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 OR Solar Panels Module solar cell power 120W 240W for 12V/24V Battery charger Photovoltaic Panel Wholesale
Aliexpress UK
Adaptive 3-phase Charging : Bulk, Boost, and Float. 1 x 500mm RED 70amp READY MADE cable Relay to fuse holder lead. 2 x 250mm RED 70amp READY MADE cable from Battery to fuse holder lead. 2 x MTA MIDI Fuse holders.
eBay
21V Cordless Power Drill,Handheld Screwdriver Drill Set with 25+1 Torque Setting,1.5AH Li-ion Battery&Fast Charger
Aliexpress UK
2 x 250mm RED 70amp READY MADE cable from Battery to fuse holder lead. 1 x 500mm RED 70amp READY MADE cable Relay to fuse holder lead. 2 x MTA MIDI Fuse holders. Red&Black Heat shrink to protect all the connections.
eBay
18650 Lithium Li-ion 3.7V 4.2V Battery Charger Board DC-DC Step Up Boost Module TP4056 DIY Kit Parts
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
500W1000W Solar Panel Kit 12V Solar Panel 100A Controller USB Port Portable Solar Battery Charger for Outdoor Camping Mobile RV
Aliexpress UK
(1 BB1260 Charging Unit. All of the benefits of advanced charging without any of the drawbacks. 4) Current is NOT taken from the input battery and given to the output battery. Manual mode and regenerative braking mode allows you to override this.
eBay
6V 5000mAh NiMH AA Battery and Charger set For Rc toys Cars Tanks Robots Gun toys parts For Rc Boat 6V Rechargeable Battery
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
Toocki Mini Data Cord Wire Set Watch Wireless Charger USB C To Tpye C Fast Charging Cable Travel Multi Function Organiser Box
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
DEWALT DCD7781 20V Cordless Hammer Drill Compact Brushless Electric Screwdriver Driver Compact Kit Exclude Battery and Charger
Aliexpress UK
Built-in LED indication (lights up when VSR starts). 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
5.5V Mini Small Solar Panel Module Kit Multifunctional Solar Battery Charger Silicon for DIY Toy Board
Aliexpress UK