Patent ID: 8040107

Claim:
A battery charger for a rechargeable battery, comprising: a battery managing unit including a data collector monitoring said rechargeable battery to see whether or not said rechargeable battery is discharged and producing pieces of historical data expressing use of said rechargeable battery, and an analyzer connected to said data collector and determining a tendency of said use on the basis of said pieces of historical data so as preliminarily to determine state of said rechargeable battery to be charged; a charging unit electrically connectable to said rechargeable battery and charging said rechargeable battery; and a charge controlling unit including a determiner connected to said analyzer and said rechargeable battery and monitoring said rechargeable battery to see whether or not said rechargeable battery enters said state, and a commander connected to said determiner and said charging unit and instructing said charging unit to charge said rechargeable battery while said rechargeable battery is staying in said state.