Multi-voltage battery device for a motor vehicle, comprising: - a first electrical output terminal and an electrical earth terminal for the provision of a first rated voltage; - a second electrical output terminal and the electrical earth terminal for the provision of a second rated voltage; - a first series circuit of a first battery cell group and a first controllable switch between the first electrical output terminal and the electrical earth terminal, wherein the first switch is electrically connected into the first series circuit via two terminals (SA1, SA2); - a second battery cell group, that is electrically connected between the second electrical output terminal and the first electrical output terminal, and is connected switchably in series with the first battery cell group; - a battery management assembly for operating the multi-voltage battery device, wherein the multi-voltage battery device also has: - a protective resistor that is electrically connected between the two terminals (SA1, SA2) of the first switch, and thus parallel to the first switch; - wherein the first switch is configured to bridge the protective resistor when in a closed switch state; - wherein the battery management assembly is configured to switch the first switch into an open switch state to protect the first battery cell group in the event of an excessively high current or of an electrical short circuit between the first electrical output terminal and the electrical earth terminal; - a second switch that is electrically connected between the two terminals (SA1, SA2) of the first switch, and in series with the protective resistor; - wherein the battery management assembly is further configured to switch the second switch into a closed switch state in the event of the excessively high current or of the electrical short circuit between the first electrical output terminal and the electrical earth terminal; - wherein the battery management assembly is further configured to switch the first switch into the open switch state and to switch the second switch into the closed switch state in the event that the motor vehicle is in an idle mode, that is to say is not in the driving mode or in another active mode. - a first electrical output terminal and an electrical earth terminal for the provision of a first rated voltage; - a second electrical output terminal and the electrical earth terminal for the provision of a second rated voltage; - a first series circuit of a first battery cell group and a first controllable switch between the first electrical output terminal and the electrical earth terminal, wherein the first switch is electrically connected into the first series circuit via two terminals (SA1, SA2); - a second battery cell group, that is electrically connected between the second electrical output terminal and the first electrical output terminal, and is connected switchably in series with the first battery cell group; - a battery management assembly for operating the multi-voltage battery device, - a protective resistor that is electrically connected between the two terminals (SA1, SA2) of the first switch, and thus parallel to the first switch; - wherein the first switch is configured to bridge the protective resistor when in a closed switch state; - wherein the battery management assembly is configured to switch the first switch into an open switch state to protect the first battery cell group in the event of an excessively high current or of an electrical short circuit between the first electrical output terminal and the electrical earth terminal; - a second switch that is electrically connected between the two terminals (SA1, SA2) of the first switch, and in series with the protective resistor; - wherein the battery management assembly is further configured to switch the second switch into a closed switch state in the event of the excessively high current or of the electrical short circuit between the first electrical output terminal and the electrical earth terminal; - wherein the battery management assembly is further configured to switch the first switch into the open switch state and to switch the second switch into the closed switch state in the event that the motor vehicle is in an idle mode, that is to say is not in the driving mode or in another active mode.