A dual-mode charger circuit includes a first charge circuit and a second charge circuit connected in parallel between a power source and a battery, to charge the battery under a slow charge mode and a quick charge mode. A central processing unit detects a capacity of the battery and determines whether the detected capacity exceeds a predetermined capacity, and outputs a mode control signal according to the determination. A mode switch circuit switches the second charger circuit on/off according to the mode control signal. When the second charge circuit is off, the battery is charged under the slow charge mode, and when the second charge circuit is on, the battery is charged under the quick charge mode.