Mastodawn

More USB-PD cursedness. I really need to figure out what's up with this power bank.

Laptop is an older Thinkpad with the yellow rectangle power connector. The USB-C ports are also Thunderbolt but are not able to charge the laptop (there's no PD sink functionality).

Laptop - phone via USB C-C cable: phone charges
Power bank - phone via same cable: phone charges
Power bank - laptop via same cable: power bank lights up for a second or two then shuts off and does not charge

Power bank - random usb charger from REWE via same cable: power bank charges normally

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too many names 1d ago

@azonenberg That seems like pretty explainable behavior?

USB-C port on your laptop doesn't support USB-PD but does support BC 1.2 for [email protected] / 7W or USB-C Current 5V@3A / 15W.

Your bank probably wants a minimum charge rate and won't trickle charge off your laptop port.

Is the random charger a USB-PD capable charger? Maybe your laptop only supports BC and tops out at 1.5A but the random charger supports full 3A

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Andrew Zonenberg 1d ago

@mikeymikey hmmm so you're think it mandates PD at the input and won't charge on a 500/900 mA source? Possible, it never occurred to me that it might have a minimum charge rate

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Andrew Zonenberg

@mikeymikey laptop port is thunderbolt3 capable though so it'll give a thunderscope enough power to operate (circa 9W iirc)

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Andrew Zonenberg 1d ago

@mikeymikey which seems like it should be enough to charge a power bank at a reasonable rate

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Andrew Zonenberg 1d ago

@mikeymikey i guess the other possibility is that the bank is a PD sink and will not charge from 5V under any circumstances and mandates 9V or higher or something which the laptop won't provide. This was actually the scenario i was thinking was more likely

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too many names 1d ago

@azonenberg that would make sense, assuming your random charger it worked with did support USB-PD

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Andrew Zonenberg 1d ago

@mikeymikey yeah no idea i have no easy way to measure that from a German hotel room

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Andrew Zonenberg 1d ago

@mikeymikey the goal was to have my laptop brick be the only mains powered device on the trip and just charge everything else off it directly via usb or indirectly via the power bank. Didn't quite pull it off

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pera 1d ago

@azonenberg i guess you don't have a type A to C with you? If there is a TV or a wall outlet with USB you could try to confirm that your power bank doesn't charge on BC 1.2 alone (didn't know that was a thing)