a vehicle connectable to an auxiliary power unit capable of energizing a pair of fail - safe brakes that arrest rotation of a pair of electric transaxles mounted to the vehicle . each brake has an external connector and requires electrical power to assume a non - braked state that permits free rotation of an electric motor engaged to the brake and incorporated in each of the electric transaxles . the auxiliary power unit having first and second circuits and first and second connectors compatible with the external connectors of one of the brakes .