Discovery Rain water has take out my 12 Volt lighting

valiant81

New Member
Aug 25, 2020
4
8
3
tasmania
Hi folks; Ok i have had a 2012 Jayco discovery pop top since new, well looked after and beside a couple of teething issues with the cupboard door latches, our caravan has been well loved.
Over the last 12 months i have had a problem with the 12 Volt lighting in the roof of the caravan, at its worst you would turn on one of four light in the caravan and it would come on not at full brightness but dim. Turn on a second light and the other light would also come on but would also be dim and both lights would be dimmer than having only one light on !!

I have had a bit of water get in to the roof space/cavity. This was attended to and no more water damage, but i do have a bit of paint peeling from were the water has soaked through.

OK time for a bit of checking out with my meter and see if i could track down the loss of voltage and the issue with the lights.
OK, Battery fully charged and the battery was only 12 months old (12 Volt 220 Ah ). Check the voltage at the junction box for the feed for the roof lights and no problems at the junction box. All of the roof lights are of high brightness led lights. Far brighter than the old globe of yesterday !!

Next was to check the voltage at the light fittings, with one light on there was just on 10 Volts. The distance from the first light to the junction bos was around 2 mtrs. Turn on a second light and the voltage would drop down to around 8 Volts !! even worse when a 3rd light was turned on !!

On removing the first light i found only 1 set of wires for the supply to that light and another set for the of wires for the second light, there were none, i only had one set of wires ( one wire for the positive supply from the junction box and a second wire for the negative wire. These are normally in a fig 8 cable ).

Only thing for it and checking the other lights they were all the same, only one fig 8 cable to each light, this ment there was a junction box in the roof, somewhere !!. But where !!!. I did contact Jayco at there head office in Dandenong and they could not help and were also not interested as my caravan was now around 8 years old and way out of warranty..

Coming from a electronic background i new what was required and that was a rewire and the lights in new cable to each light!!
OK with some new heavy duty low voltage cable, i tried to use the old cable as a pull through in the roof cavity. No such luck !! the roof cavity is filled with a composite insulation and this makes it impossible to run this cable this way and keep it concealed.

The only way to run new cable was to run the cable in conduit, junction boxes and install on to the top of the roof. Being a pop top this also had it's problem with the roof flexing under my weight. It took a couple of hours to complete the work that was required. Plenty of silastic was used under the junction boxes and at points were water could enter. It may look a bit of a eye sore, but how else was i going to run the cables
The final result was that now all of the lights now work and not a hint of voltage drop.
It has now been 18 months since we have had this problem and now it is all fixed, one would think that water could not take out a 12 Volt circuit, but it did !!! Thank god there is no 240 Volts for lighting in the roof !!