Abstract: A device and a method of using the device in an electric drive system, particularly in a hybrid drive system of a motor vehicle. The device has at least a first and second battery system, connected in parallel, where their load outputs are connect to a common load output. Each battery system has an energy storage and a pre-charging circuit which is linked to it such that, by way of an output of the pre-charging circuit, the load output of the battery systems is created. The load output of each battery system can be connected or disconnected by way of the pre-charging circuit at the common load output. The common load output is energetically linked directly to an input of an inverter of the device by way of an intermediate circuit capacitor.