I can't help but wonder if there is not a cordless phone battery pack that might actually fit.
I know there are ones that use (3) AAA cells and others that use what appears to be 2/3 "AA". The diameter to work with is 15mm or less. These are all NiMH from what I have looked at. I did order a new CMOS NiMH 3.6vdc pack for $6... I'll do some testing here once it arrives. The idea of putting NiMH or NiCad in parallel is not all that appealing.
