I would just use a pack of NiMH or even lead acid rechargeable batteries. They aren't very finicky about how they are charged, in contrast to Li-based cells. In all cases, you need a low voltage cutoff of some sort.
I would just use a pack of NiMH or even lead acid rechargeable batteries. They aren't very finicky about how they are charged, in contrast to Li-based cells. In all cases, you need a low voltage cutoff of some sort.