There are several kinds of rechargeables and each has its own characteristics. While not the most exciting subject, you should know how your batteries work and how to dispose of them when they no longer work properly.

Nickel metal hydride (NiMH) batteries are the most popular batteries for digital camera use because they are rechargeable, nontoxic, and relatively inexpensive. Since they're designed to be used with power-draining equipment, they can offer you more pictures per charge than other types of batteries. According to one manufacturer, NiMH batteries can last 40 per-cent longer than the same size NiCd battery. In digital cameras, NiMH batteries can typically run three to four times as long as an alkaline battery from a single charge.

NiMH batteries are also preferred because they don't have problems with memory effect. Other rechargeable batteries have shorter life cycles if they are recharged before their power fully runs out. Made from nontoxic materials, NiMH batteries are more environmentally friendly than other types of batteries. Battery retailers recommend NiMH batteries for use in digital cameras.

Li-Ion (lithium ion) batteries are one of the newer types of rechargeable batteries. They last about twice as long as NiMH batteries, they don't lose their charge as quickly when stored, and they do not have any memory-effect problems. The downside is that they are harder to find and cost more than other types of rechargeable batteries.

NiCd (nickel cadmium) batteries are the most widely used type of rechargeable household battery for portable devices such as digicams, radios, laptop computers, and cellular phones. You can recharge them quickly, and they last for hundreds of charge cycles. NiCd batteries perform well in low temperatures, but they do have a problem with memory effect. Cadmium is an expensive and toxic metal. Consequently, producing NiCd batteries is expensive, as is disposing of them. To combat the increased costs, some manufacturers are actively recycling components of NiCd batteries.