A battery charge system includes an on board charge module, a high voltage battery pack unit and a controller. The on board charge module includes a power conversion device, a switching unit coupled to the power conversion device, and an electrothermal element coupled to the switching unit. The power conversion device includes an AC/DC converter and a bidirectional DC/DC converter. The AC/DC converter has an input terminal coupled to an AC terminal, and an output terminal coupled to an input terminal of the bidirectional DC/DC converter. The high voltage battery pack unit includes a first switching element and a high voltage battery pack. The high voltage battery pack is coupled through the first switching element to an output terminal of the bidirectional DC/DC converter. The controller is coupled to the power conversion device and the switching unit, and is configured to control the power conversion device and the switching unit.