Electric supply system for a vehicle

The present invention relates to a system and a method of operating an electrical supply of electrical consumers of a vehicle with an internal combustion engine, with a battery provided in the vehicle, wherein a terminal is provided, wherein the battery via the connection from an external to the vehicle power source is rechargeable, wherein during a first operating phase of the vehicle, in which a state of charge of the battery is above a threshold value, the electrical load of the vehicle are essentially supplied from the battery, wherein, in lowering the state of charge of the battery falls below the threshold a second operating phase of the vehicle starts, wherein in the second operating phase the battery is charged by the generator and / or the electrical load is powered by the generator current.