Help with electrical glitch

[ZachO]

Hey, just got back in the trailer and things aren’t going so well. I hooked up the battery, then did some other stuff. A couple hours later I went inside and smelled something like a burning smell. The power center was clicking. I unhooked things and searched google, and read a bad battery could cause this. Had it tested and it tested “bad”. Bought a new battery. Hooked it up and things seemed fine, except it was at “fair”, according to my camper display. I was a little annoyed that the battery wasn’t well charged, but moved on. Then noticed I got no boost in power according to that display when I hooked up the solar.

Went out camping anyway, and besides that weirdness, things seemed ok. Got to camp, hooked up solar but then noticed nothing was working. Main camper fuse blown. Got a new fuse today. Power center immediately starts clicking when I hook up the battery. If I pull a fuse from the power center, when I put it back in, it sparks and blows the fuse.

Any clue what’s going on? Where do I start troubleshooting?

Thanks!

[Jack L]

Is this the original power center that Bigfoot used in 1991? If so, they have a reputation of being junk. A new one would be a good investment.

[ZachO]

Thanks.

I know, but since I rarely plug in and my solar goes straight to the battery, it’s never been a priority. Could it be the problem? I’m not using the converter, is the thing. Just the power from the battery to the fuses. I’m not plugged in.

[ZachO]

The only ground I can find was pretty rusty, so I sanded it down. Still the same issue.

[ZachO]

And just for more info, everything worked fine as of Nov 1 last fall when I winterized it.

[John in Michigan]

zacho, you say that you "pull a fuse from the power center, when I put it back in, it sparks and blows the fuse." Assuming you mean a 12 vdc fuse, that would suggest there is a short (e.g., crossed wires or shorted accessory) on the circuit that the fuse is protecting.

An example of a short created while renovating, right now I am renovating a Boler 17. Really pulling things apart. A few months ago, I had removed the rear cabinet which included a light fixture, thus leaving live positive and negative bare wires just dangling inside the adjacent cabinet. Then forgot about it. Finally last week, those two wires crossed and we were using other light fixtures on the same circuit while continuing the renovation. Poof, blew the fuse. Knew it was caused by a short somewhere. Tracked it down pretty quickly.

[John in Michigan]

Also, possibly a problem inside your power center. You said you actually don't use the converter, so I would suggest either bypassing the power center all together (use a separate DC fuse panel) or at least disconnect the DC fuse panel inside the power center from the converter.

[Dan Meyer]

What color wire is on the negative terminal of your battery? If it's black, you've probably connected the battery backward.

... don't blame me, I'm only the messenger.



--Dan Meyer

[John in Michigan]

Well reversing polarity on the battery would certainly cause problems! My power center has a 30 amp battery fuse to protect against battery reverse polarity mistakes.

[ZachO]

Wow. That might be it. I was laying in bed last night trying to figure out what could have possibly changed since last fall and that was a thought, but...

I remember this spring looking up online what was hot and what was ground and I thought I saw ground was always black. I have white on positive and black on negative.

That's embarassing...but if that's all it is, that's a simple fix.

I'll report back this afternoon. Thanks!

And yes, a new power center has been on my list since buying the camper. Just hasn't made it to priority #1, especially since it takes a little more skilled wiring than I can do myself, when it comes to AC/DC interface and all that. Straight DC I'm comfortable with.

[John in Michigan]

For travel trailers (at least the FGRVs I have owned), positive = black and negative/ground = white.

For tow vehicles, positive = red and negative = black.

[Daniel A.]

I had the convertor replaced on my 91 Zacho due to the clicking things were not charging right.


Having the terminals reversed sounds like a good possibility and easy to do.

That would pop the 30 amp main fuse.


Its also possible that mice could have gotten in over winter and chewed the wires somewhere.

[Jack L]

I have always marked my positive cables on every 12 volt system with some red electrical tape at the terminal. I can see how easy it could be to get the black and white crossed on an RV.

[ZachO]

I did the same...after thinking I read black was always negative, I went ahead and wrapped some red duct tape around the white wire I'll fix that.

I don't understand enough about my power center to know why it would be clicking. That also happens to mine when I plug in, so I figured it was a converter thing. But why would the converter be engaged when I'm not plugged in and the breakers are "off"? I don't know.

Either way, sounds like I know what my problem is for now. Funny that things did work for a few days. I had water, lights, fan...

I will get a new power center eventually.

I didn't see any evidence of mice, luckily. Had that problem last spring.

[Mike_L]

The fuse protects the circuit from overload, overheating and all the problems that go along with this situation. If the fuse blows the circuit it protects likely has a short. All you need to do is find and fix this short.
My solar panels are wired directly to the battery leads. Don't put too much faith in the color coding of these leads. The positive lead on my unit is red, the negative is black.
Your problem isn't likely your solar panels or battery unless you've reversed the polarity. The negative lead usually grounds to the frame of your unit, the positive to a power distribution box of some sort likely through a fuse. Circuits coming off the power distribution box should also be fused.
Pull all your fuses, connect your battery (check polarity) and replace the fuses one at a time starting with the fuse closest to the battery. That should identify where your problem is.
I once owned an old (English) trailer that was wired positive ground, not sure why? Not much fun to work on.

[ZachO]

Hey, thanks.

The issue was definitely reverse polarity.

So now the question is: what did I fry? The short answer is the furnace, but what part? When I try to insert the 15 amp furnace fuse at the power center, it blows. The 5 amp fuse in the furnace is fine. I don’t see any issues with the circuit board.

Short of pulling the furnace to check the wiring, what else can I check?

[Joe MacDonald]

There may be more than just the furnace on that line even though it only says furnace, carefully check. You can also disconnect the fuse at the furnace and see if the converter fuse blows
Might be better to disconnect the pos. And neg. from the furnace then try the fuse in the converter

[ZachO]

Thanks.

To be sure we’re on the same page: everything else is working. Main camper fuse is no longer blowing, all other appliances work. It’s only the furnace blowing fuses. In this case I know it’s the only thing on that circuit. I did a lot of work to it last year.

[Joe MacDonald]

disconnect the leads at the furnace in case you haven't done it already and make sure the fuse holds, to prove the wiring is still ok, if that works, then there is definitely an issue with the furnace, maybe a bad board

[The Minimalist]

I highly recommend that anyone who is unfamiliar with trailer DC systems go here:


The 12volt Side of Life (Part 1)


Good basic primer on trailer wiring, etc.