Batteries
From The Glossary of Digital Photography
The electrical components used to provide the energy to power digital cameras. They produce or store energy through chemical reactions. The name of each type of battery is related to its chemistry. There are a number of choices of batteries today, depending on the size the camera takes. Many digital cameras will take AA batteries, which provide the option of using rechargeable batteries normally, and substituting regular disposable alkaline (actually alkaline/manganese) batteries when traveling and there is no time for recharging. Among the rechargeable batteries are nickel-cadmium (NiCad) and nickel metal hydride (NiMH). The NiMH batteries generally provide better service over the long run. Some cameras will use only custom batteries made by their manufacturer. If that is the case, be sure to have backup batteries when traveling. Because the different types of batteries actually provide different voltages to the camera, cameras may require the photographer to tell it what kind of battery is being used so it can adjust for the different voltage internally. The capacity of the small batteries used in digital cameras is usually related in terms of milliampere-hours, abbreviated as mAh. The rechargeable batteries lose their charge fairly quickly compared to an alkaline type of battery. While an alkaline AA battery can be good for years, rechargeable batteries can lose their charge at rates up to 3% per day. Typical rechargeable batteries can be recharged hundreds of times.
