A battery integrator combines two battery banks without the use of diodes by relying instead on a solenoid switch that connects the two banks in parallel, positive to positive, only when a charging voltage is present. When the alternator and battery charger are off, or if a large current load causes the battery voltage to drop even while charging, the battery integrator breaks the connection and isolates the batteries to prevent the higher-charged bank from dumping current into the bank with lower charge. There is no voltage drop across a battery integrator. They are typically used to allow the charging output of an inverter-charger to charge both a starting battery and a house bank while isolating them during inverter operation so that the inverter draws current only from the house bank.
