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 20Ah Battery 18650 Lithium Rechargeable Battery Built-in Bms for Silverfish 250W-750W Bafang Motor Kit with 42v 2A Charger.
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
8000mAh 24V Rechargeable Lithium Battery for Makita Power Tool Replacement Electric Tools Lithium Ion Battery with US/EU 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
2800mAh Rechargeable 3.7V Li-ion 16340 Batteries CR123A Battery for LED Flashlight Travel Wall Charger 16340 CR123A 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.
eBay
DC-DC 12V lithium battery lead-acid battery charger 9-36V to 12.6V13.8V14.5V low-voltage battery charging power converter DCMWX
Aliexpress UK
This is undoubtedly an effective solution for the efficient charging of lithium iron phosphate batteries.
eBay
4x 3500mAh for bosch 14.4v battery BAT038 Battery /Charger BAT040, BAT140, GSR 14.4 V, 35614,BAT041 Battery Power Tool
Aliexpress UK
Battery Chemistries: Wet, Gel, MF, CA, EFB, AGM & LIB. Safety Class: CLASS II. 1 x UK plug. 1 x Battery Clamp Connectors. All rights for the final explanation reserved by Carpartsource.
eBay
12V 20Ah New Original Battery Pack 18650 Rechargeable Battery With BMS Charger 3S5P For Fishing Bicycle Large Capacity Batteries
Aliexpress UK
Battery maintainer perfect for charging agm,gel,wet,vrla, sla, deep cycle, mf,efb batteries, lead-acid batteries. Output: 12V. 1 x UK plug. 1 x Battery Clamp Connectors.
eBay
7.4V 2500mAH 2S 10C Lipo Battery Balance Charger for 7.4v Battery for RC Hobby Dropship Wholesale Lithium Battery MN82 MN128
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
10S3P 36V 100000mAh 36V lithium battery pack 18650 lithium battery suitable for Xiaomi M365 electric scooter battery+42V charger
Aliexpress UK