Technologies and techniques for charging a high-voltage battery of an electric drive of a vehicle, in which electrical power is transmitted from a low-voltage on-board electrical system of the vehicle to the high-voltage battery, and, to aid starting of the vehicle, electrical power is transmitted from a separate external unit to the low-voltage on-board electrical system of the vehicle and is transmitted from the low-voltage on-board electrical system to the high-voltage battery. The present disclosure also relates to a related power transmission system.