Abstract: When it has been determined according to a voltage detected by a voltage detecting unit 31 that a voltage detection line 23 between a focused-on battery 21 and the voltage detecting unit 31 has been broken, operations of each of switches 22 are controlled to separate a battery module 2 that includes the voltage detection line 23 from a power supply apparatus 1. When it has been determined according to the voltage detected by the voltage detecting unit 31 that the focused-on battery 21 has been overcharged or overdischarged, power input to, or output from, every battery module 2 is limited.

Abstract: When it has been determined according to a voltage detected by a voltage detecting unit 31 that a voltage detection line 23 between a focused-on battery 21 and the voltage detecting unit 31 has been broken, operations of each of switches 22 are controlled to separate a battery module 2 that includes the voltage detection line 23 from a power supply apparatus 1. When it has been determined according to the voltage detected by the voltage detecting unit 31 that the focused-on battery 21 has been overcharged or overdischarged, power input to, or output from, every battery module 2 is limited.

Abstract: Voltage-change convergence time (?) taken from the termination of charging and discharging of a secondary battery until the convergence of change in open-circuit voltage is measured in advance for each combination of the state-of-charge of the secondary battery at a charging and discharging termination time and the temperature of the secondary battery at the charging and discharging termination time. When the charging and discharging of the secondary battery is terminated in actual use, voltage-change convergence time (?) corresponding to the temperature and the state-of-charge based on the integrated current value at the charging and discharging termination time is selected and the selected voltage-change convergence time (?) is applied to a voltage characteristic formula.