Originally posted by unixrevolution Since you are going to such lengths to save weight, why not weigh lithiums, NiMHs and Alkalines and see which ones are the lightest?
You need about 5 to 6 volts
and the ability to supply over one amp of current at that voltage. If you reduce capacity, the voltage will sag more under load, so you'll get less half the number of shots from half the battery capacity (probably a lot less).
Forget alkalines. You won't get any reasonable number of shots from them. They're for emergency use only.
If you're only concerned about weight, use Lithiums. AA Energizer Ultimate Lithiums are 14.5 grams each, or 58 grams for four. This saves 50 grams (1.8 ounces) over Eneloops.
If you want rechargeable, use Eneloops. AA Eneloops weigh 27 grams (108 grams for four).
If you really, really want rechargeable and less weight, here are two things you could try. First, Sanyo make a battery called
Harmolattice which is a low cost, half capacity version of the Eneloop. It only weighs 19 grams apiece (76 grams for four), so not as light as the lithiums but rechargeable. I have no idea how well the voltage would hold up, and you'd save less than an ounce over Eneloops. They might also be hard to buy. A second possibility would be to use three PowerGenix NiZn AA batteries and a spacer. Nominal 1.65 volts per cell by three = 4.95 volts. Weight is 25 grams each by three = 75 grams, plus the weight of the spacer, making total weight savings less than an ounce.