Power storage system

A power storage system is provided. A control apparatus controls the power storage system to perform a charging mode in which an assembled battery is charged in a first predetermined time period and a discharging mode in which the assembled battery is discharged in a second predetermined time period. A residual electric power amount determination unit detects an amount of one of electric current and electric power currently remaining in the assembled battery. A discharged electric power amount determination unit detects an amount of one of electric current and electric power discharged from the assembled battery during the second predetermined time period. The control apparatus estimates an amount of one of electric current and electric power discharged from the assembled battery during a next second predetermined time period based on amounts of one of electric current and electric power having been discharged from the assembled battery during past second predetermined time periods to obtain an estimated value. A correction control unit controls the power storage system not to perform the charging mode in a next first predetermined time period if the estimated value is less than the amount of one of electric current and electric power currently remaining in the assembled battery.