Electric charge of a battery
Electric charge that is stored in a battery is normally expressed in Amp-hours or Ah for short. In electrical engineering, we normally use coulombs as a unit for electric charge. For batteries the unit Amp-hour is more appropriate because it tells us how long our battery can provide the current.
Exercise:
A driver forgets to turn off the lights. The 12V battery has a capacity of 60Ah and is 70% charged. The parking lights include the 10W license plate light, two 4W side marker lights, and two 4W taillights.
Assuming a linear discharge rate, how long will it take for the battery to reach 10% charge?