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 charged 12 V AGM battery will have a voltage of around 12.8 V and empty it 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, users of many small-scale battery-based systems have no other option but to use the voltage of the sysetm as a guide. To get an accurate measurement of state of charge there are three options: