Smart Battery Isolators Littelfuse Smart Battery Isolators are more flexible than traditional isolators and work with all alternator types. Littelfuse Smart Battery Isolators are smaller, lighter, and generate less heat than similar products. The series features no diode efficiency losses and reduces the charging system workload by not connecting the auxiliary battery until the primary battery is charged to 13.2V. The resulting lower strain on expensive charging components extends their useful life. These battery isolators allow bi-directional charging from an alternator or from shore/campground power charger/converters when available.