Picked up a laptop pack that was old but un used. 2008 dated ur18650fm. Cells were between 2.4 and 3.5 before charge. All jumped to 3.5 once in the charger.
Cells were getting pretty warm while charging. Maybe they are too old?
Which charger are you using and how much Ampere? Older cells have a higher resistance which is an additional factor for getting warm.
If the heat is generated by the cells themselves, they should be tossed out because they have too high of an internal resistance.
If they are getting heated by the charger, it’s less of a problem.
Getting warm in the charger, but it appears they started charging really slow from ~4.0 volts towards 4.2
I’m running them through a charge-discharge cycle, and then going to test the self discharge.
number suggests red sanyos.
this is a common failure mode for them and they should be recycled.
any li-ion that heats at a rate of 1c or less is suspect.
recycle first and ask later.
1C? So an NCR18650B should not get warm at a 3.4A charge rate?
:weary: