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
BMS 10S 36V 15A 18650 Li-Ion Battery Protection Plate Split Port/Same Port With Line And NTC Charging Protection Module
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
3IN1 Metal Streamer Cable Is Suitable for Apple Android Type C Mobile Phone One Split Three Fast Charging Luminous
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
USB C to Split Wireless Charger For Samsung Galaxy Watch 6 5 4 3 7/Galaxy Active 2 Interface Fast Charging Dock Convenient Carry
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
60W Type-C To USB C To Micro USB To Lighting Fast Charging Adapter Kit for IPhone 14 13 12 Pro OTG Converter Multi Storage 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
VR Link Cable For Meta Quest 3 VR Headset Fast Charging USB3.0 Gen2 to Type-C 5Gbps Data Transfer for Quest 3S/Quest 2/Pico4/PS5
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
Portable Multi-functional Data Cable Storage Box, 60W Fast Charging Mobile Phone Holder, Charging Cable Set, Multi Head Adapter
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
New 60W Fast Charging Mobile Phone Holder Multifunctional Portable Data Cable Storage Box Charging Cable Set for Traveling
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
TYPE-C 18650 Lithium Battery Charging Module Diy Kit DC3.7V Lithium Li Battery Charging Charger Board DIY Power Bank
Aliexpress UK