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Vsr Relay Comparison - September 2025
| 1 Best Choice  9.6Exceptional | 2 Best Value  9.5Excellent | 3  9.4Excellent |
| View DealOn Amazon | View DealOn Amazon | View DealOn Amazon |
ModelDual Battery Isolator Kit 12V - 140 Amp Voltage Sensitive Relay (VSR) for Dual Battery Setup | Model VEVOR Split Charge Relay Kit, 6mtr 12V, Automatic Dual Battery Isolator Kit with 140AMP Voltage Sense Relay VSR, Compatible with RV Marine Car Vehicle Truck Caravan Camper Yacht ATV UTV Boats Workshop | Model Nilight 12V 140 AMP Dual Battery Isolator Auto Manual Voltage Sensitive Relay with Digital Voltmeter Smart VSR Automatic Charger Disconnect w/Voltmeter for Truck RV UTV Boat Can Am |
BrandKeyLine Chargers | Brand VEVOR | Brand Nilight |
Reviews | Reviews  | Reviews |
Tech Specs | ||
product dimensions 2 x 2.6 x 2.6 inches | product dimensions 2.66 x 2.66 x 2.11 inches 3.57 Pounds | product dimensions 2 x 2 x 1 inches 11.64 ounces |
Available On  | Available On | Available On |
Our Top 3 Picks
Here are the top 3 recommended products with more information to help you find the right product for you
9.6
1KeyLine ChargersDual Battery Isolator Kit 12V - 140 Amp Voltage Sensitive Relay (VSR) for Dual Battery Setup
Why we love it
Compact size fits easily under the hood.
Ensures primary battery is always charged.
Durable and weather-resistant for off-road use.
Main highlights- Trusted Performance with Warranty & Money-Back Guarantee – Every dual battery kit by KeyLine Chargers is backed by a 12-month industry-leading warranty. If you’re not 100% satisfied with your purchase, take advantage of our 30-day money-back guarantee—no questions asked! Drive with confidence knowing you have a premium battery isolator 12V kit keeping your power system running at full capacity.
- 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.
- Complete Dual Battery Wiring Kit for Easy DIY Installation – No complicated setup required! This battery isolator kit includes (1) 140 Amp voltage sensitive relay, (1) 20-ft red power cable, (1) 2-ft black ground cable, (2) positive marine-type brass battery terminals, (1) negative brass terminal, tinned copper lugs, heat shrink tubing, cable ties, and step-by-step instructions. Perfect for DIYers of all skill levels—just connect the power wire in, power wire out, and you’re ready to go!
- 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.
- 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”, it’s perfect for under-hood installations or as part of a battery relocation kit.
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9.5
2VEVOR26% Off
VEVOR Split Charge Relay Kit, 6mtr 12V, Automatic Dual Battery Isolator Kit with 140AMP Voltage Sense Relay VSR, Compatible with RV Marine Car Vehicle Truck Caravan Camper Yacht ATV UTV Boats Workshop
Main highlights- Superb IP65 Waterproof: Voltage sensitive relay is waterproof up to IP65, which means that your isolator is secure for use even in dusty, wet, and unexpected extreme weather environments. Great for extreme vibration applications as well.
- Rugged & Durable: Split charge relay is made of a premium plastic material, which is shockproof and dustproof, ensuring maximum strength and durability for long-lasting usage. You will always be prepared and confident to take on any challenge.
- Fit Various Vehicles: This isolator kit 12v has a compact size of 2.66" x 2.11" x 2.66", suitable for almost anywhere. Mainly used in off-road vehicles, camper vans, RVs, caravans, 4x4s, leisure vehicles, ships, yachts, marine applications, etc.
- Easy to Install: This split charge relay kit comes with complete accessories, allowing you to start installing directly without purchasing additional components. Besides, we have detailed instructions for you to complete the installation easily and flawlessly.
- Dual Battery Isolator: The smart battery isolator 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. It can charge two batteries simultaneously and isolate them from each other when the vehicle is turned off.
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9.4
3Nilight
Nilight 12V 140 AMP Dual Battery Isolator Auto Manual Voltage Sensitive Relay with Digital Voltmeter Smart VSR Automatic Charger Disconnect w/Voltmeter for Truck RV UTV Boat Can Am
Why we love it
Charges two batteries simultaneously.
Durable in extreme conditions.
Real-time voltage monitoring.
Main highlights- Wide Application: Like Having Two Separate Power Sources, The Dual Battery Isolator Kit Enables Your Accessories to Run From a Separate Battery While the engine is not running on your vehicle While keeping your Main Battery Charged and Your Vehicle Always Ready to Go and Start When You Want It. Suitable for 12v camper van trucks, caravans, RV, ATV, UTV, Boat and camping applications.
- Safe and efficient: The dual battery isolator is made of high-quality material casing and a silicone seal, withstanding extreme weather conditions and vibrations. Its IP66 waterproof rating ensures safe off-road use in dusty, wet, and unpredictable environments, providing you with a reliable and durable solution for your marine or automotive dual battery needs.
- Real-time voltage display: The Dual Battery Isolator 12V 140 AMP is equipped with an LED display that shows the current voltage status in real-time so that you can check the battery status at any time. Important Note: This item is not compatible with Lithium Batteries
- Package Includes: 140amp smart battery isolator with voltage display; Mounting Hardware(screws, nuts, spring washers, ring terminal).
- Function: The Voltage Sensitive Relay (VSR) ensures that the primary battery is always charged and ready to start the vehicle by cutting in at 13.3 volts and cutting out at 12.8 volts. When your engine is turned on and the starting battery is fully charged, the isolation will start charging the second (auxiliary) battery at the same time. Enables you to charge two batteries from one alternator at the same time.
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Value for money
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