| 摘要 |
PURPOSE: To eliminate the influence of load fluctuation to surely determine the completion of charge of a battery by finding the attenuation rate of the output current of a battery charger through the measurement of the current in an appropriate period, and comparing the attenuation rate with a set value. CONSTITUTION: In a battery charger 1 having a power supply portion 11 and a charge control portion 12, a charging circuit 111 converts AC 100V into direct current and performs voltage and current control, and the battery 21 of a portable telephone 3 is charged with the current through a charging terminal 3 and via an output switch 112. In that case, the sum of the charging current of the battery 21, that is, the output current supplied by the battery charger 1 and a load current is measured in an appropriate period, and the measured values are stored in sequence and by the required number in the memory of the determining part 121 of the charge control portion 12. Then those measured during load fluctuation are excluded from the measured values, and the temperature of the battery 21 is compensated by a thermistor 14 to find the attenuation rate of the output current. The attenuation rate not greater than a set value is judged as indicating the completion of charge, and then a signal is outputted to the power supply portion 11 to stop charge. |
