Voltage sensing split charge system with cable from Rayne Automotive 
 
Our easiest install split charge kit, with just 4 wires to connect.
Complete with clear, comprehensive fitting instructions.
Voltage sensing relay automatically allows the leisure battery to be charged only when the engine is running.
Avoid flattening your leisure battery.
 
This kit is not suitable for vehicles fitted with a smart alternator. Not sure if you have a smart alternator? Watch these two videos to find out, If you have a smart alternator, and how to test if you have a smart alternator. 
 
Additional information 
 
This kit will stop your leisure battery from draining the main vehicle battery, and allow you to charge your leisure battery from the alternator whilst the engine is running.
 
The wiring kit for the split charge is made with 16mm² cables, fuse to 100A.
 
The solid-state relay will open, allowing the current to flow between the two batteries, when the vehicle battery is charging (above 13.7V) and it will disconnect the two batteries when the voltage drops below 12.8V.
 
The VSR relay, comes with mounting screws to secure it firmly near the leisure battery.
 
Professional quality insulated joints throughout the system.  
 
Only very basic tools required to fit. 
 
The 6 way 12V fuse box, as an optional extra will take fuses of up to 10A in each fuse position.