SECONDARY BATTERY SYSTEM

There is provided a secondary battery system which converts direct current power supplied from secondary batteries (B1 to B3) into alternating current power by power converters (INV1 to INV3), and supplies the converted power to an electric power system on a load side, the secondary battery system including a control apparatus (1) that stops operating the operating the power converter and starts operating the stopped the power converter when a residual stored power level of the secondary battery corresponding to operating the power converter becomes to be not greater than a predetermined rate of a residual stored power level of the secondary battery corresponding to stopped the power converter.