Battery Isolator - H/D Truck

For vehicles with two batteries, battery isolators prevent charge imbalance, stopping the higher-charged battery from draining into the lower one while enabling simultaneous charging. The amp rating matches the alternator’s max output. 4-stud isolators are required for Delcotron-type alternators, while 3-stud models are incompatible. Littelfuse Cole Hersee isolators have a per leg rating of half the alternator rating (e.g., 75A alternator = 37.5A per leg).