Finding and connecting to an ignition live?

“What is, and how do I find an ignition live?” This is perhaps one of the biggest areas of uncertainty for our customers. This blog post will help you locate an ignition live on your vehicle, taking the stress out of connecting up your split charge system. 

Please note; this is relevant to CTEK battery to battery chargers and ignition triggered split charge systems only. Not Orion smart chargers or voltage sensing split charge relays.


We will start with the ‘what is an ignition live’ to make the how to easier.  An ignition live is any wire, that is only 12V+ or live when the ignition is on. Once the ignition is turned off, this must be 0V. Signal voltages aren't suitable. so for this reason we would suggest trying something like the power to your 12V socket (cigarette lighter) or the radio, something like that. 

How to;

  •       Begin by turning your voltmeter to DC Volts, 20. This will allow you to accurately read at 12V. connect the common lead (usually black) to a good known earth point.
  •       Locate your wires, this can be at the back of the fuse board (there will be lots here) or the cigarette lighter, light switch, radio etc. Basically anything that you know only works with the key on is a great place to start.
  •       Remove the plug from your chosen component and insert the red probe on your meter into each wire.
  •       Once you have found a wire that is 12V with the ignition on and 0V with the ignition off, this is the wire to use.
  •       Connect the red wire on your split charge system to the proven ignition live.


For help with fitting the rest of the split charge system, please refer to the downloadable instructions under your product in our shop.

Please note; all connections need to be checked by a qualified auto electrician before any power is switched on.