Just got my hands on a new, well 2014 NOS Lenovo 68+ pack. This is a 6 cell pack (3 series 2 parallel) li-ion pack made of 3300mAh 18650s. Unfortunately it's dead and zero volts because it's been sitting there for 5 years. Seller is sending another one out (tested) but before I throw it in the trash, I thought I'd do a post mortem. Looks like the low voltage disconnect has kicked in. Hmm, wonder if I can give it a kick?
I cracked open the edge of it (it is just clipped together and have access to the battery contacts. Each parallel pair is reading 2.78V, total 8.35V which is perfectly balanced and not totally FUBAR but under voltage so I assume the BMS has kicked in and disconnected the cells.
I don't have a suitable dedicated charger for this and have no li-ion charging experience. Two questions:
1. Is it ok to stuff a bench supply across it set to 3.8V per cell (total 9V) set to 500mA to charge it?
2. What's the chance the BMS on the pack will come back to life at X volts and start working again?
I'm going to monitor it carefully while I'm doing this.
If it doesn't work I'll probably recycle the cells which appear to be good and build a pack for my FT-818ND