More Upcycled Power Banks

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Here's a quick way to test 18650 lithium-ion cells recovered from laptop battery packs using the simplest power bank enclosure.

Put them on charge to 100% then leave for 24 hours and test with the voltmeter to see which ones are holding 3.7 volts or close to it. I have a bunch of old laptop batteries, all with 6 cells each and hoping to recover 16 usable ones for a monster power bank which can be charged at night on cheap electricity (as a wack experiment really, not going to run the tumble dryer obviously!).

So far, so good, pack charged to 100% from zero in about 7 hours.


Another batch of cells being charged. 


Cells resting waiting to be voltage tested after about 14 days. Any cells holding a charge of 3.7 volts or more are usable and will go into a power bank casing. 

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