iFutniew Dual Battery Smart Isolator 12V 140A Voltage Sensitive Split Charge Relay VSR Car Accessories Relay VSR for Campers

[Function]--With the engine running the VSR will engage when the starting battery reaches 13.3 Volts and the LED light will illuminate. This means that both batteries are now linked and the system is working.Once you turn off your vehicle the system will disengage the two batteries as it reaches 12.8 Volts, leaving your main battery safe to start again [Working Voltage]--Voltage Sensitive Relay (VSR) cuts in at 13.3 volts and cuts out at 12.8 volts to your primary battery is always and ready to run your vehicle About this item: [Wide Compatibility]--This battery isolators are small and suitable for almost anywhere, for ATV, UTV, Boats, RV's, marine vehicle, truck, caravan [Important Note]--When connecting accessories to your second battery they are fused within 0.98FT