This system is used in installations when it is not practical to have both engine alternators in parallel because of the types of regulators. It provides isolation of the port start, starboard start and house batteries independently with the ability to emergency parallel both starting batteries. A 140 amp Voltage Sensitive Relay (VSR) is connected to the port engine. When the port engine is first started the relay is open and remains open until the port start battery reaches a preset 13.4 volt. At the rated voltage, the relay closes providing charge to both the port start battery and the house battery. When the port start battery voltage drops below 12.8V (when the engine is stopped), the VSR disengages, separating the batteries, ensuring the port start battery is not discharged by house loads. The starboard start battery is always isolated to start and be charged by the starboard engine unless the emergency parallel is on.