An ampere-hour or amp-hour (SI symbol A·h or A h; also denoted Ah) is a unit of electric current over time, equal to the charge transferred by a steady current of one ampere flowing for one hour, or 3600 coulombs. The ampere-hour is frequently used in measurements of electrochemical systems such as electroplating and incorrectly, the 'capacity' of electrical batteries (a battery constituent material's specific capacity is commonly expressed in mA·h/g). The commonly seen milliampere-hour (mA·h or mAh) is one-thousandth of an ampere-hour (3.6 coulombs). This is commonly used for marketing purposes...