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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3.7v Lipo Battery for Hubsan H107P 801844 3.7V 520mAh 25c Battery + USB Charger Set for H107P RC Camera Drone Accessories
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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
USB mobile power box welding-free 18650 battery charger DIY kit mobile power battery charging treasure box
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
6V 3000mAh AA Battery For RC Cars Robots Tanks Gun Boats 6v NiMH Battery Aa 2400mah 6V Battery Pack and Charger Set
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.
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1.5V AA Rechargeable Lithium-ion 4255mWh Battery With Smart Battery Charger SET 2/4 Batteries Individually Available
Aliexpress UK
(1 BB1230 Charging Unit. All of the benefits of advanced charging without any of the drawbacks. 4) Current is NOT taken from the input battery and given to the output battery. Manual mode and regenerative braking mode allows you to override this.
eBay
Estardyn XH-M601 Intelligent Charger Power Control Panel Automatic Charging Power 12V Battery Charging Control Board For Diy Kit
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(1 BB1230 Charging Unit. All of the benefits of advanced charging without any of the drawbacks. 4) Current is NOT taken from the input battery and given to the output battery. Manual mode and regenerative braking mode allows you to override this.
eBay
18650 USB Power Bank Case Kit - DIY Battery Box with Charger Module, Black for Arduino
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
10W/22.5W 3-cell 18650 battery case Detachable, solder-free mobile power bank kit Convenient DIY portable charger
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
for Makita 18650 Side Light Protection Original Battery 18V Chargers Battery Replacement Kits
Aliexpress UK