Image Number 2 for United States Patent #6828761.
When a battery is in a standby mode, a microcomputer switches to a sleep mode when no charging/discharging current is supplied within a predetermined time and controls a timer to start measuring the standby time of the battery. When a charging/discharging current is supplied, the microcomputer switches to a wake-up mode and controls the timer to stop measuring the standby time. Then, the microcomputer reads the measured standby time. Based on the read standby time, the microcomputer calculates the correction value to correct the currently stored remaining battery capacity value.