US Patent 9525300 Electricity storage system

An electricity storage system includes: an electricity storage unit (10, 11) that is subjected to charging and discharging; a voltage sensor (20, 20a) that detects a voltage value of the electricity storage unit; and a controller (30) that terminates the charging of the electricity storage unit when the detected voltage value reaches a charging termination voltage value. The controller calculates a voltage drop, which is associated with interruption of constant current charging, on the basis of the detected voltage value while the constant current charging is performed in the electricity storage unit, and sets the charging termination voltage value in accordance with the amount of voltage drop.