Forget the traditional diode relays and so-called "solid state" devices that can you of almost 2 amps of output The 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 under the hood to get close to your batteries.The Automatic 140 Amp 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 your primary battery is always charged and to start your vehicle. It's like having two separate sources for each battery while only having one alternator Unlike other isolators on the market, the Automatic 140 Amp Battery Isolator is IP65 Certified. This 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 Battery Smart Isolator Sensitive Relay Specially Deigned for ATV, UTV, Boats, RV'sCause 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 to work.Product name: smart battery isolatorProduct voltage: 12VProduct features: capacity, can switch 140 ampere current, flame-retardant shell, waterproof designCoil : 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 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.