No Ceiling lights on Battery Power

[aftermath]

I am stumped. I have just repurchased my old 1979 Starcraft Tent trailer. I reworked all the running, stop and tail lights. Everything works great. The two ceiling lights worked too along with and outside light I added back in the early 90's.

Today I went out and put it up to wash it. No ceiling lights, no porch light. The battery is good, 12.7V and the three lights work when connected to 110. Nothing works when just on the battery. I checked all three at the fixtures and they read 12.5 volts. I am measuring across the switch and the ground that holds the bulbs. They were working a few weeks ago and the trailer has been in my garage all the time. All grounds look good and the 12v line is fine.

If there was no voltage at the light fixture I would suspect a bad ground but I have power at all three locations but still no lights.

Help. I am stumped in Spokane.

[aftermath]

FIXED IT! Thanks Westend for pointing me toward the test light. I checked the battery and it was fine. I went to the exterior porch light and nothing.

Using the light I went next to the fuse holder mounted on the tongue and found a bad connection in the line that feeds the ceiling lights. I still have the owners manual that includes a schematic diagram. This was very helpful.

Tightened up the connection and all is good. I still can't figure out how I was getting a reading with my VOM at the light. Again, thanks Westend, you were spot on.

[aftermath]

Thanks, I will rig up a test light.

I replaced the battery-off-converter switch. It stopped working for the PO so they just wired around it. It was a mess.

I am going to have to wait for a week or more to return to the puzzle. I will let you know when I figure this out. I will figure it out, I will.

[westend]

Make sure the "battery-converter" switch is in the correct position. You may wish to jumper across that switch to see if it has failed.

Reading voltage measurements with a low voltage system can be misleading. You may have 12.5V available but not enough amperage to drive the appliance/bulb. A 12V test light is a good tool to have in this situation.

[aftermath]

Bobbo, that is what I thought but when I connect up to 120V the converter takes over and I have lights. So, the bulb isn't bad and the fixture works. I did not check the actual voltage when running on the converter. Perhaps I need to do that. I still think 12.5 VDC should be sufficient.

The only thing that was different from the last few times is that I took the trailer outside today and washed the canvas. Perhaps some water got in someplace that would cause a problem? I still am confused with the voltage reading I am getting though.

[Bobbo]

If you have a good power supply and a good ground, you either have a blown bulb or a bad light fixture.

Test the bulb in a known good fixture, and test the fixture with a known good bulb.

[aftermath]

Roy, thanks for the idea but mine is a 1979 trailer. I owned it from 1989 to 2005, no switch like this on this old gal. The owners manual warns against closing up the trailer without switching off the switch that toggles between converter and battery.

[aftermath]

Lwiddis, It is an interesting story. Bought this in 1989 and sold it in 2005. Our daughters grew up in it and it was in very good shape when we sold it. Sold it locally and it remained here in town. Youngest daughter told me she was starting to look but couldn't afford much. I went to Craigs list and wow, our old trailer was for sale. I have been working on it during the winter and it is ready to go. I am taking it out on a shake down fishing trip in a few weeks and this happened! I am pretty good at figuring things out but like I have said, this one stumped me.

If I had a bad ground I shouldn't be able to measure 12.5 volts across the light fixture. Or could I?

[RoyB]

My 2008 Starcraft 14R/T POPUP trailer has a push-button switch mounted on top of the cabinet that the fold-over sink/stove top cabinet pushes in the switch button to turn on the ceiling lights when setup. This is safety feature to disconnect the ceiling when the trailer top is down for transport. Those incandescent lamps burn so hot if turned on may cause a fire...

Perhaps the fold over sink/stove cabinet is not sitting level on the top of the bottom cabinet...

My push button switch looks like this...

Google Image

Roy Ken

[aftermath]

This trailer has a converter and not a charger. I did check the battery and it was showing 12.7 which is plenty to run two 12V lights.

I was thinking it had something to do with the ground because I just replaced the ground connection but I checked it too. Remember, I went to one of the ceiling lights and used my VOM to check the DC voltage there. I got 12.5 volts. I put one probe on the place where the light contacts the switch, I put the other probe on the ground and bingo, got 12.5. I switched the light off and repeated and got 0. Again, while plugged in the lights work so I don't think it is in the fixture. On battery only, nada.

[MNtundraRet]

Did you check the battery ground wire connection? It may be loose or corroded.

Also; did you read the battery voltage with a volt-meter before plugging into shore-power? Reading the battery after plugging into shore-power should read around 13.7 volts while charging or 13.2 volts if battery was actually fully charged.

I suspect the battery may have almost discharged.

[Lwiddis]

First time I've heard of an RVer repurchasing his/her RV and a 1979 model too boot! 38 years old!