I use Eneloop batteries. They're great as they have very little idle discharge, so you can leave them on the shelf for months and they're still good to go when you need them.
One more for Eneloop.
Just avoid "lite" versions, these are not for intensive use.
Emil Pozar, http://emil-pozar.photoshelter.com/
|Glass by Hobbyfotograaf|
from High speed photography
|Northern water thrush by APenza|
from A Big Year - birds
|4th of July Outfit by Jack Sofield|
from - Old Age - (Black and White only + A Border)