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
36V Li-ion Battery Charger 3A Output 42V3A Charger for 36V Lithium Battery High Quality Fast 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
12V/30A DC To DC Charger With Bluetooth Automatic Smart Battery Charger Car Battery Charger For GEL
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
54.6V 10A / 48V 10A Battery Charger for 48V Li-ion Battery for 13S Lithium Batteries Fast Charge
Aliexpress UK
Allows split charging of second battery bank without discharging the primary/start battery, relay makes at 13.7 volts and breaks at 12.8 volt. If Input volatge exceeds 13.3V, the circuit will be connected automatically, and the RED indicator will be ON.
eBay
Adjustable charger 12V 100A lithium charger 14.6V 100A lifepo4 charger 0-15v 0-100A battery charger
Aliexpress UK
CBE 12v Split Charger for Engine & Leisure Batteries. * Keeps both your leisure and engine battery charged from your Solar panels etc* * Keeping your batteries fully charged for maximum lifespan * * Charges engine battery only when Leisure battery reaches near full capacity, whilst keeping them independant of each other * * Leisure battery is constantly connected to the solar charger, engine battery receives solar charging that would otherwise have been wasted energy!* * Ideal for Caravans, Campers, House and leisure boats* * Very easy installation, two fixings and three wires. Black to Chassis of vehicle (Earth) plus one wire to Leisure battery + and one to Engine battery plus!*
eBay
Lifepo4 Charger 12V 60A 100A Lithium Battery Charger 110V-240V Input 0-15V Adjustable Quick Fast
Aliexpress UK
Automatically combines two batteries when charging and isolates the two batteries when not charging,which can widely used in 12v camper van trucks, caravans, and camping applications. When your engine is switched off, the relay will isolate your leisure battery(s) from your main starter battery.
eBay
12V 60A Lifepo4 Charger 100A Lithium Battery Charger 100V-240V Quick Charging Fast Adapter for
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
XTAR DRAGON VP4L PLUS 18650 Battery Charger Capacity Tester Checker Fast Charge Batteries Pack AAA
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
12v Lifepo4 Battery Charger 50A/60A power bank Voltage Current AdjustablFast Charge Lithium Battery
Aliexpress UK