MOTOR VEHICLE HAVING TWO VEHICLE ELECTRICAL SYSTEMS WITH DIFFERENT VEHICLE-ELECTRICAL-SYSTEM VOLTAGES

Motor vehicle is provided with a first onboard power supply with a first voltage source which provides a first onboard power supply voltage and with a second onboard power supply with a second voltage source which provides a second onboard power supply voltage different from the first onboard power supply voltage, wherein the two onboard power supply voltages are direct-current voltages, wherein at least one power supply isolating device connects a connection point of the first onboard power supply and a connection point of the second onboard power supply, wherein the power supply isolating device includes at least one semiconductor device, wherein the power supply isolating device has a reverse direction and a forward direction, and wherein the forward direction of the power supply isolating device is directed from the first onboard power supply into the second onboard power supply.