Before starting any work disconnect the mains and battery leads.
No work is necessary in the battery box for this conversion.
Locate the cable/wires that run from the onboard charger to the battery. Usually there is a connector block near the charger. If not, cut the wires and put new connector block in so that you can connect the two together.
If you find additional wires on any existing connector block, leave them in situ but cut the wires on the battery side of this block.
Put the male connector on the charger side – female connector on the battery side so that things are the same as before you started the conversion but with a connector block now in line. The female connector is shrouded so the battery high amperage contacts are protected from accidental shorting when changing over chargers.
You will need two male and female items for this conversion. It is vital that the connectors can only be joined one way, so check this before you buy.
The absolute best way of connecting wires to the terminals is to use a good quality ratchet crimp tool and the correct crimp termination, then use heat shrink tube over the cable and the wire crimp. Using a bit of heat shrink (say 1″ to 1-1/4″ ) helps support the cable as it exits the crimp.
On the C-Tek charger, cut off the spring clamps leaving about 6 inches on the wires and fit a female connector block so that you can reconnect the spring clamps if you need to. You will have to fit a male connector on the end of the charger wires so that it plugs into the leisure battery female connector. Now you have the beauty of both worlds in so much as you can restore the configuration to the original. If you sell the caravan you will want to keep the C-Tek.
You do not have to see the C-Tek charger, so you can place it out of sight. One of the good features of the C-Tek is that when you initially set it to charge it should stay in that mode regardless of anything – even disconnecting the external power, and it is fully automatic.
As for the 230v feed to the C-Tek, I fitted a switched household socket on the floor of the caravan with Velcro and tapped into a nearby mains feed. I used a household 230v junction box and 2.5mm household cable.
There is no need to change over to the onboard charger while towing. The car alternator charges the leisure battery on a different circuit. The C-Tek is really fit and forget.
The whole job might require you to be double jointed but it is well worth the effort in knowing that your battery will be kept in optimum condition.
By Pete of the BO & Flying Tog, CT Authors