Charging
The process by which a battery is supplied with energy by a charger or the generator (GEN) in the car. During charging, the lead sulfate in the plates is converted back to pure lead on the negative plates and to lead oxide on the positive plate. Water is consumed, sulfuric acid is formed and the density of the acid increases.
This reaction can be written
2 PbSO 4 + 2 H 2 O --> PbO 2 + Pb + 2 H 2 SO 4
The state of charge is expressed as the amount of electrical energy that is stored in the battery at any given time, in relation to how much energy can be stored in a fully charged battery. The state of charge is listed as a percentage of full charge. This is the "State of Charge", SOC.