Please see below a basic guide to all of our split charge systems with help and advise to hopefully help you choose the right kit, first time.
The reason to install a split charge system
The main reason to install a split charge Relay kit in your vehicle, is to charge a second or leisure battery while you are driving. This means you will have enough power or charge in your second battery to use it when you are stopped, camped or working, to use whenever you need it. It will isolate the second battery from the main or starter battery of your vehicle when you are stopped. This will then ensure the main battery doesnt get drained of power when you are stopped, so you will always have enough power in your main battery to start your vehicle. So basicly whenever the vehicle is started the relay will allow power from your vehicles charging circuit usually known as the alternator or generator to charge the second battery or batteries.
A split charge relay explained
A Split charge relay is simply just a heavy duty switch which is controlled by either the vehicles ignition system, a simple on off switch or the more modern voltage sensitive relays which are the Simplest to install, has a small electric circuit in the relay which detects the rise in voltage when the vehicle is started. It doesnt matter which type you use as they all do the same job. When they are switched on they allow power to pass through the relay to charge the second or leisure battery and when they are switched off they isolate the main battery from the second battery so like I explained above will always ensure you have enough power to start the vehicle. We offer three very simple to install Split Charge Systems
Intelligent (VSR) Voltage sense Relay Kits
The voltage sensed relay kit we supply is the simplest to install. There is no need to supply a switch or ignition feed to control the relay as they work on the rise and fall of the voltage from the alternator when the vehicle is running. The relay cuts in to allow power to charge the axillary battery at approx. 13.3 volts and cuts out to isolate the axillary battery at approx. 12.8 volts. All you have to do is fix all the split charge kit components into you vehicle and connect them all together from your starter battery to your second/leisure battery.
Heavy Duty relay ignition controlled Systems
The ignition or switch controlled split charge kits are a bit more complicated to install but not too difficult. The relay is simply controlled by a 12v feed which can be taken from the alternator warning light wire, any positive ignition feed when the vehicles ignition is on or even just a simple on/off switch but if using the switch method its important to remember to switch it off when you stop to ensure the batteries are isolated so the starter battery isnt drained.
Modern Brake Regenerative Braking Battery to Battery Charging Systems
On modern vehicles now fitted with braking regenerative smart charging systems it is recommended to only use a modern battery to battery charger. We stock and sell the Sterling power products that have been specially designed for this use and come with full fitting instuctions on how to set up the chargers for these vehicles. Please see a PDF file to explain more about why you can onle use this type of charging system for your vehicle
Please see the list of split charge systems we supply plus pdf links to there fitting instructions
Light Duty Split Charge Systems
All of our lower priced Light Duty kits are all supplied with 42amp cable.
This type of kit will be supplied with a heavy duty 100amp ignition switched relay.
We supply this range of split charge systems from 1-7mtrs with or without leisure battery terminals
for light duty split charging for general camping and leisure use.
"Please click hear for our ignition controlled relay fitting instructions".
Or for a 70amp (VSR) voltage sensitive intelligent relay.
"Please click hear for our voltage sensitive relay fitting instructions".
All our light duty kits can be supplied from 2mtrs to 8mtrs and are a great way to charge up to a 110ah leisure battery on a budget
This type of split charge relay kit are ok for all Day Vans, Camper Vans, Mobile Workshops, Boats and cars using light domestic 12volt auxiliary power for, Lighting, Fridges, and most general camping and leisure products.
Medium Duty Professional Split Charge Systems
All of our Medium duty Split charge kits are all top quality professional kits supplied with 70amp(10mm2)cable. These kits can be supplied with either a heavy duty 100amp switched relay or 140amp (VSR) voltage sense intelligent relay and can be supplied from 2mtrs to 10mtrs. We also offer this range of kits with ready made leads for simpler installations saving you time and money. This type of kit is great for charging 85amp to 110amp leisure battery(s) and like our (leisure) kits are great in all Day Vans, Camper Vans, Mobile Workshops, Boats and Cars. This type of kit can allow you to charge your leisure battery(s) at a much higher rate safely, so can be used on all systems using low power amps and inverters
Heavy Duty Professional Split Charge Systems
All of our professional are the same as our heavy duty Split charge kits but are all supplied with 110amp(16mm2)cable. These kits can also be supplied with either a heavy duty 100amp switched relay or 140amp (VSR) voltage sense intelligent relay and can also be supplied from 2mtrs to 8mtrs. We also offer this kit with ready made leads for very simple installations on the (VSR) system. This type of kit is great for charging 85amp to 220amp leisure battery(s) and like our (leisure & Heavy Duty) kits are great in all Day Vans, Camper Vans, Mobile Workshops, Boats and Cars. This type of kit can allow you to charge your leisure battery(s) at a much higher rate safely, so can be used on all systems using higher drain electrical items, like amps, inverters, winches and high power motors in professional vehicles.
Industrial Split Charge Systems
We also offer a Very Heavy Duty Kit Supplied with 110amp (16mm2) or 170amp (25mm2) Cable. These kits are all supplied with a very heavy duty 180amp (VSR) voltage sense relay and can be supplied from 2 mtrs to 8 mtrs. This type of kit is suitable for charging systems with multiple banks of batteries or to use with very high power winches and motors so are great to use in all mobile workshops, industrial vehicles and 4x4s.
All of the above Split charge kits or parts we supply are all top quality, UK supplied and fully tested E approved parts.
Simply 12 Volt are part of Simply Split Charge Ltd a small family run business offering one of the largest range of split charge kits and systems we think you will find anywhere. We know and understand that one kit does not fit all. If you cant find the type of kit or system you need or require any help or advise on which kit will be best for you then please contact us at
For a human then please call our sales office
Monday to Friday 9am to 5pm or Saturday 9am to 1pm