--- product_id: 257387252 title: "Dual Battery Isolator Kit 12V 140Amp Voltage Sensitive Relay VSR Double Battery Automatic Charger & Wiring Cable Kit" brand: "mayspare" price: "$162.08" currency: USD in_stock: true category: "May Spare" url: https://www.desertcart.us/products/257387252-dual-battery-isolator-kit-12v-140amp-voltage-sensitive-relay-vsr store_origin: US region: United States of America --- # 140A Capacity 12V Power Complete Kit Dual Battery Isolator Kit 12V 140Amp Voltage Sensitive Relay VSR Double Battery Automatic Charger & Wiring Cable Kit **Brand:** mayspare **Price:** $162.08 **Availability:** ✅ In Stock ## Summary > 🔧 Power Up Your Adventures! ## Quick Answers - **What is this?** Dual Battery Isolator Kit 12V 140Amp Voltage Sensitive Relay VSR Double Battery Automatic Charger & Wiring Cable Kit by mayspare - **How much does it cost?** $162.08 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.us](https://www.desertcart.us/products/257387252-dual-battery-isolator-kit-12v-140amp-voltage-sensitive-relay-vsr) ## Best For - mayspare enthusiasts ## Why This Product - Trusted mayspare brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **⚡ Smart Voltage Control:** Automatically cuts in and out to protect your primary battery. - • **🛡️ Lifetime Warranty:** Enjoy peace of mind with our 100% quality guarantee. - • **🔋 Dual Power Management:** Effortlessly manage two batteries for uninterrupted power. - • **🚗 Universal Compatibility:** Perfect for ATVs, UTVs, boats, RVs, and more! - • **🔌 All-Inclusive Installation:** Comes with everything you need for a hassle-free setup. ## Overview The MaySpare Dual Battery Isolator Kit is a robust 12V, 140A system designed to keep your primary battery charged while allowing accessories to run from a secondary battery. With a smart voltage-sensitive relay that cuts in at 13.3V and out at 12.8V, this kit ensures your vehicle is always ready to go. It’s compatible with a wide range of vehicles, including ATVs, UTVs, boats, and RVs, and comes with a lifetime warranty for added assurance. ## Description Working Condition:When the engine is started, starting and auxiliary batteries are separated allowing only the starting battery to be charged. When the charge voltage reaches 13.3 volts the Voltage Sensitive Relay engages allowing both starting and auxiliary batteries to be charged. This is indicated by the red light in the top LH corner being illuminated.When the engine is stopped and the battery voltage falls below 12.8 volts the VSR disengages separating the start and auxiliary batteries, at this point the indicator light will be out and the auxiliary battery continues to power any accessories without risk of draining the starting battery.Product Features：?? No voltage drops comparing to battery isolator diodes (0.6V).?? Robust Glass Fiber reinforced Nylon enclosure.?? Surface or panel mount options provides flexibility when installing.?? Optional Storage Mode allows zero power consumption when the engine is of.Product Specifications：Nominal Voltage | DC 12VCombine Voltage | DC 13.3VOpen Voltage | DC 12.8VContinuous Rating | DC 125A Intermittent Rating | DC 140APower Consumption | 10mA (Standby)/ 330mA(Engage) / 0mA (Storage)Terminal Studs | M6(1/4”)Package Includes:1 x VSR (Voltage Sensitive Relay) with mounting screws1 x 6-meter red cable terminated at both ends1 x 600mm black earth cable2 x Positive marine battery terminals1 x Negative marine battery terminal ## Features - 12V, 140A, 13.3V cut-in voltage, 12.8V cut-out voltage,; Package Include All the Bits and Pieces Needed for a Complete Installation - Working Voltage: Having Voltage Sensitive Chip,Rely Cuts in at 13.3 Volts and Cuts out at 12.8 Volts to Ensuring Primary Battery is Always Ready for Vehicle to Run. - Fuction: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. - Compatibility: This battery isolators are small and suitable for almost anywhere, for ATV, UTV, Boats, RV's，marine vehicle, truck, caravan - LIFETIME WARRANTY :100% High Quality and Enjoy Full Life Warranty, Free Exchange ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B081JL6ZXP | | Brand Name | MaySpare | | Coil Voltage | 12 Volts | | Connector Type | Screw | | Contact Current Rating | 140 Amps | | Contact Material | Silver | | Contact Type | Normally Open | | Current Rating | 140 Amps | | Customer Reviews | 4.4 4.4 out of 5 stars (355) | | Manufacturer | MaySpare | | Minimum Switching Voltage | 13.3 Volts | | Mounting Type | Panel Mount, Surface Mount | | Number of Items | 1 | | Number of Terminals | 3 | | Operation Mode | Automatic | | Part Number | US-Battery kit | | UPC | 742089521075 | ## Product Details - **Connector type:** Screw - **Contact material:** Silver - **Contact type:** Normally Open - **Current rating:** 140 Amps - **Mounting type:** Panel Mount, Surface Mount ## Images ![Dual Battery Isolator Kit 12V 140Amp Voltage Sensitive Relay VSR Double Battery Automatic Charger & Wiring Cable Kit - Image 1](https://m.media-amazon.com/images/I/71hE4P1kgzL.jpg) ## Questions & Answers **Q: what type of power runs continuously from the start battery to auxiliary to charge it through the cable???** A: When the isolator reads the need to charge the second battery it will be charged with the alternator of the vehicle **Q: Does this item have an internal fuse? Do I only need to fuse my auxiliary battery?** A: No it does not. I highly recommend installing a re-settable 150A fuse between your main battery and the isolator. **Q: are the cables copper clad aluminum or all copper?** A: Copper **Q: Can I use this to connect 2 RV batteries in parallel with differet amperage so that the leisure battery only kicks in when the primary battery low?** A: So they are connected in parallel when charging. The batteries can be of different amperages. However if the non stater battery drops below 12.8 volts it will disconnect from the system so your starter battery does not discharge. Starter and non-starter battery connections are labeled. The yellow wire coming out of the controller can be connected to a switch with the other side connected to ground. If you move the switch so yellow wire goes to ground it will bypass the disconnect and connect both batteries in parallel regardless of the voltage of either battery. Hope this helps. ## Frequently Bought Together - MaySpare Dual Battery Isolator Kit 12V 140Amp Voltage Sensitive Relay VSR Double Battery Automatic Charger & Wiring Cable Kit - MICTUNING LED Digital Double Voltmeter, Round Panel Voltage Monitor Blue for Car Pickup RV Truck Dual Battery Pack - TKDMR 10pcs 1/0 AWG-3/8 Battery Lugs,Heavy Duty Wire Lugs,Ring Terminals,Battery Cable Ends,0 Guage terminals,Battery Terminal Connectors with 10pcs 3:1 Heat Shrink Tubing --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.us/products/257387252-dual-battery-isolator-kit-12v-140amp-voltage-sensitive-relay-vsr](https://www.desertcart.us/products/257387252-dual-battery-isolator-kit-12v-140amp-voltage-sensitive-relay-vsr) --- *Product available on Desertcart United States of America* *Store origin: US* *Last updated: 2026-11-12*