Nickel-metal hydride (Ni-MH) rechargeable batteries, have a higher energy density than their Nickel Cadmium (Ni-Cd) equivalents, and are more easily damaged by excessive charge or discharge rates. They last 300 to 500 charges. They are suitable for use in digital cameras.
Ni-Cd batteries have the edge for devices with higher drain such as power tools. They can overheat if overcharged. They last about 500 recharges.
Batteries have a rated capacity abbreviated as "C" and measured in amp-hours (Ah). It is usually measured at a discharge rate of C/10 at 20°C. (the capacity being dependent upon the discharge rate and temperature). For example a battery with a capacity of 5 Ah can supply 250 mA for 20 hours before dropping below its rated voltage.
|D||1.2 to 5|
|C||1.1 to 2.8|
|AA||0.5 to 2.9|
|AAA||0.18 to 0.22|
The capacity of NiMH batteries is dependent upon their physical size.