Power supply system for an electric vehicle, comprising a plurality of stacked battery cells interconnected between a first stack node and a second stack node and configured to provide a first operation voltage for supplying a high voltage board net of the electric vehicle; a low voltage board net of the electric vehicle including a low voltage battery interconnected between the second stack node and a low voltage node and configured to output a second operation voltage for supplying the low voltage board net of the electric vehicle; a step-down converter interconnected between the first stack node and the second stack node and configured to output a third operation voltage to the low voltage node; and an intermediate node dividing the plurality of stacked battery cells in a first subset of battery cells and a second subset of battery cells and being connected to the low voltage node via a first switching element; and a control unit configured to detect the terminal voltage of the low voltage battery and to set the first switching element either conductive or non-conductive depending on the detected terminal voltage, wherein the control unit is configured to set the first switching element conductive if the detected terminal voltage is less than a first predetermined voltage threshold and to set the first switching element non-conductive if the detected terminal voltage is more than a second predetermined voltage threshold, wherein the low voltage battery is supplied by the second subset of battery cells via the intermediate node and the low voltage node if the first switching element is set conductive and by the step-down converter via the low voltage node if the first switching element is set non-conductive. a plurality of stacked battery cells interconnected between a first stack node and a second stack node and configured to provide a first operation voltage for supplying a high voltage board net of the electric vehicle; a low voltage board net of the electric vehicle including a low voltage battery interconnected between the second stack node and a low voltage node and configured to output a second operation voltage for supplying the low voltage board net of the electric vehicle; a step-down converter interconnected between the first stack node and the second stack node and configured to output a third operation voltage to the low voltage node; and an intermediate node dividing the plurality of stacked battery cells in a first subset of battery cells and a second subset of battery cells and being connected to the low voltage node via a first switching element; and a control unit configured to detect the terminal voltage of the low voltage battery and to set the first switching element either conductive or non-conductive depending on the detected terminal voltage, wherein the control unit is configured to set the first switching element conductive if the detected terminal voltage is less than a first predetermined voltage threshold and to set the first switching element non-conductive if the detected terminal voltage is more than a second predetermined voltage threshold, wherein the low voltage battery is supplied by the second subset of battery cells via the intermediate node and the low voltage node if the first switching element is set conductive and by the step-down converter via the low voltage node if the first switching element is set non-conductive.