Charge stop point detecting method, charge stop point detecting device, and a battery pack

A charge stop point detecting method comprising the steps of:

• sequentially detecting the voltage and the charging/discharging current of a rechargeable battery;
• detecting a first point when the detected voltage is higher than predetermined voltage and when the detected charging current keeps smaller than predetermined current for predetermined time;
• integrating charged/discharged capacity based on the detected charging/discharging current;
• detecting a second point that is different from said first point based on the integrated capacity;
• and
• deciding to stop charging said rechargeable battery when any of said first and second points is detected, wherein
• if the detected voltage is higher than voltage for detecting the first point, charged/discharged capacity is integrated by adding/subtracting the charged capacity and the discharged capacity, and
• if the integration result shows that said rechargeable battery is totally charged, it is determined whether the absolute value of this integrated capacity is greater than predetermined capacity, wherein
• the second point is detected when this absolute value becomes greater than the predetermined capacity.

A charge stop point detecting device comprising:

• an integrating portion that integrates charged/discharged capacity of a rechargeable battery based on charging/discharging current of the rechargeable battery that is sequentially detected;
• a deciding portion that decides the point for stopping charging said rechargeable battery based on the capacity integrated by said integrating portion;
• and
• a detecting portion that sequentially detects the voltage of said rechargeable battery, wherein
• if the voltage detected by said detecting portion is higher than predetermined voltage, said integrating portion integrates charged/discharged capacity by adding/subtracting the charged capacity and the discharged capacity, wherein
• the charge stop point detecting device further comprising
• a determining portion that, if the integration result obtained by said integrating portion shows that said rechargeable battery is totally charged, determines whether the absolute value of this integrated capacity is greater than predetermined capacity.