I had a few old ThinkPad batteries lying around. They were big, bulky and not holding much of a charge. Inside those were standard 18650 Li-ion battery cells. I have two TOMO M4 power banks around, and they are fantastic for reusing these old 18650 battery cells inside them. You can even mix and match cells without a worry because they are individually addressed, meaning that any issues with battery charge levels and voltages differing between cells are not a concern. Unfortunately the TOMO M...
