Forget the traditional diode relays and so-called solid state devices that can rob you of almost 2 amps of output power The Dual Battery Isolator is the unit designed with cutting edge programming to deliver performance - with ZERO sacrifice. This compact battery isolator was built ultra-small (2.6 inch x 2.6 inch x 2 inch) to fit almost anywhere A perfect fit under the hood to get close to your dual batteries.The Automatic 140 Amp Dual Battery Isolator is all you need to charge Two Battery Systems. Voltage Sensitive Relay cuts in at 13.3 volts and cuts out at 12.8 volts to ensure your primary battery is always charged and ready to start your vehicle. Its like having two separate power sources for each battery while only having one alternatorUnlike other isolators on the market, the Automatic 140 Amp Dual Battery Isolator is IP65 Certified. This International Protection rating means that your isolator is safe for use even for your off-road needs in dusty, wet and unexpected extreme weather environments. Great for extreme vibration applications as well.12V 140 Amp Dual Battery Smart Isolator Sensitive Relay Specially Deigned for ATV, UTV, Boats, RVsCause your accessories to run from a separate battery while the engine is not working on your vehicle, and at the mean time holding your main battery charged and your vehicle always ready to work.Product name: smart battery isolatorProduct voltage: 12VProduct features: large capacity, can switch 140 ampere current, flame-retardant shell, waterproof designCoil power: 3.4WContact capacity: 1a 140A 14VDCContact resistance: less than equal 50mInsulation resistance: greater than equal 1,00MAmbient temperature: -40~+125Service life: electrical 1*1000000 (times)size:68x68x53mmMaterial:ABScolour:BlackPackage Contents:1 * Smart Battery Isolator4 * Screw1 * terminalOnly the above package content, other products are not included.Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.