Patent ID: 8508192

Claim:
A battery pack comprising: a rechargeable battery; and a controlling/calculating portion that controls charging/discharging operation of said rechargeable battery, wherein said controlling/calculating portion comprises: an operation mode setting section that selects a high capacity mode in that the maximum charging voltage of said rechargeable battery is limited to a first voltage so that the fully-charged capacity of said rechargeable battery can be higher, or a long life mode in that said maximum charging voltage is limited to a second voltage lower than said first voltage so that the cycle life of said rechargeable battery can be longer; and a remaining capacity calculating section that acquires a discharged capacity of said rechargeable battery based on a discharging current and a discharging time or a discharging current and a battery voltage of said rechargeable battery, and calculates a relative remaining capacity of said rechargeable battery based on the discharged capacity and the fully-charged capacity of said rechargeable battery, and wherein said remaining capacity calculating section employs the rating capacity or a learned fully-charged capacity of said rechargeable battery as said fully-charged capacity when one operation mode of said high capacity and long life modes is selected, and employs a capacity obtained by multiplying said rating capacity or learned fully-charged capacity by a predetermined factor as said fully-charged capacity when another operation mode is selected.