Electrical system for a vehicle with start/stop

A method of operation of a motor vehicle, the vehicle having an internal combustion engine operable in a start/stop mode enabling shutoff of the internal combustion engine while electrical systems of the vehicle are running, and an electrical system including a primary battery selectively connectible to a starter motor for the internal combustion engine via a starter solenoid;

• a secondary battery, an alternator, and additional vehicle electrical loads arranged in parallel with one another and selectively connectible in parallel with the primary battery via a charge switch;
• and, in parallel with the secondary battery, a DC/DC converter and associated bypass switch in series with a third electrical energy source, the method of operation comprising:
• when the engine is stopped during a start/stop event:
• the charge switch is open, the bypass switch is open, and the DC/DC converter is boosting;
• and
• during a warm-start of the engine after a start/stop event:
• the starter solenoid is closed to supply power to the starter motor, the charge switch is open, the bypass switch is open, and the DC/DC converter is off.