Unusual (?) problem with 12volt power on 2005 18FBR

bettyford · 10-06-2011, 08:41 AM

I know these sorts of things can be hard to diagnose over the internet, but there seem to be some unusual circumstances here that may help pinpoint a more specific cause to my problem

I've been having intermittent problems with the 12-volt power not working, but the problem would usually just "go away" and things would then operate fine off the battery. Now, the problem seems to be here to stay. I have already checked the following:

battery is confirmed to be fully charged (just bought it in june)

i believe there is no battery disconnect switch on the 2005 18fbr

i checked the 30 amp fuse coming off the battery and it is fine

battery terminals are cleaned and connected properly

inspected wiring under camper for obvious splices or wears and didn't see anything

here's the weird stuff:

the last time we camped, the battery would not work at all but after we returned from our 2.5 hr drive home, we opened the camper to find the battery WAS working!

when i leave the camper plugged in to house power for at least 30 minutes and then unplug it, the battery will actually work for a little while, and the meter by the sink even says it is fully charged. but the minute i turn off a light that was on, or change the voltage draw in any way, the power is killed and i get no 12 volt power.

i don't see the little "spark" i used to see when attaching the positive terminal

thanks for any help... confusing issue since the problem used to be intermittent. is it possible that the battery is not working at all, but by hooking the house power up I am able to build a latent charge in the system that will then power things briefly?

**LJAZ** · 10-06-2011, 10:42 AM

My best guess (and it's just a guess) is that you have a bad ground somewhere. It started out loose which would explain the intermittent issue - making contact sometimes and no contact at other times killing the power.

When you walk over to turn off a light you might be just 'wiggling' the loose ground connection enough to break contact and disconnect the power.

This would be consistent with not getting any spark when you connect the positive terminal because with the bad ground you have an open circuit.

Since you already have checked the battery and confirmed its good and fully charged. I would start by tracing the negative cable from the battery and insuring that it's connection point is clean and tight.

bettyford · 10-06-2011, 04:06 PM

thanks LJAZ! I will inspect the ground (really both) wires coming off the battery as they wind along under the camper. i know this has to be something simple!

i did hook up my voltage meter to the camper when plugged in to the house power, and there is NO power going to the battery either. would that still conform to the loose ground idea or could it be something else?

**LJAZ** · 10-06-2011, 04:56 PM

Yes. If the ground to the battery is not making a good contact the battery won't charge since you have an open circuit.

It's a good idea to check the positive cable connections as well since a loose connection there will also cause problems.

There are probably some other things that could be causing your problem, but it's better to check the simple stuff first.

bettyford · 10-09-2011, 07:59 PM

Okay, some more troubleshooting (and weirdness) went down this weekend after our trip to myrtle beach...

During the trip, the camper was plugged in to 30 amp power. I took the opportunity to visually inspect the wiring from the battery along the under-carraige of the camper. I could not find any fray or splice in either the positive or negative connection, and the fuse at the battery was still good. After checking out of our site, we tried running some lights off the battery and it was a no go. after a few minutes, enough charge seems to come through to make the clock on the radio come on and the propane alarm whine, which could only be stopped by turning on a light (which zapped all remaining power)

from what i can tell by this, SOME sort of a charge is getting through the battery...

when we returned home from our trip, we were puzzled (but not surprised) to find the battery working perfectly! So, then I'm back to thinking that we must be hitting a bump and whatever was shorting out made contact again. Without moving or even entering the camper, i decided to disconnect the battery from the camper to test its voltage. it was at 12.7. When i re-connected the battery back into the camper, it wouldn't work at all! So, i plugged the house power in for a few minutes and then unplugged it again. The battery then worked the lights and radio in the camper just fine. UGH!

The last thing I did was test the battery again with it hooked into the camper. It read at 12.7 volts. I then plugged the camper into the house power while the voltage meter was still connected to the battery, and it went immediately up to 12.9.

I've decided to leave it plugged in over night to see if the battery will fully charge. Sorry for the long description, but I wanted to provide as much info as possible... thanks again for taking the time to respond.

bettyford · 10-09-2011, 08:34 PM

well, the battery WAS working when i typed that last post. i went back out there about an hour later and decided to unplug the house power from the camper just for the heck of it, to make sure the battery was still working. NOTHING! Again, the camper had not moved, jiggled, or been walked in. I plugged it back in and decided to give up on messing with it any further...

**LJAZ** · 10-10-2011, 12:23 PM

Sounds like you've eliminated all of the easy stuff. The only things left that I can think of is that there is either a bad connection at the panel or there's a problem with the panel itself.

This is just my best 'guess'. I've never torn into one of these and I'm not entirely sure of how all of the wiring goes. I've looked online to find a 'typical' wiring diagram for a travel trailer, but have never found anything that is detailed enough to be useful.

Hopefully someone with more knowledge than I will chime in.

rosner · 10-14-2011, 11:47 AM

We had almost the exact same problem with our a couple of weeks ago after we took a weekend trip to a local state park. When we got to the park and tried to plug in we had no power so we hit the reset a couple of times and we finally got it on. About midnight the second night our lights would start flashing on and off and then would completely turn off. i went out and unplugged from the post and plugged back in but nothing. So we sat for a few hours with no power and then all of a sudden on the came. But unfortunatley a couple more hours and they started flashing again and then went off. The next morning we headed home after a cold night with no power thinking the problem was with the post at the park. Got home plugged in and the same thing happened. Found a blown 30 amp fuse and replaced and thought we had the problem licked. A few days later went out to get something out of the camper and the same thing happened with the flickering lights. So we checked the battery and it was completely dead. Took it to local auto parts store to see if it was bad and they tested it and said it was good. Final option was to take it in to local rv service store and come to find out the converter was bad. The camper is only three years old so never thought it would be that.
We read your story and it kinda sounded the same. Please let us know when you figure out what the issue was. Hope its an easy fix

JRC · 10-18-2011, 06:09 PM

We had the same type symptoms. It was a bad power converter.
Changed it out myself. Had to buy the whole electric panel/power converter unit.

bettyford · 12-26-2012, 11:29 PM

well, it turned out to be a short in the wiring that leads from the battery to the fuse, and into the camper itself! Strangely, it was quite hard to find because SOME charge was making it through. the problem was in the section where the leads from the battery were spliced into the main lead.