BATTERY CONTROL DEVICE, BATTERY CONTROL METHOD, UNINTERRUPTIBLE POWER SUPPLY, POWER SYSTEM, AND ELECTRIC VEHICLE

The battery control device includes: a charge/discharge controller configured to charge or discharge the secondary battery during diagnosis; an open circuit voltage curve acquisition device configured to acquire an open circuit voltage by charging or discharging the secondary battery; and an arithmetic processor configured to estimate a potential of the positive electrode and a potential of the negative electrode from an open circuit voltage curve. The battery control device controls the charge cut-off voltage and the discharge cut-off voltage such that an estimated positive potential does not exceed an upper limit and a lower limit of voltage that are preset.