The Electrics

This weekend I took care of the 12V electrics. The leisure battery had been connected to the items (water pump, light, 12V socket) directly without any fuse. The only fuse (15A) was in the line from the car battery to the leisure battery. Furthermore, the TEC3M relay had been completely incorrect wired, resulting in both batteries constantly being connected. I wanted to fix that all.

First I wanted to use one single thick wire from the car battery to the relay in the back of the car. However, I did not find a way of getting this cable through the fire wall between the engine and the passenger compartment. It appeared very difficult, and I would have to remove all kinds of paneling on the dashboard. I did not want to do this, so reluctantly I left that part of the previous cable wiring intact. I only rewired the line in the motor compartment, where for reason of supporting a higher current two parallel wires had been used. However, these were again merged into one single cable, with the same thickness. So completely pointless. Also, the cable was attached to the +12V terminal of the car battery just with a small temporary clamp. I did remove this and used a proper permanent connector, to ensure a good contact.

I did leave the remaining cabling from the car engine compartment to the rear intact, although the cable for the +12V had been black, when it should have been red.

In the rear, I removed the very heavy leisure battery from the compartment under the wardrobe and placed it in the new battery box. Connected thick cables to both terminals. There was another small issue: the external 240V input lead did have an earth connection, and that was attached to the vehicle body with a screw. I thought I would use this also as the point to connect the leisure battery mass -12V. But then I did notice that this screw was not connected at all to the vehicle metal body, but just to the plastic. Which means, it did not at all fulfill its protective role of the 240V circuit! I really would like to have a word with that person who did the wiring of all these electrics! I found a better location and grounded there the mass and the earth conductor.

Then I affixed the newly purchased 50A switchable fuse as the first item in the +12V leisure line. This will serve as the main switch to disconnect any of the electricity consumers from the batteries.

Then came a more difficult problem: cutting holes into the wardrobe wood boards for mounting switch panels. I have an electric saw, but it is very unwieldy in that very small space. So first I drilled a few holes, then I used these holes as starting points to cut further the opening, until that switch panel fit.

This panel is a series of 8 independently fused circuits, from 4A to 10A. I connected these after the main 50A fuse. Then I made the first connection by activating the available 12V socket. Works great. I chose to use for this socket the strongest fuse with 10A, to be flexible for strong external electricity consumers. Furthermore, I connected a 300W voltage converter with 240V output. Due to the potentially large currents, I connected this directly after the 50A fuse. It is not switched on by the wall panel, but by its own switch in the back.

Then I was ready to correct the wiring of the TEC3M. But then I did mistake an adjustment screw for an actual fixation screw, which I thought would be used to fix the relay onto that board. However, this was just a small potentiometer to set the voltage point when the relay should kick in. And by turning it I ruined it... and the TEC3M did now switch on always. Would be no difference to how it had been before, except that the relay now was on and could potentially empty the car battery. So I ordered another relay, this time a Durite 140A switch relay which would do the same purpose.