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| Can lithium ion / lithium poly "recover" after getting weak? |
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| edpalmer42:
Cheap powerbanks don't usually have batteries in series. That would require some form of BMS to keep the cells balanced. It's more common to have them in parallel with a boost converter to get a 5V output. SilverSolder, in your case, the initial 1000 mah charge may have been due to the management chip deciding that only a small trickle charge was allowed. The low current caused the voltage as viewed outside the battery to climb quickly. The charger itself may have terminated the charge. After the first discharge, the cell voltage was still good and the chip allowed a more complete charge. Forgetting a device in a drawer for a long period of time is a common way that the batteries get overdischarged. The management chip itself needs power and, over time, discharges the batteries and then refuses to charge them back up! I have a lantern that was in that condition when I bought it used. The actual cell was just slightly below the cutoff voltage so just poking a bit of charge into it was enough to raise the voltage to the point that the management chip let it recharge. |
| Siwastaja:
--- Quote from: SilverSolder on May 24, 2020, 08:45:36 pm --- --- Quote ---SEI destruction and release of gases alone is a huge issue. --- End quote --- Is this what causes some lithium ion batteries to swell up? --- End quote --- Yes. Overdischarge isn't the only condition to cause it, though. |
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