this post was submitted on 09 Oct 2023
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My current means of powering things is USB rechargable batteries. I have a about five of them that range between small 3000-5000mah ones to a big 20000mah interstate battery jump starter pack. Is there a device that lets me add all their power together into a centeral power source so I don't have to keep swapping them out?

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[–] Zak 18 points 1 year ago (3 children)

It's probably not possible to do that safely because USB power supplies aren't just dumb batteries. They actively communicate with the device receiving power about how much current the device wants, and should only supply 500mA if they fail to do so.

USB-A ports aren't supposed to receive input power, which is effectively what would happen in that arrangement after a powerbank shuts off to prevent over-discharge of its batteries. The resulting behavior is, as I recall unspecified and might result in damage to the powerbank. Worse, it could interfere with the over-discharge protection and damage the batteries. Charging damaged Li-ion batteries is bad, where bad may include fire, explosion, and/or emission of toxic gas.

[–] testfactor 5 points 1 year ago

Yeah, I should work on my reading comprehension.

I deff read the prompt as having a bunch of rechargeable AA style Li-ion batteries, and how to utilize them without having to swap out to a new pair or whatever.

Deff don't want to do this with a bunch of disparately sized smart batteries providing power over USB. Very different problem.

[–] Smokeydope 2 points 1 year ago

Thank you for the great reply!

[–] [email protected] -1 points 1 year ago (1 children)

You can still just crack open the banks and wire the cells together in parallel or series (depending on your needs), then hook them up to one of the controllers. I bet they're just a bunch of 18650s

[–] Zak 4 points 1 year ago

Sure, but you probably shouldn't build a DIY battery pack out of salvaged 18650s of varying brands, capacities, and conditions unless you really know what you're doing because that's dangerous if you get it wrong.