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ampere-hour (Ah)
The quantity of charge transported by an electrical current in a given amount of time. It is the current time product at any level of current (Q = I × t). The coulomb is defined as 1 ampere-second, so 1 ampere-hour (Ah) would be 3600 A·s or 3600 C.
Most batteries are rated in Ah. A modern AA alkaline cell is rated at about 2.5-2.8 Ah (at the rate 100h rate). Battery capacities can be very sensitive to discharge rate and the characterizing rate will be given by the manufacturer. Nickel-cadmium and nickel metal-hydride cells, for example, are typically characterized at a 5h rate; sealed lead acid cells are typically characterized at a 20h rate. At different discharge rates, the Ah rating will be different.
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Thanks to Charles Watson for contributing this entry.
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