Battery pack for selectively setting a high capacity mode having a high charge capacity until a full charge of a secondary battery

摘要

A controlling and computing portion for controlling charge or discharge of a secondary battery comprises an operation mode setting portion for selectively setting a high capacity mode using a first voltage or a long life mode using a second voltage lower than the first voltage, a remaining capacity calculating portion for calculating a relative state of charge from a remaining capacity of the secondary battery and a full charge capacity, a cycle number calculating portion for calculating a cycle number from a calculation result of the remaining capacity calculating portion, and a charge end voltage setting portion for decreasing the first voltage based on the cycle number, and setting the second voltage at a voltage left by subtracting a predetermined voltage from the first voltage in a case where the first voltage becomes equal to or less than a voltage obtained by adding a predetermined value to the second voltage.