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 13S 35A 48V Li-ion Lithium 18650 Battery Pack Charge Board Split Port Balancer PCB Short Circuit Protection
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.
eBay
21700 battery mobile power kit no welding DIY power bank Type-C battery DIY box 10W fast charge AC/DC dual charging
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
Solar Panel Kit Complete With Battery 10KW 220V 120V AC Perc Split Cell Panel Hybrid Inverter MPPT On Off Grid Home System
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.
eBay
3m 5m 7m Ready Made Split Charge Voltage Relay Kit 12V 140AMP VSR T4 T5 Camper
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
300W 600W Flexible Solar Panel 12V 24V Solar Charge Battery Kit with 60A Controller for Camping RV Home Outdoor Solar Power Bank
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
6000W4000W Solar Panel Inverter Kit – Complete Off-Grid Power System with Charge Controller & Battery Compatibility
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
CN3065 Mini Solar Lipo Charger Board Lithium Battery Charge Chip DIY Application Kit Charging Board Module
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
1-10PCS Mini Solar Lipo Charger Board CN3065 Lithium Battery Charge Chip DIY Application Kit Charging Board Module
Aliexpress UK