Battery Unit, Method and Apparatus for Operating the Battery Unit

A battery unit includes at least one string of battery modules and a low-voltage switching unit connectable to multiple low-voltage loads. The battery modules are electrically connected in series. Each battery module includes a plurality of battery cells electrically connected in series. Each battery module includes a balancing circuit with an output port and multiple input terminals connectable to the battery cells of the respective battery module. The output ports of the balancing circuits are connected to the low-voltage switching unit. Each of the balancing circuits is configured to provide on its output port an output voltage with a predetermined voltage value and to extract energy from a selected battery cell or from selected battery cells which are connected to the balancing circuit and to provide the energy at least partly as power supply to at least one of the low voltage loads connected to the low-voltage switching unit.