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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Box Battery Lifepo4 12V 60Ah/80Ah/90Ah/105Ah Battery Storage Box Solar Cell RV Yacht Battery Plastic
Aliexpress UK
Ideal for housing larger batteries like a 100Ah 200Ah. 440mm – Length across lid at widest point. 240mm Width of lid at widest point. Designed to protect/insulate the base of your leisure battery. 270mm Height (including lid).
eBay
8PC PKCELL AA Battery 2200mah AA Rechargeable Battery 1.2v NI-MH Batteries and 2PC Battery Box for
Aliexpress UK
Will fit most leisure batteries up to 110amp. Includes divider and 2 x fixing brackets. Perfect for securing or storing your leisure battery. Supplied with strap to keep the lid secure.
eBay
12v 24V Lifepo4 Battery Box 12v 24V 50ah 90ah 100ah 200ah 280ah Solar Cells Case RV Lifepo4 Battery
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. When your engine is switched off, the relay will isolate your leisure battery(s) from your main starter battery.
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Renogy 300Ah 12V LiFePO4 Battery, Mini Size Lithium Iron Phosphate Leisure Battery with 5000+ Deep
Aliexpress UK
The Polypropylene plastic is acid resistant and provides durable protection to the battery. The output sockets allow easy connection to a whole range of camping facilities such as portable fridges and LED TVs, as well as allowing convenient charging of phones and tablets.
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2pcs/set 12V Battery Plastic Case Storage Box For Milwaukee 48-11-2411 M12 Li-ion Battery Box
Aliexpress UK
Plastic lightweight leisure battery box with lid. Perfect for securing or storing your leisure battery. Supplied with strap to keep the lid secure.
eBay
Lifepo4 Battery Case Box 12V 50Ah 80Ah 90Ah 105Ah 120Ah 150Ah 180Ah 200Ah Battery Storage Boxes
Aliexpress UK
Designed to protect/insulate the base of your leisure battery. Black Plastic Full Battery Box. Note: Suitable for maximum battery size: 35 18 20cm. 1 x battery Box. Ideal for housing larger batteries like a 100Ah 200Ah.
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12V 24V Lifepo4 Battery Case 50Ah 90Ah 105Ah 120Ah 150Ah 200Ah Battery Storage Boxes Yachts RV
Aliexpress UK
Designed to protect/insulate the base of your leisure battery. Black Plastic Full Battery Box. Dual USB Ports 12V/24V LED Interior Reading Light Caravan Boat Touch Switch New. 2x 12V USB Spot Touch Dimmable Lamp LED Reading Light for Campervan Caravan Boat.
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LiFePO4 Battery Box 12V Lithium Screwdriver Battery Case Housing Removable For 70Ah RV Caravan Solar
Aliexpress UK