I just dove into these Li-ion cells and was wondering what precautions I would need to take when using them in multi-cell lights. I just got a hold on about two dozen Keeppower 3400mah cells and after charging them I saw some variations on their voltage, nothing significant about 0.01V . I was wondering what’s the acceptable variance when using say 4/8 cells in a light? also, I found out that the batteries slowly drop off in voltage after a few hours off the charger by about 0.01-0.03V, is it safe to just stick them in the light and use them or do I have to wait for them to level off and re-check their voltage to see if they match?
I would say you want them within .03 volts of each other when you put them in the light, and obviously they need to be same capacity and brand. No need to wait for the voltage to drop, you can just pop them into the charger immediately.
So using eight brand new keeppower 3400’s in lets say a TK75+extension tube would be safe then? or do I need to measure capacity one by one with a hobby charger to make sure they all match?