I scored some free LiMN batteries from two dead ebike battery packs. After combining good cell groups from the two packs together to create an OK 32v pack (for the go-kart) I had enough cells left over to make a new battery pack for my old NiCad drill.
I put 8 cells in in 4 groups of two to make a 16v (fully charged) pack. I doesn't have a BMS - so there's no cell balancing at present, and there's no low voltage safety cutout.
I've got a BMS on order, but in the meantime I just put a simple micro-voltmeter onto it so I can see what's going on. And there's a rocker switch on the bottom so the voltmeter only turns on when the drill is picked up.