BATTERY CHARGING METHOD AND BACKUP POWER SOURCE PERFORMING THE SAME

摘要

PROBLEM TO BE SOLVED: To charge a battery at a constant current according to a charge mode without increasing the power source capacity of an AC/DC converter. SOLUTION: A backup power source 300 comprises an AC/DC converter 101, an DC/DC converter 102 which converts a DC voltage outputted from the AC/DC converter 101 into a prescribed voltage, and a battery 209 which takes in a current from the AC/DC converter 101 for charging. The threshold current value (b) of the AC/DC converter 101 and a battery charge current value (e) in a quick charge mode or a slow charge mode for the battery are set at circuits 220 and 204. The current value (a) of the DC/DC converter is detected. The chargeable current value (c) for a battery which is obtained by subtracting the current value (a), coming from the DC/DC conversion part, from the threshold current value (b) is compared to the battery charge current value (e) set in the mode. A battery is charged at the lower value of both current values. COPYRIGHT: (C)2004,JPO