An automatic 140 Amp dual battery isolator is all you need to charge the two batteries of the systems. The voltage-sensitive relay houses at 13.3v and with cutouts at 12.8v to ensure that the first battery is always charged and ready to start the vehicle. It's like having two separate power sources for each battery with only one alternator! Unlike other isolators on the market, the 140 Amp automatic dual battery is ip67 certified. This international rating means that your isolator is safe to use even for off-road needs in dusty, wet, and unexpected extreme weather conditions. Also great for extreme vibration applications. This battery isolator is suitable for 12V 140 Amp, Truck, SUV, RV, ATV, UTV, Boat and so on. Forget about traditional diode relays and so-called "solid-state" devices that can rob you of almost 2 amps of power output! The dual battery isolator is a device designed with edge cutting programming to provide performance-with ZERO sacrifice. This compact battery isolator is built very small to fit almost anywhere! Perfect fit under the hood to get closer to dual batteries. Make accessories to start from a separate battery when the engine is not running in your vehicle, and in the meantime keeping your main battery charged and your vehicle always go