Dual Battery Isolator Kit 12V - 140 Amp Voltage Sensitive Relay (VSR) for Dual Battery Setup - Automatic Disconnect Switch for Car, Truck, RV, UTV, ATV, Marine
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Availability:
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Arrives
Saturday, Aug 8
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Size: 140 Iso-Pro
Features
- Advanced Dual Battery Isolator 12V Kit Designed for superior performance, this dual battery kit ensures efficient power distribution between two batteries without voltage drops. Unlike traditional battery isolator diodes, this automatic disconnect switch eliminates power loss while maintaining a seamless connection between your primary and auxiliary power sources. Compact at 2.6 x 2.6 x 2, its perfect for under-hood installations or as part of a battery relocation kit.
- Smart Voltage Sensitive Relay (VSR) for Optimal Charging Featuring a 12V dual battery wiring kit, this system automatically activates at 13.3V and disengages at 12.8V, ensuring your starting battery remains fully charged. Whether you're installing a marine dual battery kit for your boat, a dual battery kit for truck applications, or need a battery isolator 12V kit for off-grid power, this setup prevents battery drain and guarantees reliable performance.
- Built for Extreme Conditions & Rugged Durability Engineered for off-road adventures, marine use, and daily driving, this dual battery isolator kit is IP65-rated for water, dust, and vibration resistance. Its solid-state design ensures durability, making it an excellent choice for automotive, RV, UTV, and marine battery isolator needs. Whether battling tough trails or navigating open waters, count on this dual battery wiring kit to provide uninterrupted power.
- EASY-TO-USE: The 140 Amp Dual Battery Smart Isolator comes with mounting plate and hardware. Does not include installation wires. Easy-to-follow directions for the most novice DIYer. What could be easier? **If you need installation wiring, see Dual Battery Kit or ATV/UTV Kit.
- Trusted Performance with Warranty & Money-Back Guarantee Every dual battery kit by KeyLine Chargers is backed by a 12-month industry-leading warranty. If youre not 100% satisfied with your purchase, take advantage of our 30-day money-back guaranteeno questions asked! Drive with confidence knowing you have a premium battery isolator 12V kit keeping your power system running at full capacity.
Product Dimensions: 1.97 x 1.97 x 1.97 inches
Item Weight: 9.6 ounces
Manufacturer: KeyLine Chargers
Item model number: ISO-Variation
Is Discontinued By Manufacturer: No
Date First Available: April 28, 2015
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Saturday, Aug 8
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Top Amazon Reviews
Size: 140 Iso-Pro
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, since it drew the least amount of current when activated. 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 Jaycorp 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 the Jaycorp relay, but only because I liked the small red LED a bit better than the bright blue LED on the Jaycorp relay. Either relay looks to be a great solution for battery isolation. If this Keyline product proves reliable, I'll be a very happy camper! Update 8/3/21: This isolator has worked perfectly since I installed it. A 5 star product!
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Reviewed in the United States on September 4, 2019 by Ray Kawal
Size: 140 Iso-Pro
This was purchased to isolate an RV auxiliary battery used for starting the generator from the start battery bank for my engine. The original design had these two batteries banks connected together for charging purposes, but not isolated. Since the auxiliary battery was a smaller capacity battery it could drain the chassis battery during long storage periods leaving me with a dead chassis battery. Now with the battery isolator the two batteries are disconnected from one another unless the engine alternator, or other charging source, is supplying a charging voltage to the chassis battery. The battery isolator then applies the full charging voltage to the auxiliary battery, when needed, allowing it to recharge . Diode isolators have been used for this purpose and work ok, but they have a voltage drop across the diode which limits the charging that can occur. Diode isolators are solid state devices and can be susceptible to voltage spikes. This device is a much better solution. its rugged, delivers a full charging voltage to the load battery, and isolates the charging source battery when there is no charging voltage being applied. No dead battery after 6 months of winter storage.
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Reviewed in the United States on June 12, 2018 by Frank in Colorado
Size: 140 Iso-Pro
I installed this on my UTV and it works perfectly. When I have all my lights going at night and the fan kicks on it closes the isolator so I don't have such a load on the stator. I'd give it 5 stars but the ground wire wasn't attached very well and easily broke off. Easy fix, but still the solder job should of been better.
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Reviewed in the United States on May 23, 2018 by Paul Mooney
Size: 140 Iso-Pro
I originally purchased the Wirthco Battery Doctor 140A smart relay because it had the extra feature of being able to use the auxiliary battery to jump start the vehicle. Unfortunately, that unit never worked. It kept giving faults and never charged my aux battery. I called Wirthco and they claimed it was due to dissimlar batteries and would eventually fix itself. After more than six months, it never did, so I replaced it with this unit and the aux battery was charged after our first trip. The only knock I give it is that the directions are as clear as the battery doctor relay. However, given I had already ran the cables and fuses, the switch only took a couple of minutes and I was up and running. If you are not using exactly the same batteries between your starter and auxiliary, I would recommend buying this unit.
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Reviewed in the United States on March 20, 2020 by T
Size: 140 Iso-Pro
A must have item when running two batteries its been thru winter and still working great
Reviewed in the United States on April 17, 2026 by Ted
Size: 140 Iso-Pro
Problem I have is that even if the Aux-Batt terminal is connected to a battery and the Main-Batt terminal is floating it will still cut-in even at 13.25V Aux batt voltage as measured with a Fluke. So it constantly drains the aux battery until cut-off at 12.7V. I also tested the internal relay function on the Main terminal and that work identically. So the problem is that both terminals are activating the relay so the isolation never happens and the parasitic draw of the isolator itself will drain the batteries until 12.8V. Return window closed a few days ago so this is now e-waste
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Reviewed in the United States on November 11, 2025 by Mace Vindaloo
Size: 140 Iso-Pro
Worked perfectly.
Reviewed in the United States on September 28, 2025 by Janice
Size: 140 Iso-Pro
Took roughly 15 minutes to install this Isolator in our camper van and could not be more pleased. We were having issues in the rain keeping our batteries charged with solar and this is an amazing alternative when we drive to our next location. It is quiet and was the simplest electrical setup. -Came with easy to read/ fool proof directions. -Had LED light to show you if its charging -Small and compact, we installed in under our driver seat in the camper van For under $100 it is well worth the bonus battery charge and safety in those long rainy weekends. I have already had 3 of our friends get this after seeing it in our van, I highly recommend this to anyone who needs some extra juice or wants some safety in a backup to solar. If you drive your van a lot this would even work instead of a solar system. Great product!
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Reviewed in the United States on January 26, 2019 by Tori