I bought an ultra-cheap digital camcorder the other day for some experiments, and it uses a rechargeable 3.6V, ~1000mAh Li-Ion battery type referred to as "NP-60". I'm not sure if this is actually the battery model, or the model# of the (Fuji) camera for which the battery was originally designed, but I suspect the latter.
Anyway, there is a healthy aftermarket for this particular battery model - it's apparently used in all kinds of el cheapo cameras and such
- and you can buy the batteries retail for as little as $4 for a
1200mAh version. It's small and exceedingly light and would be an interesting choice for some homebrew projects.However - is there a reference charger circuit for this battery? I haven't been able to find one through Google searches. It seems to be a very simple pack, with only +, - and thermistor terminals. Ideally I'd like a full gas gauge type application, but I'd settle for a simple fast charger.