A charger device is configured with electric conducting devices corresponding to electric conducting contact points of a battery. The electric conducting contact points are correspondingly associated with the charger device, a detector device and an automatic switching device. When the charger device is connected to the battery, the detector device determines size of charge current, and when the detector device determines that the charge current has not reached a set value, then the automatic switching device switches a normal charge mode to a boosting charge mode. The detector device stops the charger device from charging if the battery has already been charged for a predetermined time but has not reached a set value, and a display device displays that an abnormal state has occurred, thereby enabling the charger device to achieve the objective of providing good charging effectiveness and functionality to detect abnormalities when connecting to a battery.