| 摘要 |
A control/calculation unit for controlling the charging and discharging of a secondary battery has: an operation mode setting unit for selecting and setting a high capacity mode at a first voltage or a long life mode at a second voltage lower than the first voltage; a remaining capacity calculation unit for obtaining the discharge capacity of the secondary battery and calculating a relative state of charge from the discharge capacity and the full charge capacity; a cycle number calculation unit for calculating the number of cycles from the calculation result of the remaining capacity calculation unit; and a charge stop voltage setting unit for reducing the first voltage according to the number of cycles and for, when the first voltage becomes less than or equal to a value obtained by adding a predetermined voltage to the second voltage, setting the second voltage to a voltage obtained by subtracting a predetermined voltage from the first voltage. This makes it possible to precisely obtain the relative state of charge of the secondary battery in accordance with the operation mode of the secondary battery and, moreover, even when the operation mode is changed. |
