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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FEATURES: Made of high quality material, strong fiberglass, reinforced nylon shell. Built-in LED indication (lights up when VSR starts). Surface or panel mounting options provide flexibility in installation. Suitable for 12V 4WD, marine, truck, caravan and camping applications. Package includes： 1 x 3 Meter Split Relay Kits.
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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
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
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
The dual battery insulator can automatically combine two batteries when charging and isolate them when no charging takes place to ensure efficient power use. When your engine is switched off, the relay will isolate your leisure battery(s) from your main starter battery.
eBay
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
The dual battery insulator can automatically combine two batteries when charging and isolate them when no charging takes place to ensure efficient power use. When your engine is switched off, the relay will isolate your leisure battery(s) from your main starter battery.
eBay