An ampere-hour (symbol A h or A·h, sometimes abbreviated as Ah) is a unit of electric charge. One ampere-hour is equal to 3600 coulombs (ampere-seconds), and is the amount of electric charge transferred by a steady current of one ampere for one hour. The ampere-hour is a unit frequently used in measurements associated with electrochemical process such as electroplating and electrical batteries. Although it is not a direct measure of the energy in a battery (like the joule (J) or watt-hour (W h)), it is a common rating of how long a battery will last (or in the case of a rechargeable battery, how long it will last when fully charged). The commonly seen milliampere-hour (mA h) is one-thousandth of an ampere-hour and is equal to 3.6 coulombs.
