Translations:Energy storage/22/en

The state of charge (SoC) of a battery is the total amount of its storage capacity that remains available for use. It is important for system users to understand how much energy remains for use to avoid damaging the battery by withdrawing too much energy. For example, if 25% of the capacity of a battery has been used, then its state of charge will be 75%. A fully AGM battery will have a voltage of around 12.8 V and an empty battery will have a voltage of around 10.5 V. If a battery is being discharged, its voltage will drop and if it is being charged its voltage will increase. In a PV system, which is constantly being charged and discharged, this can make it difficult to get a proper state of charge measurement from voltage. Nonetheless, many small-scale battery-based systems do not rely on a shunt and users commonly use the voltage of the battery bank as their only guide. To get an accurate measurement of state of charge there are three options: