Alkaline batteries last the longest, but most consumer tests don't
show a significant or consistent difference in life from brand to
brand, so buy whichever is cheapest or on sale. Alkaline batteries
designed for high-performance use will give you a few more hours of
life for a slightly higher price. If your device uses watch or hearing
aid batteries, use the lithium-ion type.
Rechargeable batteries also perform well, and have the benefit of
reducing environmental toxins and waste. They are slightly less
convenient than disposables, as they take time to charge, and they
require the initial investment for a set of rechargeable batteries and
a recharger. Note: Do not attempt to recharge standard disposable
alkaline batteries; they may explode.
Consumer Reports Report on single-use and rechargeable batteries (12/02)