there are other significant issues that we need to consider. We will revisit the price issue when we eventually look at ultimate value.

[ 2 ] CAPACITY

Many 3rd Party batteries seem like a great "buy" because, not only are they cheaper than the OEM battery, but they also boast a higher capacity. Unfortunately, battery capacity is a complex topic, which is often poorly understood. It is worthwhile exploring this area in some depth. Let's try to make sense of the numbers.

The NP-W126S battery is a nominal 1260mAh (milli-Amp-hour) battery. The 1260mAh capacity is indicated by the "126" in the battery's name, which is the capacity, with the final zero dropped. In the same way, the GFX camera's NP-T125 battery is a 1250mAh battery (with the final zero dropped to give the name). This is Fujifilm's current battery naming practice for these and any new twin cell (NP-Wxxx, W indicating tWo or tWin), or triple cell (NP-Txxx, T indicating Three or Triple) batteries. (Note that the naming system used for the older single cell batteries is different).

The genuine OEM NP-W126/S battery was designed around the Panasonic NCA673440 prismatic lithium-ion cell. ("Prismatic" differentiates the shape from cylindrical and pouch type cells).

There are two of these cells in each battery. For reference, this cell has a volumetric energy density of 0.47 Watt-hours per cm³, and a gravimetric energy density of 0.213 Watt-hours per gram.

Recognition of the dual cell nature of this battery will be important for understanding some of the "capacity" concepts, and will help avoid some specification misunderstandings.

ELECTRICAL SPECIFICATIONS
The Fujifilm NP-W126S battery has 5 electrical specifications printed of its front face:

Because the battery's terminal voltage continually reduces during discharge (going from 8.4V down to 6.0V), the battery is assigned a "nominal" voltage, which is the half-way point between maximum voltage (8.4V) and minimum discharge voltage (6.0V).

3rd Party batteries typically state only the nominal voltage, nominal capacity, and the nominal energy of the battery.

Although photographers may pay little attention to the nominal energy specification, it is required to be stated on the battery for the purpose of determining compliance with air-transport regulations, because it is a better indicator of the amount of energy that could be released in an explosive or rapid combustion event. Using the nominal energy specification, batteries are differentiated into one of three categories (less than 100Wh, up to 160Wh, and over 160Wh), in order to determine which air transport rules apply to them (for instance, how many spares a passenger is allowed to carry). Stills camera batteries are all in the lowest (< 100Wh) category. For reference, one Watt specifies a power of one Joule per second, and one Joule is equivalent to one Newton-metre.

COULOMETRIC CAPACITY
This is the specification most people think of when considering capacity. The nominal, or coulometric, capacity, specifies a current (a flow of electrical charge) which can be sustained for a one hour period of time, and is expressed in milli-Amp-hours (mAh). The NP-W126S's 1260mAh nominal capacity can, in theory, continuously supply 1260 milli-Amps of current for 1 hour, or the various mathematical equivalents, such as, 630mA for 2 hours, or 2520mA for half an hour, etc. In practical terms, the nominal or coulometric capacity is an indicator of how much use we can expect to get from the battery before it requires recharging. In photographic terms, it will be a major factor in determining how many shots we get per battery charge. Coulometric capacity is closely related to the battery's internal cell size (and the volume of active material contained within the cell), but it is not directly related to total battery size, since it does not take into account the number of internal cells which comprise the battery.

ENERGY CAPACITY
The other measure of battery capacity is the battery's energy capacity, or nominal energy, expressed in Watt-hours (Wh). The nominal energy can be found by multiplying the capacity by the nominal voltage. So, for the NP-W126S battery, the nominal energy would be: (1.20Ah x 7.2V) = 8.7Wh. (Note that Fuji uses the minimum capacity, 1200mAh, rather than the typical capacity, for this calculation). The nominal energy is often overlooked, however it does put battery capacity into a different perspective, and also resolves the "typical capacity" anomaly that can be noticed when, for instance, comparing the three different sized batteries in the following table.

It might seem counter-intuitive that the biggest battery (the NP-T125), has the smallest "typical" capacity, while the smallest battery (the NP-95) has a significantly higher capacity. To simplify the explanation of the difference between the two types of capacity specification (energy and coulometric): one specification answers the question "How much?" (energy), while the other answers the question "For how long?" (running time). The battery's nominal energy, expressed by its Watt-hour (Wh) rating, takes into account the voltage of the battery, and that normalises the relationship between size and "capacity". The voltage will depend on the number of cells in the battery pack, which ranges from single to triple, for still camera batteries. The cells are connected in such a way that their individual voltages (3.6V) add together, but the total mAh capacity does not change from that of a single cell. All NP-W126 type batteries, will be twin cell, and have a reference voltage of 7.2 (or 7.4) Volts. Because the nominal voltage is a mid-point voltage, between maximum voltage and lowest allowable discharge voltage, if the manufacturer uses different end-points (specifically, a different minimum discharge voltage), then the mid-point voltage can vary. This explains why some 3rd Party batteries state their nominal voltage as 7.4 Volts. However, the 7.2 Volts and 7.4 Volts are only "indicative" voltages, and they effectively point to the same characteristic voltage.

DIFFERENCES IN MARKET CAPACITIES
The reason the Fujifilm NP-W126S battery has a nominal capacity of 1260mAh is, because that's about the capacity limit for a battery of that size within the constraints of the current lithium-ion technology. Since the OEM and 3rd Party batteries are all the same size (they have to be, in order to properly fit the camera's battery chamber), why do the various 3rd Party battery manufacturers specify different capacities? A survey of 3rd Party NP-W126 batteries on the market currently, has batteries ranging from 1600mAh down to 950mAh. (I did not include the claimed "1900mAh" batteries, on the basis of their lacking credibility).

There are several explanations for this wide discrepancy in quoted capacities for batteries of the same physical size:

CAPACITY TESTING CONDITIONS
In testing, the capacity may have been determined at a different discharge rate (C-rate) than the OEM battery. Since capacity varies with C-rate (an effect called capacity offset), this can lead to differences in the reported capacities. If the discharge testing is performed at a low discharge current, the measured capacity will be higher, and if performed at a high discharge current, the measured capacity will be lower. When increasing the C-rate from 0.2C to 1.0C, the capacity reading is decreased by about 10%. Capacity testing at different ambient temperatures will also cause variation in the reported capacities. For instance, a battery that recorded 1220mAh of capacity when tested at 25°C (77°F), might only record 1200mAh when tested at 20°C (68°F).

The Fujifilm battery specification is based on a discharge rate of 1.0C, at 25°C / 77°F. Full specification data sheets for lithium-ion cells (like the NCA673440) will specify the C-rate and ambient temperature at which the capacity was determined. However, similar information for the internal cells of 3rd Party batteries is, in practical terms, "un-discoverable" for most battery users.

TYPE OF SPECIFICATION
The manufacturer can have quoted either the maximum capacity, the typical (or average) capacity, or the minimum (or rated) capacity. The capacity could also be an indicative capacity based on theoretical calculations (for example, cell weight multiplied by the typical gravimetric energy density ), rather than practical measurements. Most frequently, it it not stated which of these specifications is being used.

OPTIMISATION
The specific design of a battery's electrochemistry either optimises it for Power, or optimises it for Capacity, but the battery can't be optimised for both. The power oriented battery is able to answer demands for continuous high current (such as might be needed for shooting 4k video). In contrast, the capacity oriented battery, is able to supply low power photographic use (single-shot stills shooting, at a low rate), for a large number of shots.

Because of this difference between power optimised and capacity optimised batteries, it is possible for a 3rd Party battery to get more shots per charge than the OEM battery, but then perform poorly when supplying power for high definition video, or high frame rate, continuous shooting.

LOWER CAPACITY CELLS
A lower quoted capacity may indicate smaller internal cells, so there is less active material (the substances responsible for the electrochemical activity which produces the electricity). That reduction in the amount of active material would show up as a measurable reduction in battery weight. Note that even a slight decrease in the cell's linear dimensions, can produce a significant decrease in volume, weight, and nominal capacity. For instance, compare the NCA673440 with the FT603040 lithium-ion cell, which appears to be about the same size:

(The chart also shows that the string of numbers in each cell name, actually indicates the approximate cell dimensions). The OEM battery weighs 47 grams or 1.66 oz (20.3g for each cell, and about 6.4g for the circuit board and case). The lower capacity battery's weight may go down to around 40 grams or 1.4 oz (with about 15g per cell, plus a few grams of packing material, to hold the slightly smaller cells in position).

Lower stated capacities are probably reliable, since there is little market advantage to be gained by quoting a lower capacity than the competitors. One important point regarding lower capacity batteries, is that they are more likely to overheat while charging, leading to swelling. This is because the charger is typically designed to charge a 1200mAh battery, so the charging current might be higher than is optimal for the lower capacity battery.

CONFUSED SPECIFICATIONS
A 3rd Party battery producer (the battery assembler, rather than cell manufacturer), may be confused about the conventional way of determining or stating a battery's electrical specifications. The problem is typically due to a confusion between cell specifications, and battery specifications (A battery is a cluster of cells, in the case of the NP-W126 battery, two cells). Specifically, there can be confusion over whether or not a particular specification should be doubled, due to the use of two cells in the battery.

In the first example (shown above), the stated voltage of 3.7V, is the cell voltage, where they should have stated the battery voltage of 7.4 Volts (2 x 3.7V). As a consequence, the nominal energy specification of 3.5Wh is also wrong; It should have been 7Wh. In the next example, the nominal capacity is stated as 1360mAh.

Upon opening the battery, the internal cells were found to be 680mAh capacity (from the cell manufacturers specification sheets). The battery capacity should have been stated as 680mAh, and should not have been doubled to give 1360mAh. My experience is that this error is quite frequent. Be wary of any NP-W126 type battery stating a capacity higher than 1300mAh. You will often find that they are actually half the stated capacity. However, they can still work well, even if giving less shots per charge than the OEM battery.

EXAGGERATED SPECIFICATIONS
The final reason for a wide variation in capacities is that the battery may have its specifications mis-represented, or exaggerated. At least one battery on the market boasts 1900mAh capacity, but actually delivers less than 700mAh.

Erroneous "doubling" of 700mAh would only have given about 1400mAh (still on the high side). If the discrepancy between claimed and actual capacity is significant, and intentional (with the goal of deceiving), then the battery is a fraudulent battery. There is no need to consider these un-trustworthy batteries any further.

TRADE-OFFS
If the battery is specified as a higher capacity than the OEM battery, you should reflect upon why this could be the case, and take that into your considerations. Don't expect to get higher capacity than the OEM battery, without some other trade-offs, which could be in terms of, poorer performance under heavy loads, increased self-discharge rates, decreased battery life, etc.

DELIBERATION
Due to the reasons given above, it it typically not very productive to compare batteries on the basis of their self-quoted capacities. Also, to get battery performance that is similar to the Fujifilm OEM battery, the 3rd party manufacturer should strive to use battery chemistry close to that of the OEM battery, and so we would expect a similar (not higher) mAh capacity. Highly respected 3rd Party batteries like Watson and Patona, quote capacities that are very similar to the OEM battery's capacity. My own experience, and that of many others, is that the best 3rd Party batteries can deliver a capacity similar to the OEM batteries. However, even with a genuinely equivalent capacity to the OEM battery, there may still be differences in power delivery rate, self-discharge rate, and ultimate rate of decline in battery's SoH (State of Health). So, although capacity need not be a deal breaker issue for the OEM vs 3rd Party decision, it is not the only performance specification that needs to be considered.

[ 3 ] DISCHARGE CHARACTERISTICS

Discharge characteristics can be an issue, because they affect the feedback that the camera gives to the user, regarding the battery's State of Charge (the remaining charge of the battery). This is what is indicated by the battery level display when we are using the camera. The battery level indicators of the Fujifilm X-series cameras, are calibrated for the Fujifilm OEM batteries. Because other batteries differ in their chemistry, they produce different discharge curves (voltage plotted against capacity).

Not only are discharge plots non-linear, but those typical of 3rd Party batteries also have a different shape and more prominent inflection points, in comparison to the OEM batteries. Because of this, the battery level indicator produces some anomalies when using these 3rd Party batteries.

A typical experience when using 3rd Party batteries under high power discharge situations (4k video, or high frame-rate continuous shooting), is that the charge-remaining indication is exaggerated (the actual capacity is less than what is shown), and there is little or no warning given of immanent shut-down due to battery depletion. Frequently, the indicator goes from two bars directly to empty.

For some photographers, this is both annoying, and disruptive of workflow, due to insufficient warning of power shut-downs. Other photographers just adapt, and prepare for a battery change whenever the "two bars" indication is reached. Besides, if you are not putting extreme demands on the camera, the effect is much less noticeable.

OLDER CAMERAS
If you are using an older X-series camera (pre X-T2), any display differences due to different discharge characteristics, may be a minor issue.

The older battery level display lacked resolution, and may not differentiate OEM from 3rd Party batteries in any meaningful way.

DELIBERATION
This issue does not actually affect the battery's functionality in terms of capacity, shots per charge, or life expectancy. It might be considered as an issue affecting the quality of the user experience, and its significance, will very much depend on your personal tolerance for such technical anomalies.

[ 4 ] TEMPERATURE MANAGEMENT

Temperature management is a critical issue for lithium-ion battery safety and service condition. Although reported cases of catastrophic failure are fewer than with, as an example, notebook computer batteries, incidents with camera lithium-ion batteries do occur. Reported cases of camera battery related venting and combustion events include: A camera battery catching fire on an aircraft departing Chicago O'Hare Airport in 2013, a smoking camera battery at Raleigh Durham Airport (North Carolina) in 2017, an exploding camera battery at Orlando International Airport in 2017, and a camera battery catching fire (while charging) in Norway during 2018. Probably, most incidents occurring in a domestic context are not reported.

Extreme temperature conditions can both damage the battery, and/or render it unsafe. When being charged, lithium-ion batteries must not go outside of the temperature range 0°C to 45°C (32°F to 113°F). At temperatures below 0°C / 32°F, metallic lithium becomes permanently plated on the cell's anode (effectively producing a loss of available lithium salts for the electro-chemical process), and ion diffusion rates on the anode are reduced. At temperatures above the upper allowable range, there is cumulative and permanent loss of capacity and reduction in charge acceptance.

If a lithium-ion battery reaches about 150°C (about 300°F), it may vent (the cell's pressure relief valve opens, or its "burst plate" ruptures, to relieve pressure).

During venting, not only are highly flammable gases released, but electrolyte can also be released as liquid, droplets, or vapor. If venting occurs while inside the battery chamber, the battery can leak hot electrolyte fluid (containing solvents) from its terminal openings, into the battery chamber. Electrolyte leakage will be noticed as a black residue in the terminal area. In the worst case scenario, if the battery is able to reach a temperature of over 200°C (390°F), second venting and thermal runaway can occur. Thermal runaway will be the prelude to a violent incendiary event.

Because of the hazards posed by lithium-ion batteries, if operated outside of their "safety envelope", all lithium-ion camera batteries include a circuit board for battery management and protection. Ideally, the circuitry should maintain balanced cell capacities, and guard against deep discharge, overcharging, short-circuit or over-current, and temperature range violation. The following image shows a circuit diagram representing is a protection circuit arrangement.

At a minimum, the circuit board typically uses a purpose-designed lithium-ion controller IC, combined with a MOSFET (metal oxide semiconductor field effect transistor) device for on/off switching of current.

Below is shown the actual protective circuit board (which also serves as the terminal board), of an Fujifilm NP-W126 battery.

Besides the positive and negative battery terminals, the protection board for the NP-W126/S or equivalent batteries, also has circuitry connecting to [S] and [T] terminals, so that there are four battery terminals.

The [T] terminal (standing for either Temperature or Thermistor), is (or should be) integral to the thermal protection of the battery while charging.

OEM USES THERMISTOR
The Fujifilm OEM battery uses a thermistor (implemented as a tiny surface mount device on the battery's protection circuit board), for temperature management. A thermistor is resistor whose resistance output is highly temperature dependent.

In its NTC (negative temperature coefficient) form, the resistance is inversely related to the thermistor's temperature. NTC thermistors exhibits a large, precise and predictable decrease in resistance as their core temperature increases.

Other reasons for using the thermistor are, good tolerance to shock and vibration, and little need of output signal conditioning (just a single capacitor for ripple suppression). The small size of the NP-W126/S thermistor (less than 1mm long), gives a low thermal mass, resulting in minimal lag for measurement of rapidly changing temperatures. The thermistor outputs a 10kΩ (kilo, or thousand, Ohm) resistance at a temperature of approximately 25°C (77°F). A reduced resistance indicates an elevated temperature, and vice-versa. The [T] terminal of the BC-W126S charger (or the camera, if utilising in-camera charging) reads the resistance on the battery's [T] terminal, and is able to determine the battery's internal temperature, and decide whether it conforms to the safe-charging temperature limits. Charging is terminated if the battery temperature goes outside the safe range.

NO THERMISTOR IN 3rd PARTY BATTERIES
Although it would seem reasonable to assume that 3rd Party batteries would implement this same thermistor driven system of charge-temperature management, it is generally not the case. 3rd Party batteries generally do not employ a thermistor. However, simply omitting the thermistor is not really an option, because the Fujifilm chargers (and cameras capable of in-camera charging), will not allow charging to initiate, unless a resistance indicating a temperature within the safe operating range, is found on the battery's [T] terminal. (You can verify this by placing a small piece of tape over just the [T] terminal of any "NP-W126" battery, and trying to charge it in a Fujifilm charger, or by using in-camera charging; charging will be blocked). In order to fulfill this "valid resistance" requirement, the 3rd Party batteries typically use a simple fixed-value, 10kΩ resistor in place of the thermistor circuit. The fact of the 10KΩ resistor substitution, is verified, not only by measuring resistance at the [T] terminal over a wide range of temperatures, but also by "cracking-open" various 3rd Party batteries, and examining the circuit boards. Note that the charger (or camera) is unable to tell whether the resistance being read is output from a thermistor or fixed value resistor. If you have an understanding of printed circuit boards and know what a "via" (vertical interconnect access) is, you will be able to trace the 3rd Party battery "T" circuit on the following image.

The result of using the 10kΩ fixed-value resistor, is a battery which tells the charger or camera, that the internal battery temperature is a very acceptable 25°C (77°F), regardless of the actual battery temperature, and even if the actual temperature is outside the safe range. Although precision grade (limited variation from the nominal specification) and aged (which reduces the tendency to "drift") thermistors can be costly, it is probable that using a resistor rather than a thermistor, also has some fabrication and assembly advantages for the 3rd Party battery maker, besides cutting component costs.

CONSEQUENCES OF NO-THERMISTOR
Likely consequences of not implementing the thermistor circuit are that, each time the charging process transgresses the allowed temperature range, the battery sustains some cumulative and non-reversible damage. Its performance might decline (and a corollary of this would be a reduction in service life), and the battery may eventually begin to swell, due to internal pressure caused by the over-heating, with the possibility of becoming stuck in the camera's battery chamber. Less-likely (based on the relative infrequency of reports) but more extreme consequences are the battery catching fire or exploding.

TEMPERATURE MANAGEMENT AS A SYSTEM
Does that mean that by using an OEM battery, my charge process is always temperature protected? Actually, "No". Importantly, thermistor temperature management is a system , which not only requires the battery's ability to send its temperature information, but also the charger's (or camera's) ability to read and interpret that temperature information.

So, if you have a Fujifilm OEM battery (with thermistor), but you are using a 3rd Party charger with no [T] terminal, the thermistor data is virtually useless, because the charger has no way of reading it. If you are using a USB charger (which Fujifilm does not offer), you may notice it has no [T] terminal, and therefore there will be no temperature management advantage by OEM batteries over 3rd Party batteries, despite having a thermistor.

An exception to this, is the Nitecore FX1 dual (the second battery bay is on the underside) USB charger, which does have a [T] terminal, to monitor the thermistor readings. However , protection, in this case, is not automatic. The FX1 charger will report the correct temperature of a thermistor equipped battery, but it does not terminate charging if the battery goes outside the 0°C to 45°C allowable charging temperature range. The user needs to stop the charging process if they notice that the temperature display is approaching the 45°C charge temperature limit. [Thank you to Michael Kluth, who provided further valuable information regarding the FX1 charger 's operation].

However, in-camera or in-grip charging, always accesses the [T] terminal, which is why older Fujifilm cameras like the X-T1, which only had two battery terminals in the battery chamber, could not have implemented in-camera charging.

If you are using a two terminal ( [+] and [−] only ) charger, then the having or not having a thermistor by the battery, becomes an irrelevant factor. On the other hand, the JJC DCH-NPW126 USB dual charger has a temperature sensor built into the body of the charger, and this should extend over-temperature (but probably not under-temperature) charge protection to all batteries, whether they have a thermistor or not.

The Watson Duo Charger also states in the Owner's Manual (page 5), that it provides overheat protection: "The Duo Charger senses when the battery is about to overheat and immediately stops charging".

Once again, the heat sensor must be built into the charger, because the battery mounting plates do not have contacts to read a thermistor built into the battery. (There may be other chargers with built in temperature sensor, but I am unaware of any verified alternatives, at the moment).

The charge temperature management that you get (or don't get), depends on your combination of battery and charger setup. By selecting an appropriate battery-and-charger combination, you can ensure protection from over-heating, even when using 3rd Party (no thermistor) batteries.

COLD CLIMATES
If you are living in a very cold climate, and you are not using high C-rate charging, battery over-heating while charging may not be an issue. It is normal for the battery's temperature to rise by about 5° of the Celsius scale, or 9° of the Fahrenheit scale, during moderate C-rate charging. In very cold conditions, the battery's temperature might be able to rise by several times that amount, without getting close to the upper limit for charge-temperature. In cold climates, your main problem may be to ensure that you do not attempt to charge the lithium-ion battery at freezing or sub-freezing temperatures (which will severely damage the battery, due to lithium plating).

HIGH CHARGE RATES
Batteries become hotter when charged using high currents, so charge rate is relevant to temperature management. C-rate specifies the limiting current during charging or discharging of a battery. The C-rate is the ratio between capacity (in milli-Amp-hours) and current (in milli-Amps), normalised against a time period of one hour. So if we use a 1200mA current to charge a 1200mAh battery, (a ratio of one to one), the charge time would be (in theory), one hour, and the C-rate would be 1C. If we used 600mA of current to charge the same 1200mAh battery, the time taken would be two hours, and the C-rate (only half the charging efficiency of the first case), would be 0.5C. Please note that, during the second half of the charge process (the saturation phase), the current rapidly drops below the value represented by the nominal C-rate, so you cannot accurately calculate charging times, based solely on the C-rate.

For a 1200mAh battery, 0.7C or higher is considered a "high" C-rate, which would indicate a charge current of about 840mA, or higher. It is generally not advised to charge batteries of the NP-W126/S type, at C-rates higher than 0.7C (although the Fujifilm BC-W126S charger can output 0.75C, compared to the 0.6C of the previous BC-W126 charger). Most of the regular (not-fast) chargers use a C-rate of about 0.5C (so, current value is half the capacity value), which gives a charge current of about 600mA. In comparison, the Nitecore FX1 charger is rated at a maximum output current of 1000mA, and so it would be considered a "fast" charger.

This high charge rate is possible because because the user can monitor the temperature on batteries that have a thermistor. (But what if the battery doesn't have a thermistor, and so tells the charger that it is 25°C, regardless of its actual temperature?)

DELIBERATION
On the issue of charge temperature management, the battery cannot be considered in isolation from its intended method of charging. If you are considering a setup that does not implement charge-temperature management, you should satisfy yourself that the risk of battery swelling, or even of a catastrophic-failure type charging event is minimised and acceptably small.

[ 5 ] BATTERY SWELLING

Battery swelling is a common phenomenon with some 3rd Party batteries. However, it is virtually unknown with properly charged and used Fujifilm OEM batteries. The several cases I know of, where the "Fujifilm" battery was reported to have swollen, each turned out to be a counterfeit battery.

CAUSES OF SWELLING
Swelling, where the central thickness of the battery noticeably (and permanently) increases, indicates that the battery has been overheated, usually during charging. Overheating produces gasses, mainly hydrogen and carbon-dioxide, as well as carbon monoxide and ethylene (C2H2) from reduction of the ethylene-carbonate electrolyte. This evolution of gases increases the internal pressure of the two prismatic cells, and causes deformation tending towards a spherical form, because the round shape distributes the pressure induced stresses more uniformly. Because there are two prismatic cells, there are four significant deformation surfaces. Upon cooling however, the external to internal pressure gradient is insufficient to return the cells to their original flat shapes.

TOLERANCES
The NP-W126/S battery fits the X-cameras by fairly narrow tolerances (less than 5%). On the X-T3, the battery's fit to the battery chamber allows about 0.5mm (20 thousandths of an inch) of "play" in the dimension sensitive to swelling, to allow for easy insertion. That play is equivalent to about 3% of the battery's nominal thickness.

In comparison, a heavily swollen un-branded battery that was assessed, exceeded the chamber width measurement by 0.4mm (16 thousandths of an inch), giving about 6% increase to the central thickness.

There is enough structural "give" in the battery chamber that, by pushing firmly, you would be able to fully seat the swollen battery, (which would "wedge" its way in, because the battery's ends are typically not swollen, only the centre). However, the battery will not easily release, and you may have to resort to heavily striking the camera against your hand ("inertia" release), a damaging use of tools ("extraction" release), gluing a tab to the end of the battery ("adhesive" release) or even having to partially dismantle the camera, to get the battery out.

EFFECTS OF SWELLING
A swollen battery poses the following problems. If inserted into the camera's battery chamber, it may become difficult to remove, and there is the risk of damaging the battery chamber in attempting to remove the battery. If the battery swells significantly while inside the battery chamber (this could happen if you are utilising in-camera charging of a "resistor instead of thermistor" type battery), the battery could stress, bend, or crack, the chassis and circuit boards that either form or adjoin the walls of the battery chamber. However, even if the battery does not cause camera damage, a swollen battery will continue to decline, not only in capacity but also in safety, and needs to be (properly) disposed of.

EXPANSION
Although the Fujifilm OEM battery is reputed not to swell, it is natural for most substances to expand when they are heated. Because the battery's internal cells are sealed, we would expect some (even if extremely slight), "expansion" during the normal charge process. The OEM battery has a construction which is able to manage this. The two faces of the OEM battery's polycarbonate case (and the internal cell separator) are actually membranous.

The centre thickness of this flexible membrane is only 0.25mm (9.8 thousandths of an inch). It's thin enough that light will pass through it.

As well as this, the membranous surface is concave (curving inward) in shape, with the centre of the faces shallower than the edges of the case, by about 0.3 mm on each side.

This thin and flexible construction gives a case that is able to expand slightly in its middle thickness, without actually altering the nominal specifications. Therefore, any slight expansion (not enough yet to be considered "swelling"), by the OEM battery, can be accommodated. The practical difference between expansion and swelling, is that expansion is reversible (the deformation to the cell case has not exceeded the case material's elasticity yield-point), while the deformation of swelling has "passed the point of no return". In theory, the OEM battery could expand by up to 0.6 mm in its middle thickness, and still maintain the full 0.5mm "play", and without making any difference to the battery's fit in the chamber, or to its ease of ejection.

DELIBERATION
The risk of battery swelling is one of the main arguments used by the proponents of the "only use OEM batteries" position, and for some people, is a deal-breaker with regard to using 3rd Party batteries. However, that risk may be mitigated by, over-heat protection while charging, avoidance of in-camera charging, living in a cold climate, and your own careful attention to the condition of the battery, and to any changes it displays. Also, check on-line forums for whether a particular brand of batteries has a reputation for swelling (some do).

[ 6 ] POWER CAPABILITY

Whereas energy capacity (in Watt-hours) is concerned with the battery's capacity to store electrical energy, power (in Watts) is concerned with the ability to deliver that energy, for use. The ideal is that all of the released energy should be available to power the camera, but due to various inefficiencies, some energy is always lost as heat.

In the following, the ability to release high usable power, while limiting heat related losses, will be referred to as the performance level of the battery. The Fujifilm X-series camera batteries have evolved from a standard performance level (the NP-W126) to a higher performance level (the NP-W126S battery). The newer NP-W126S battery, replaces the NP-W126, even though its higher performance level is not required by the older (pre-XT2) X-series cameras. Importantly, there is no difference between the two battery types, in either energy capacity or coulometric capacity, since this performance issue is related to battery heating, and the battery's rate of power delivery.

PROPRIETARY INFORMATION
How the battery's manufacturer, Panasonic Energy, was able to realise the performance increase, is proprietary information. However, the problem that they addressed would typically have involved one or several of the three electrochemical overpotentials or polarisations (activation polarisation, concentration polarisation, and ohmic polarisation) which reduce a battery's power efficiency, and ultimately lose electricochemical energy as heat. Considering that the physical and electrical specifications of the type "S" battery remain unchanged from the original, the improvement strategy most likely involved the use of electrolyte additives to improve the battery's electrochemical efficiency. Whatever the precise improvement strategy, such information is rightly considered an industrial secret, so it is not a situation where the competitors can simply copy and apply the same solution.

" S" VERSUS "NON-S"
In practice, the higher performance "S" battery can work at power levels where the standard performance battery might not be able to keep up with the power demand. The standard performance battery's failure to meet that demand, may even trigger a camera lock-up event.

In order for the latest high-performance cameras to know whether the loaded battery "can deliver" in these high demand situations, the batteries have a way of "signalling" their class of performance level. This information is supplied over the battery's [S] terminal. After assessing the type, the camera indicates the type to the user, by way of alternative colours (yellow or white) for the battery level indicators, and by way of a possible advisory message at power-up time, on cameras where the difference matters (such as X-H1 and X-T3).

YELLOW OR WHITE
When a battery is loaded into a capable high-performance camera (X-H1 or X-T3), the camera interrogates the resistance on the [S] terminal of the battery. If the resistance is 100kΩ, the camera determines the battery to be either an OEM NP-W126 battery, or a 3rd Party equivalent, and the battery level display is in yellow. However, if the resistance shows as 680kΩ (thus exceeding a set resistance threshold), then the camera determines the battery to be an enhanced power delivery capable NP-W126S battery, displayed in white.

In this second case (NP-W126S), I did not say, "or a 3rd Party equivalent", because it is still uncertain whether there really are 3rd Party batteries that can provide the same performance level as the OEM NP-W126S battery. Definitely, 3rd Party batteries are coming onto the market, claiming to be NP-W126S equivalents, and even registering as such when inserted into an X-H1 or X-T3 camera, however, there is more to this than meets the eye.

" S" RESISTANCE
The original OEM NP-W126 battery showed a 100kΩ resistance at the [S] terminal, so the power management boards of 3rd Party batteries implemented a 100kΩ resistor to give the same reading on the [S] terminal as the OEM batteries did. That made sense, because the 3rd Party batteries were intended to be an interoperable alternative to the OEM batteries.

Now, however, we have a situation where the OEM type "S" battery (with enhanced performance) gives a 680kΩ resistance at the [S] terminal, which indicates that it is a type "S". The problem is, the manufacturer of a non-OEM battery (still using the previous, standard performance chemistry), can substitute a 680kΩ resistor for the the protection board's 100kΩ resistor (or simply omit the resistor, and leave the [S] terminal open-circuit). A battery with the appropriate [S] terminal resistance can pass itself as a high performance version, although the only thing changed was the "signalling" resistor.

EASILY MANIPULATED
You can verify that the type "S" indication can easily be manipulated, by placing a small piece of tape over just the [S] terminal of a "non-S" type battery (either OEM, or 3rd Party). This makes the [S] circuit an "open circuit", and changes the resistance to a virtual "infinite resistance", which (by definition) exceeds the set resistance threshold for type "S" indication. Insert the battery into an X-H1 or X-T3 camera, and, Voilà! Now the battery registers as an NP-W126S battery, it shows a white battery level indicator rather than yellow, and the several seconds duration "PLEASE USE NP-W126S BATTERY, etc" advisory message does not display, even though the battery has the chemistry of the standard performance type.

RELIABILITY OF "S" INDICATION
Fujifilm cameras are designed to be used with Fujifilm OEM batteries, and the purpose of the [S] terminal reading is to differentiate between different types of Fujifilm OEM batteries, not to differentiate between OEM and 3rd Party batteries. So the [S] terminal implementation gives reliable information when Fujifilm OEM batteries are used. But, the "S" indication cannot absolutely be relied upon when 3rd Party batteries are used. Just because the label on a 3rd Party battery states that it is an NP-W126S equivalent performer, does not mean that it is. And just because a 3rd Party battery registers in an X-H1 or X-T3 camera as an NP-W126S, does not mean that it will give equivalent performance to the OEM battery. Although 3rd Party manufacturers may be able to boost their battery performance to be equivalent to the OEM NP-W126S battery, the "equivalence" will depend on their performance , not on their in-camera battery indication. As an example of this unreliability, note the anomaly displayed by this pair of, otherwise identical, batteries:

A 3rd Party battery's "S" designation, is not a reliable indicator of its performance. It may be higher performance, or it may just be print and electronically labelled as such. At the moment (early 2019) I am inclined to ignore any 3rd Party battery's claimed "S" designation, and rely on my own assessment of the battery's performance.

DELIBERATION
It is not proven yet, that non-OEM batteries are able to achieve exactly the same power delivery rate as the Fujifilm OEM battery, and type "S" claims on 3rd Party batteries should be treated with caution. However, inability to achieve true type "S" performance may not be relevant, if you don't actually need it. Type "S" performance is not required by all X-series cameras, and Fujifilm even states that the cameras prior to the X-T2 will not benefit from the higher performance level. Furthermore, even if you have a camera which can benefit from the performance improvement, your own shooting style may not. If you use your camera mainly for landscape photography, for example, you are unlikely to require that performance level. If you don't shoot 4K video, if you don't use high rate continuous shooting, and if you don't have continuous auto-focus turned on all the time, you probably don't require the higher performance level. Remember, the standard performance level does not mean that you get less capacity.

[ 7 ] SELF DISCHARGE

Even without being used, a battery is always in a state of running down. All batteries are subject to a deficiency known as self discharge. An elevated level of self discharge is experienced as a charged battery which is unable to retain a high level of charge over a period of days or weeks, when not being used. The cause is an internal current flow called leakage current. Part of the leakage is due to inefficiencies in the battery's electrochemical makeup, and part is due to leakage through the protection board's circuitry. Self discharge is also highly dependent on ambient temperature, with higher self discharge rates occurring at higher ambient temperatures. Exposure to temperatures beyond the normal operating range (ie, above 45°C / 113°F) will increase the battery's future self discharge characteristics, even at normal temperatures. A low rate of self discharge is a desirable quality in a battery. A commom criticism of 3rd Party batteries is that their self discharge rate is higher than that of the OEM battery. Please note, that a battery installed in the camera body, will experience increased discharge while not being used, due to stand-by current (while awaiting a power-up signal from the camera's on-off switch), and due to powering the cameras clock-calendar. This is discharge by the camera, rather than self discharge.

BENCHMARK
A normal rate of self discharge after full charging, would be 5% loss in the first 24 hours, and a further 5% loss (2% intrinsic and 3% due to the battery's management board), over the rest of the month. So at the end of one month, the battery should still have 90% of its fully charged capacity.

MEASUREMENTS
A standard method for measuring self-discharge is to perform a standard charge, store the battery for 30 days at 25°C±0.5°C, and then perform a standard capacity test. Because there is a relationship between open circuit voltage (the voltage you would measure when the battery is not in the camera) and State of Charge (the capacity remaining), an alternative method is to to monitor a battery's open circuit voltage (with a digital multi-meter), at regular intervals over a period of days and weeks. A good result would be approximately 14 milliVolts decrease per day, after the first 24 hours.

DELIBERATION
Because self discharge reveals itself over time, photographers who charge their batteries just before use (so there is no interim period between charging and usage), may not be affected by moderate degrees of self discharge. However, in advanced cases, the loss of charge may be noticeable over a period of hours. Battery self discharge is a fact of life. The question is whether the 3rd Party battery can equal (or perhaps even better) the low self discharge characteristic of the Fujifilm OEM battery.

[ 8 ] BATTERY AGEING

All batteries decline in their capabilities over time, and eventually reach a point where their ability to perform does not meet the user's needs. In other words, batteries age and die (or at least, start to give unacceptably low performance). This process consists partly of a time driven element (calendar fade), and a usage driven element (cycle fade). A common criticism of 3rd Party batteries is that their service life is shorter than that of the OEM battery.

CALENDAR FADE
Even if you never use the battery, it has a limited calendar life. As a general rule, the capacity of an unused battery will reduce to about 80% by the time it has reached two years of age. However, because you are probably using your batteries, rather than keeping them in extended storage, cycle fade (which accompanies battery usage), will be of more interest to us.

CYCLE FADE
A battery's charge retention steadily declines through successive usage cycles over a period of months or years. One whole cycle refers to one charge period plus the following discharge period. The typical test condition is fully charging at 0.5C to a voltage of 8.4V, and then, discharging at 0.5C to a voltage of 6.0V. The cycle life is the number of cycles which can be made before the discharge falls below a set percentage of the rated capacity. A reasonable expectation (for mirrorless camera batteries), would be about 80% capacity after 300 cycles, and 70% capacity by 500 cycles.

It is difficult to assign a time-frame to cycle referenced usage, since this will differ according to the particular photographer using the battery. Fujifilm states that the NP-W126S battery should be good for at least 300 cycles. On the basis of this 300 cycle expectation, if you charged and ran down your battery every day for six days of every week, the battery would barely last one year, before hitting the 80% mark. However, a photographer with such heavy battery usage, is likely to have more than one battery, (with some batteries being charged while others are in use), so that in practice, you may still find that it takes more than 2 years for an individual battery to reach 300 cycles.

The 300 cycle specification does not mean that at 300 cycles, the battery is "dead"; rather, it means that by 300 cycles, because the battery only retains 80% of its original capacity, it may no longer be performing up to the photographer's expectations. For example, on a shoot that could normally be completed on one fully charged battery, you may now have to do a battery change before the end of the shoot, if the battery is showing signs of cycle-fade.

BENCHMARK
As a service life benchmark, an OEM Fujifilm battery can be expected to give four or five years of service. About two years of primary service (top capacity and performance, suitable for professional needs), and about two to three years of secondary service (declining, but still good, capacity and performance, suitable for more casual photography, or for back-up use). The service life has effectively ended when the battery gives an unacceptably small number of shots, or it just won't hold a charge. When comparing 3rd Party batteries to OEM, we should frame the comparison within the context of the four to five year lifespan of the OEM batteries.

DELIBERATION
Because battery ageing takes place over a period of at least months, it is not something that you can assess instantaneously, or within a short period of the purchase time. You mainly get this information from your own extended usage experience, or that of others. Comments such as "I have been using this battery for a while, without any problems", are unfortunately, so imprecise as to be virtually useless. More objective feedback with reliable numbers (such as months of service, charges per month, and typical number of shots per charge), from other battery users (either colleagues, or via on-line forums), is invaluable in making a pre-purchase assessment. Again, the question is whether the 3rd Party battery can equal (or perhaps even better) the long service life of the Fujifilm OEM battery.

[ 9 ] CONTROL CODES

Control codes (or production codes) are an important part of battery manufacturing quality assurance. Although there may be codes on internal components of the battery (and therefore, not visible to the user), the codes of interest to the user, are any codes marked on the case of the assembled battery.

These sequences allow the manufacturer to track such details as a battery's date of production, production batch, production line, region of destination, or other pertinent information. If a battery is found to be faulty, with a systemic fault that may affect other batteries of the same production batch, these codes are necessary to be able to distinguish affected batteries from the rest of the production cohort.

RECALLS AND ADVISORY NOTICES
Control codes allow after sales follow up, in cases where a product batch has been found subject to quality issues. These do happen. In February of 2012, Nikon initiated a voluntary replacement scheme, for specific batches of their EN-EL15 batteries, due to the possibility of the the battery overheating, and the exterior casing becoming deformed. Such a replacement scheme is only possible, because batteries from the affected production batches can be identified, by way of their lot numbers.

PRODUCTION DATE
A cheap battery may turn out to effectively be an expensive battery, if you find that you purchased stock that is several years old. Even though it has never been used, it may now be past its prime, due to calendar fade. Lithium-ion batteries are at their best for about two years, post manufacture. After that, a decline in performance starts to become apparent. With many 3rd Party batteries, their age since date of production is generally not discoverable, and we have to make assumptions about age based on their purchase date. A feature of the Fujifilm OEM batteries is that their production date can be precisely determined.

This is useful, not only for projecting future performance expectation, but also for avoiding overly-old batteries at time of purchase. (Taking into account distribution and logistics matters, up to several months past the production date would seem an acceptable age for a "fresh" battery).

DELIBERATION
Control codes can contribute to our level of confidence in the battery, and as such, can deliver a user-experience type advantage. It affects how you feel about your new battery acquisition in terms of confident expectation that this is a quality battery, with a probable long service life. If it is important to you to ensure that newly purchased batteries are as fresh as possible, and if you can inspect the battery before purchase, OEM batteries, because they can be accurately dated, may have an advantage. Without the ability to date the battery, 3rd Party batteries may have a degree of chance attached to their purchase, especially if the vendor has a low or unknown turnover rate.

[ 10 ] WARRANTY

There are two different warranty issues. One is the warranty on the battery. For the OEM battery, this may only be several (maybe 3) months, depending on your regional Fujifilm office. Among the 3rd party providers, you can find a few that offer a clearly spelled out warranty (in one case, 3 years). But for most of the 3rd Party providers (particularly unbranded, or little know brand batteries), there may be virtually no warranty. The battery's vendor might replace an early failure battery, but mainly as a matter of goodwill, and to preserve good feedback.

CAMERA WARRANTY
The other warranty issue is to do with how using a particular battery could affect the warranty on the camera. If a camera, still under warranty, was damaged due to a defective battery, the camera company would rightly be concerned with the question of whether the battery was an OEM or a 3rd Party battery. Firstly, if the battery was the cause of the damage, the responsibility for the damage should lie with the battery manufacturer, who would not be the camera company, in the case of a 3rd Party battery. Secondly, the camera company typically abnegates responsibility in cases of "failure to follow operating instructions", including the instruction not to use any batteries other than the OEM battery.

For some people, buying an OEM battery, is like paying extra to get insurance, so that they won't have to cover their own repair costs if a defective battery induced problem should occur, while the camera is under warranty.

EXPIRY OF WARRANTY
The warranty issue could be considered a short term, and a transitory issue. Eventually, the warranty on the camera expires, and It could be argued that, if the camera is out of warranty, then the warranty issue is not relevant. This would generally be considered a reasonable position to take. However, if you up-grade your camera regularly, then long term considerations can make this situation a little more complex.

BATTERIES CAN SPAN CAMERA GENERATIONS
Of course, a new camera comes with a new OEM battery, so there is no problem there. However, many people require more than one battery for their camera. As an example, for my X-T3 camera, I currently have 5 batteries (all of them OEM): one in the body, two in the grip, and two spares. One was supplied with the camera, but the other four, still working well, were taken from my older X-T2. The point is, batteries can span camera generations. So even when the X-T2 went out of warranty, there was an advantage in purchasing OEM batteries as spares, because they later ended up being used in a new "under warranty" camera again (the X-T3).

INSURANCE
If you are a professional photographer, who has all of your photographic gear insured, you can effectively bypass the warranty issue, if your policy is comprehensive enough to cover battery failure, or battery instigated camera damage.

DELIBERATION
Statistically, most people will never have to make a warranty claim on their Fuji-X camera. Once the camera is out of warranty, this may not be an issue at all. You may be willing to take the risk of using a battery that, in the perhaps unlikely event that it damages your camera, could lead to you having to pay the repair (or replacement) costs. The probability of this not happening, is on your side. You may consider this an area where, although it's nice to have the security, you are willing to save some money, by taking the chance that this issue does not ultimately eventuate.

[ 11 ] RELIABILITY

Reliability refers to a high level of confidence in a battery, both in terms of safety, and general operability. Battery reliability may be of critical importance to professional photographers, as well as other photographers who are working at a high level of camera expectation, or high rate of workflow. But it can also be relevant to any photographer who would like to have a trouble-free photographic experience. Unreliability can manifest as safety problems or service problems.

SAFETY RELIABILITY
Safety reliability is concerned with the battery's ability to handle various types of accidental abuse. Assurance testing typically covers electrical, thermal, and mechanical types of abuse.

When subjected to these types of abuse, the battery should have a high level of resistance to combustion or explosion, or if the battery does combust/explode, the effect should be relatively contained (ie, not releasing flaming particles, or high velocity projectile fragments).

COMPLIANCE
Certification and conformity guarantee that the battery type has been tested up to appropriate standards. The Fujifilm OEM batteries comply with applicable standards for user replaceable batteries. The current battery displays 5 compliance symbols.

The battery may also be compliant with other standards, which do not mandate display of a symbol or marking (for example, transport of dangerous goods by air, under UN/DOT 38.3). Internally, the OEM battery shows compliance with relevant standards. For instance, the protection circuit board states compliance with UL 94V-0 Flammability Test, as well as carrying the UL Recognized Component mark ("backward R" U).

3rd party batteries frequently carry only the CE marking (which can be self-assessed), or no compliance markings at all.

FAKE CERTIFICATION OR CONFORMITY
Sometimes the certification or conformity markings (particularly the CE mark), of 3rd Party batteries are fake. An un-branded battery could not achieve proper CE conformity, because CE compliance must always be traceable, and someone must ultimately be accountable. Traceability facilitates market surveillance by the regulating authority, and makes the identification required for enforced withdrawals and recalls, possible. For CE conformity, the manufacturer needs to hold documentation, including a Declaration of Conformity (DoC), as well as a Technical File, which is a dossier fully documenting the evidence relating to the product's compliance with the applicable safety standards. Obviously, such documentation (even if it does exist), is not open to scrutiny by the regulating authority, if the manufacturer is anonymous, or cannot be contacted or located. The product is also required to bear a batch, type, serial, or model number, for identification. The following battery lacks the basic features required for traceability. (In this case, it doesn't even state the country of origin).

Other batteries give away their sham compliance by using an incorrect form of the CE mark. The true CE mark has a significant space between the two letters, due to the overlap of the two "construction" circles, underlying the design:

However, on the following 3rd Party battery, the spacing is reduced, and the middle bar of the E letter, is longer than it should be.

This look-alike symbol is sometimes referred to as the "China Export" mark. In terms of indicating conformity to safety standards, it has no real meaning.

SERVICE RELIABILITY
Battery reliability is not only concerned with safety, but also with the ability to complete the task at hand, without undue delays (such as unscheduled battery changes), erratic equipment behaviour, or data losses. Service problems can be: low shot count, "flat-without-warning", high self discharge, short lifetime, and irrecoverable sudden battery failure. Battery failure (including full depletion without sufficient warning), can result in missing a key shot, or sudden stopping of a video sequence without the proper termination and shut-down procedure, resulting in possible data corruption, or even complete loss of the video file. Furthermore, there may be unforeseen events, which will push the camera and battery to the limits of endurance, and we would like to have confidence that the battery can handle these situations.

RELIABILITY OF THE PHOTOGRAPHER
For some professional photographers, it may be the case that use of OEM batteries is effectively mandatory. For instance, the risk of batteries failing during a shoot with no possibility of re-shoots or second chances (the ceremony part of a wedding shoot, or fast paced sporting events photography), could make the selection of battery type virtually non-discretionary. Your clients have a reasonable expectation that you have exercised due diligence in ensuring that their photographic brief can be fulfilled. Missing a key shot, because a battery, which was chosen on the basis of its lower cost, failed without warning, falls below the best standards of professionalism. If you happen to live in an ultra-litigious society, the fact of having used your equipment according to the directions of the camera's manufacturer (including, using the specified battery), may form an important part of your defense, in case of a law suit brought against you, over a photographic brief marred by misadventure, either through failure to capture non-repeatable moments and events, or through accident or injury due to battery initiated fire or explosion. For professional photography, a higher price paid for OEM batteries might just be considered one of the costs of running the business.

TENDERING FOR CONTRACTS
Some professional photographers have experienced that when tendering for the contract of a video or photographic project from a government department, or a major corporate entity, contractual expectations for the tender may include submitting copies of recently developed risk assessments that are relevant to the tender, as well as evidence that equipment is maintained in accordance with manufacturer/legislative requirements. Strictly speaking, equipment needing to meet compliance with safety standards, would also include user replaceable lithium-ion batteries, and it may be that only the OEM battery is able to meet this requirement.

DELIBERATION
When exploring the critique of reliability, there are issues that are very significant for professional and highly specialised amateur photographers, that might not hold the same significance for the casual, recreational photographer. If we think of confidence in our equipment as, "having a good feeling that something bad won't happen", we have to recognise that the "something bad" has a different significance for the high-level pro (where a botched brief or battery-caused injury, could mean lawsuits, loss of reputation, or even bankruptcy), and for the specialist amateur (where it could mean the failure of a long planned and expensive project or expedition), compared to what it means to the casual photographer (where a missed shot may only be a transitory annoyance, and simply written off as bad luck). How important this issue is to you, only you can decide. Once again, you might ask, is the benefit of a high level confidence in equipment reliability, worth the extra battery cost?

[ 12 ] ULTIMATE VALUE

When I say "ultimate value", what I mean, expressed in a few more words, is "Ultimately, it all comes down to the amount of user relevant Value (not necessarily monetary) delivered by the battery". At the very beginning, we looked at battery price, and the differences between OEM and 3rd Party batteries were stark. In order to justify the higher cost, the OEM battery had better deliver a lot of benefits to the battery user.

This is how I have chosen to present summaries for various battery types, in a very visual way, in order to assist "getting your head around" a very complex analysis. Your methods and conclusions may differ considerably. For a final analysis, I have brought together all of the criteria in a single chart, and further grouped the criteria into the categories of PRICE & VALUE, CAPABILITY & PERSISTENCE, and SAFETY & CONFIDENCE. This represents the personal way that I chose, to compile information about different batteries, for the purpose of producing an overview. You may have a method that suits your needs and preferences better. Please note that the selected criteria are by no means comprehensive, and the individual battery user may be in circumstances where other criteria (for instance, cold climate battery performance), may also be very important.

For the PRICE critique, a lower price scores higher, and its line has the related critique of VALUE at the other end. They are the two poles of the consideration: "How much does it cost, but also, how much do I get, for what I pay?" (For our purposes, the VALUE critique has simply been based on an aggregate of the capability, persistence, safety, and confidence scores).

Another line joins the related critiques of CAPABILITY and PERSISTENCE. Capability simply means the ability of the battery to power the camera, for an acceptable period of time, or for an acceptable number of shots. It means the battery has the capacity required by the photographer, and can deliver the performance required by the camera. Persistence means that the capability that we experience now, is able to be sustained into the future, both short term (low self discharge), and long term (long battery service life).

The third line joins SAFETY and CONFIDENCE. Safety should be relatively self-explanatory. But as well as its practical implications, working within a safe system also affects how we feel, while we work. Together with the "confidence" given by using a battery which is specified for the system, (feelings of) Safety and Confidence, operate in the "affective domain". They can allow us to work with a positive and self assured attitude, rather than from a position of underlying apprehension of possible adversity. (For example "I would like to charge this battery in-camera, but I'm afraid that it might swell and get stuck"). In extreme cases, it could make the difference between photography being a fulfilling endeavour, or a stressful task.

This circular arrangement of the criteria will form the basis for a type of graph, variously known as a spider(-web) graph, or as a radar graph. The use of this graphic display is only intended as a tool for exploring the multivariate nature of battery choice, and is not intended as the graphic proof of a universal best choice battery. First, let's look at:

THE PERFECT BATTERY
This battery (which unfortunately does not exist in reality) achieves top scores on all measures, and cannot be surpassed. It is presented here, simply as an ideal to aspire to.

Apart from its perfect scores, the battery's graphic profile is characterised by a "roundness", showing that the battery addresses all relevant areas of critique, rather than concentrating on some and neglecting others. In terms of a graphic profile, this is the type of result that we would like to achieve.

THE FUJIFILM OEM BATTERY
This battery scores very well on all areas of critique, apart from price. Note that it never achieves full possible scores, in recognition that, in reality, there is always room for further development and improvement.

This would be a very well rounded battery, if not for the high (low scoring) price. The high price is testimony that research and development, materials selection, quality management, and achieving safety accreditations, all come at a monetary cost. You pay a lot, but you do get a lot for it. The question is whether some of those benefits (which you have paid for) are superfluous to you personal photographic needs (for instance, warranty implications, and accurate battery level display). It could be claimed that the price is out of proportion to the value, and this is reflected in the distortion of the shaded area of the chart, deviating from the roundness of the "perfect battery". What do you think?

TOP-TIER 3rd PARTY BATTERY
These batteries are in the highest price-group of the 3rd Party batteries, and are generally highly respected. It is rare to hear bad reports about them. (Note that this group excludes those batteries that have a reputation for swelling, or an overstated capacity).

Safety has been marked down because the battery's lack of thermistor is a compromising factor whenever the battery is charged in a Fuji charger, or charged in-camera. The capacity and persistence, which are the most obvious day-to-day criteria for battery worth, are good. For the price, we get a well rounded battery, and a good solid performer.

LOW COST 3rd PARTY BATTERY
These batteries deliver decent short term operability, at a very competitive price. However, over a longer time frame, their deficiencies begin to show. (Note that a lower capability score may simply indicate smaller internal cells, rather than being a reflection on the cell quality).

Over time, high self discharge, swelling, high cycle fade, and ultimately, short service life may become apparent. The low price is achieved partly through cutting production costs, which is seen along the SAFETY-CONFIDENCE line. Safety can be compromised by, for example, using soldering for terminal connections, rather than welding, and by using adhesive tape as an insulating cell-separator, rather than the specially designed cell-separator of the OEM battery. The graphic profile of this battery type is unbalanced, and very "un-rounded". And yet, for some photographers, this battery suits their photographic needs, without incurring the extra costs of "benefits" that may produce little "real" difference for them. If you have a few of these batteries in your bag, then if one fails or misbehaves, just swap in one of the other back-up batteries. This is a practical type of reliability, achieved at a low cost.

DELIBERATION
I have tried, throughout this exploration of battery issues, to present mainly evidence based information, and avoid too much conjectural discussion. Yet, I am very aware that my analysis of a battery type's worth, may differ from that of another experienced photographer, and I respect the value of the differing viewpoints. I hope that I have given sufficient technical material for the reader to arrive at their own informed judgement about which battery type (OEM or 3rd Party) represents the best choice for their own personal photographic style and needs. There is no universally correct answer, but there is an individually appropriate one.

THE DECISION

That bell marks the end of the final round. You 've watched the battle. You've witnessed the blows. Now it's time to make YOUR decision. Will it be the Fujifilm Champ, or the 3rd Party Contender?

And the winner is . . .

Thanks for reading -

THE GREAT BATTERY BRAWL

[ Last updated: 25 July 2019 ]

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