Hi Morton
I use the Sanyo Eneloop AA batteries (Nickel Metal Hydride) in my Canon flashgun, as I read on a photography forum that they hold their charge more effectively than other NiMH and NiCads.
I used to find that my AA NiCads discharged to the point of being useless if left in the cupboard for a few weeks without being charged.
Sanyo claim that the Eneloops retain up to 85% of their charge even after 12 months.
Cheers
Dennis