Forget the diode relays and so-called "solid state" devices that can you of 2 amps of output power The Dual Battery Isolator is the unit designed with programming to deliver performance - with sacrifice. This compact battery isolator built ultra-small (2.6 inch x 2.6 inch x 2 inch) to fit anywhere A under the hood to to your dual batteries.The Automatic 140 Amp Dual Battery Isolator is all you need to charge Two Battery . Voltage Sensitive Relay cuts in at 13.3 volts and cuts out at 12.8 volts to your primary battery is always and to your vehicle. It's like having two separate power sources for each battery while only having one alternator Unlike other isolators on the market, the Automatic 140 Amp Dual 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 .12V 140 Amp Dual 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 and your vehicle always to work.Product name: smart battery isolatorProduct voltage: 12VProduct features: capacity, can switch 140 current, -retardant shell, waterproof designCoil power: 3.4WContact capacity: 1a 140A 14VDCContact resistance: less than 50mInsulation resistance: 1,00M temperature: -40~+125Service life: electrical 1*1000000 ()size:68x68x53mmMaterial:ABScolour:BlackPackage Contents:1 * Smart Battery Isolator4 * Screw1 * terminalOnly the above package content, other are not included.Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.