When your engine is switched off, the relay will isolate your leisure battery(s) from your main starter battery. So it does not drain your main starter battery and you will always be able to start your vehicle.
5m Leisure Battery Split Charge Relay Kit 12V 140A VSR For Camper Caravan
Starter Battery Charger to Leisure Battery Split Charge Relay Kit for Camper Van
Starter Battery Charger to Leisure Battery Split Charge Relay Kit for Van Camper
VSR 12V 140A Sense Camper Van Leisure Battery Split Charge Relay Kit 3M
5M Split Charge Relay Kit 12V 140A VSR For Caravan Leisure Battery W/Fuse Box
12V 75AH SFL 75AHC100 Leisure Battery ULTRA Leisure maintenance free
