Kit Bashir

This is the 100 Ampere-Hour battery I made for my car fridge. It's features are
* Lithium-Iron-Phosphate cells, which are about half the volume and 1/3 the weight of lead acid. I used 4 x 100AH cells.
* A 100Amp rated battery management system (this is overkill, given a fridge only draws about 8A)
* A boost battery charger that can charge the battery from 12v.

The battery charger is configured to have a voltage cut-off lower than my alternator voltage, so that it only charges the battery when the car is running. The charge current limit is set low enough to allow plugging it into a cigarette socket, which means you can have a dual-battery system with no modifications required to the vehicle.

If I was doing it again (and I did, I made a second 50Ah version) I would use a battery management system with bluetooth, which allows monitoring the state of the battery from an app on your phone.

Mar 26 at 2:46amWeb
Show threadPaul FenwickMar 26

@Unixbigot : That's rad!!

What is the max one can pull from a cigarette lighter socket, anyway?

Show threadKit BashirMar 26
@pjf The manual for my (late) land cruiser says do not exceed 10A total from all the sockets.
Show threadDaniel CarosoneMar 26
@Unixbigot somewhere on my list of back-burner projects is to do basically this, as a long thin series of prismatic cells to fit along the otherwise mostly wasted space at the bottom of the cargo barrier. The present 100Ah battery box is a bit awkward for luggage space.
Show threadkauerMar 26
@Unixbigot You are clearly a very clever sausage; I'm envious. Speaking of batteries, did yelling at your car help?
Show threadKit BashirMar 26
@kauer It's been on charge for 3.5hrs now, battery is up to 13.2 volts which I interpret as "back from the dead". Haven't tried starting it because the battery is disconnected while charging.
Show threadisolMar 26

@Unixbigot

Re: monitoring, I've got a sub-$20 gadget from AliExpress to keep an eye on my car battery, as I rarely drive now.

Just check on my phone every couple if days to see if it needs a charge.

Show threadKevin Neely Mar 26
@isol @Unixbigot if you don't drive often, wouldn't it make more sense to be proactive with a trickle charger than reactive with an IOT monitor?