Abstract: A toggle electrode disposed on the bottom end of a battery assembly. The toggle electrode includes a rotating shaft and a toggle. The battery assembly includes a negative terminal of an input end soldered on the rotating shaft and a battery. The rotating shaft is connected to the toggle. The toggle is rotatable around the battery to contact or not contact the negative terminal of the battery. When the toggle is not in contact with the negative terminal of the battery, the battery is removable for replacement. The toggle is in contact with the negative terminal of the battery for electric conduction.