When your engine is switched off, the relay will isolate your leisure battery(s) from your main starter battery. So it does not drain your main starter battery and you will always be able to start your vehicle.
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12/24V Remote Battery Switch Relay Car Killing Switch Anti Theft Easy To Install Relay Great For Car Boats RV Microcycle And
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Built-in LED indication (lights up when VSR starts). Automatically combines two batteries when charging and isolates the two batteries when not charging,which can widely used in 12v camper van trucks, caravans, and camping applications.
eBay
Battery Switch Relay 12V Remote Control Battery DisconnectCut Off Isolator Switch Anti-Theft with Dual Remote Control Switch
Aliexpress UK
When your engine is switched off, the relay will isolate your leisure battery(s) from your main starter battery. So it does not drain your main starter battery and you will always be able to start your vehicle.
eBay
12V 200A Anti-Theft Remote Control Kill Switch For Car Boat RV Van Battery Cut Off Switch Relay Remote Battery Disconnect Switch
Aliexpress UK
Dual Battery Isolators also feature surge protection and a L.E.D indicator designed to alert the user when the unit is engaged. - Suitable for most 12V charging systems- Surge protection. When your engine is switched off, the relay will isolate your leisure battery(s) from your main starter battery.
eBay
12V Car Battery Cutoff Switch Wireless Remote Control Disconnect Battery Relay With Led Display Leakage Protection Universal
Aliexpress UK
Hot Water Heater Electric Tankless Instant 3000W Under Sink Tap Bathroom Kitchen. Parking Brake Actuator Module EPB LR072318 For Land Rover Discovery 4 2010-2016. USB Battery Welding Machine Handheld Mini Spot Welder Machine for 18650 Battery.
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Remote Battery Disconnect Switch 12V 200A Kill Switch for Car Anti Theft Battery Kill with Wireless Remote Control Relay Fobs
Aliexpress UK
Battery disconnect switch rated current: 240A. Disconnect Switches can solve the power consumption caused by such problems, and can extend the battery power and service life of cars. It can effectively protect and prolong the life of car battery.
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DaierTek Battery Switch Relay 12V Remote Control Battery Disconnect Cut Off Isolator Switch Anti-Theft with Remote ControlSwitch
Aliexpress UK
Suitable for most 12V charging systems- Surge protection. Dual Battery Isolators also feature surge protection and a L.E.D indicator designed to alert the user when the unit is engaged. When your engine is switched off, the relay will isolate your leisure battery(s) from your main starter battery.
eBay
Battery Switch Relay 12V Remote Control Battery Disconnect Cut Off Isolator Switch Anti-Theft with Dual Remote Control Switch
Aliexpress UK
When your engine is switched off, the relay will isolate your leisure battery(s) from your main starter battery. So it does not drain your main starter battery and you will always be able to start your vehicle.
eBay
Anti-Theft Car Battery Switch Relay 12V 200A Wireless Remote Control Battery Disconnect Cut Off Isolator Switch Car Accessories
Aliexpress UK