Smart Dual Battery 140A Isolator - Auto/Boat/RV, Model: VSR12, Car & Vehicle Accessories / Parts

I am using this in a Ford e350 van, converted to a camper, to maintain the truck battery under the hood and maintain 2 deep cell marine batteries in the back, which i run a fridge/micro, etc. with using a 1500 watt inverter. I was told by many old school camper guys this setup wouldn't work, but it works great! The VSR is small and lightweight, and simple to hookup and use. It has one simple LED light letting you know where it's sending voltage. Proper gauge wire is imperative, i have 6 gauge run to all batteries, with a 150 amp ANL fuse, and have had no trouble at all with this unit. I returned a much larger, heat synced Northern tool unit after i saw the difference in size. This one is great under the hood of a van or any tight space. Word of note: I did have to trim some of the plastic away where my wires run in and out of the unit. It's 2 pieces and you have to trim away part of the cover if you're using proper gauge wire to get it to sit on the base correctly. This will make sense when you see the unit in person, and it's pretty obvious the manufacturer intended for you to cut or drill depending on your application.

This is not your father's isolator. This is a smart device which senses both batteries and if either one is receiving a charge, it will enable charging of both. Most importantly if you park your tow vehicle and shut down the motor so it is no longer providing current to charge both batteries, it will isolate them and protect your starting battery. Without the isolation, devices in your boat/camper can discharge both batteries and you will be unable to start in the morning when you are ready to get the day going. I have had this happen to me. This is not just an old fashioned isolator which uses diodes and actually reduces the amount of current available to charge the batteries. That is why those older style isolators have such a large heat sink (the finned aluminum base) to dissipate the wasted energy. Notice that this isolator does not have, and does not require, a heat sink because it uses a relay that it closes or opens and has no energy loss due to internal resistance. So yes, it is a little more costly than the older "diode" isolators, but it will do a much better job protecting your batteries!

I purchased this VSR to isolate a battery in my truck camper. It is a little more expensive than a conventional battery isolator but it is smaller and easier to connect. I have tested it with my volt meter and thus far it has worked perfectly. It turns on at 13.3 volts (which protects your aux battery from being used as a starting battery by switching on only once the staring battery is fully charged). And cuts out at 12.8 volts (which keeps you from draining your starting battery when using your aux battery without the engine running). A nice feature is a little LED light that indicates when it's engaged. Also, it's rated for 140 amps, which is well over my electrical needs. There is an option to buy this same VSR with a kit, but I opted not to buy the kit because I needed higher gauge wire, and I could get it at a lower overall cost. Because of the thicker wire, I had to modify the wire inlets a little, but it was easy. I would recommend this product to anyone looking to isolate a battery.

For it being 2 simple voltage sensitive relays it is a little pricey at $75 bucks. But it works as advertised and does keep the batteries properly charged. The only issue I see is that till all batteries in the system drop to about 12.7 volts it does keep them connected. I have mine on a diesel pick-up. I will have to place a heavy diode in the wire somewhere or a switch of some type in the winter due to the truck really needing the minimum of 13.3 volts the start batteries have without this slight issue. They are 14.77 volts at rest, and 13.3 in my use, is like a 12 volt battery being at 11.5vdc. NOTE: For the KNOW IT ALLS, the batteries in MY truck are special and did not come from Walmart! Same as the Batteries you buy for Tractors, such as the 10 volt, 14 volt, and 16 volt. Use google, not your ignorance when commenting. If your lacking information, go see and learn then you too can adapt for better performance even in the world of lower informed people. http://youtu.be/G2mbNcJF8sE or search (14 Volt Battery Conversion Part 1 CE Auto Electric Supply) AND UPDATE: You can build one of these with a 100 amp SSR or a 50 to 500 amp continuous duty solenoid, and a " Range Settable Solar Charge Controller". It does the connect and disconnect cycles from the alternators output at setting you choose. Cost, $30-40

I was looking for a good quality relay to be used in my Chevy truck to isolate an auxiliary battery. My OEM relay failed, but it was 30 years old. The auxiliary battery is used as one of two batteries for my pickup camper - one is in the engine compartment and the other in the camper. I tried three different isolation relays, two of which looked pretty good. The Stinger SGP32 was the best, because its coil current was lowest. But then further searching brought me to this relay, which works with a clever design using voltage rather than just an ignition circuit. I ordered one of these and the Keyline Smart Battery Isolator, which also looked good. When I received them from amazon I found them to be almost identical in design, and upon bench testing they both worked perfectly. I ended up keeping the Keyline product and returning this one, but only because I liked the small red LED a bit better than the bright blue LED on this product. Either relay looks to be a great solution for battery isolation.

I am using this on my 2020 F150 to put an extra battery in the bed. I had heard mixed reviews on if it would work with the type of alternator I have but it worked great. I ran a fridge off my battery in the back and it charged up every time I went somewhere with the truck. Truck battery stayed full too. Im an idiot with electricity but the instructions are straight forward.

Worked great while it lasted ... about two months into operation I serviced my truck myself during which I disconnected the negative battery pole from the under the hood battery but not the auxiliary battery in my truck berd since it's not connected to anything in the truck. When I was done with work and connected the batteries back again this unit did not come on since. I wrote and email to the seller but he did not respond. As much as I like this device, it's functionality, size, and even the design (the blue light looks cool when I show people the system and the whole isolator glows blue). Maybe I just had bad luck with this unit. Anyways I cannot with good concise spend another $80 and have it fail again, so I'm trying my luck with another manufacturer. EDIT: I was wrong, and I'm sorry. While working on the truck I discovered something that a friend changed in the wiring that I was not aware of during the job mentioned above ... after fixing that issue the Smart Dual Battery Isolator came back to life and all is well. So I admit to my mistake in accusing this product of not working properly when in fact it did and it was my bad.

A bit overpriced for what it does in my opinion; however, this VSR does what it's supposed to do very well. I installed a cut off switch between my primary (starting) battery and the VSR so I can completely isolate the circuit when not needed. My application is to provide fast charging of a 100 amp-hour AGM battery that is located on my travel trailer. I ran #2 AWG wire all the way to the bumper of my truck along with the factory cables... I have a voltage drop of less than a half a volt so the battery charges like it’s sitting next to the alternator. This VSR switches on at the right voltage and has a blue light to indicate the circuit is closed. Great product except for one detail... two very small screws through two corners is all the means available for mounting the component... a wimpy way to mount a 140 Amp relay.