Vehicle electrical system, particularly for a truck

An electrical system of a motor vehicle, comprising:

• a first battery and a second battery;
• a starter generator, which operates at least in a starter mode and a generator mode;
• and
• a switch arrangement that, in the starter mode, connects said first and said second battery in series, to power said starter generator with a high voltage, and that, in the generator mode, recharges at least said first battery from said starter generator;
• wherein said switch arrangement comprises semiconductor switches that control switchover of said second battery between the starter mode and the generator mode, wherein said semiconductor switches comprise current-limiting semiconductor switches.

Vehicle electrical system, comprising:

• a first low-voltage vehicle electrical system energy storage device;
• low-voltage vehicle electrical system consumers supplied with voltage by said first energy storage device;
• a starter generator, which, in starter operation, is supplied with voltage from said first energy storage device and, in generator operation, re-supplies said first energy storage device with voltage;
• an additional low-voltage energy storage device, which, in starter operation of said starter generator, is connected in series with said first energy storage device for a higher voltage for the starter generator and, in generator operation of said starter generator, is connected in parallel with said first energy storage device for a lower voltage;
• an inverter having an intermediate circuit capacitor;
• and
• a protective resistor;
• wherein said protective resistor is periodically connected between said inverter and said additional energy storage device prior to a series-to-parallel or parallel-to-series switchover of said additional energy storage device.

An electrical system of a motor vehicle, comprising:

• a first battery and a second battery;
• a starter generator, which operates at least in a starter mode and a generator mode;
• and
• a switch arrangement that, in the starter mode, connects said first and said second battery in series, to power said starter generator with a high voltage, and that, in the generator mode, recharges at least said first battery from said starter generator;
• an inverter provided between said batteries and said starter generator;
• a protective resistor;
• and
• at least one further switch that connects said protective resistor between at least one of said first batteries and said inverter when said switch arrangement switches the system between the series connection of said batteries and the parallel connection of said batteries.