Apparatus and method for operating an electric unit

The invention relates to a device (1) for operating at least a first electrical unit (2), in particular the sensor module (3), with a connectable to a power source / associated second electrical unit (9), in particular control apparatus (10), wherein the first unit (2) and the second unit (9) through an interface (11) are connected together to provide the first unit (2) by the second unit (9) with power, and to provide information at least from the first unit (2) to transmit to the second unit (9). It is contemplated that the first unit (2) comprises a rechargeable energy storage (6) has, and that a control unit (7) is provided which controls the device (1) such that the interface (11) in a first operating state, only the supplied energy storage (6) with energy from the second unit (9), and transmits information only in a second operating condition.