still in need of wiring help

[billhenry58]

A friend helped me rewire my camper. We got the wiring more or less run and I am trying to finish it out. The 110 side is working fine. When I was hooking up the battery a negative wire started smoking and melted back almost to the charger/converter. I traced it as the blue ground from the converter/charger. The wire goes from teh c/c to a grounding post and then continues on and picks up the ground from the heater/furnace and then continues to the negative wiring bundle to the battery.

The c/c is a PD9130, and a note on the specs states, "CAUTION RISK OF FIRE: Chassis bonding wire must be a separate wire ran directly to chassis from the grounding lug provided on the side of the converter. DO NOT connect output negative to chassis using the same wire."

Is this where we went wrong? What did we do wrong?

[Dan Meyer]

There are no standards when it comes to wiring on old campers. People have problems and will splice in any old color wire they have handy and not document their change.

Also, black is usually not negative in a trailer.

I'm betting you hooked up the battery incorrectly, possibly thru no direct fault of your own.

-- Dan Meyer

[billhenry58]

I thought that at first also, but double checked. I have 2- 6v Trojans. I hooked positive on one, negative to another, and a jumper connecting the other pos and neg posts.

We ran new wire, red to positive posts through a fuse block. Black back to negative posts on battery. Any exsitng wiring/leads were checked to see which was the hot and then we changed to red or black for the long runs to battery. I am still at a loss, but am guessing the ground is the culprit but and not sure. I would sure like to find someone to walk me thru the wiring of the 12volt, so I'll know how to do it.

[Franswa]

"I traced it as the blue ground from the converter/charger."......there's your clue right there I would guess....barring a PO substitute job....if it looks like anything original blue is never used for negative.....in RVs black is +, white is -......cars/boats are black is -, red is +........blue never enters into it

in old power centers the blue wire is a 12volt + to feed the "unfiltered" circuits (not meant for TVs, radios etc that might pick up "hum" from the converter)

at least that's what I understand (no expert, learning more every day) good luck

[billhenry58]

I'll try and post a pic tomorrow. It looks to me like it is a ground from the c/c and has an additional ground from the furnace that also goes to the battery negative post. That doesn't sound right to me BUT I am also learning as I go and still way behind the curve.

[Carol H]

Originally Posted by Franswa

.in RVs black is +, white is -

the only blue wire you will find these days on most trailers is for the electric brakes

[stevebaz]

Put a volt meter on the line it will tell you if it is 12 volt + or -. To me its probably hot output coming from the converter. Any other hot would have been fuse protected and not fried. You better map everything and verify just what it is.

[Carol H]

Normally Scamp would have two inline fuses preventing a melt down as described if battery is hooked up incorrectly. One is located right off the battery and the other just inside the trailer where the wiring harness enters.

When you rewire the trailer did you perhaps remove those?

[mszabo]

What do you mean by a jumper on the other terminals?
Should be one negitive terminal to ground, positive to negitive on other battery,
Other positive now 12 volts is your power.
Should only be white wires to ground.
Any pictures?

[Thinh]

Before connecting 2 wires' ends together, make sure it is ZERO voltage across ( measured by Voltmeter) In a trailer of combination of electrical sources, as I understand, chassis ground, negative 12volt, 120VAC ground(usually green wire), common ground or common bond of 120VAC (usually white wire), converter ground, towing vehicle ground, negative 12 volt from vehicle battery or from trailer battery itself.... are different things. You might bond one to another but if bond all together it will not work. One thing to guarantee a short circuit is...there is some voltage dropped on 2 terminals that you intend to connect. That is what happens to your case and I suspect it is full voltage drop. either 12VDC or...higher than that,..i.e...120volts AC.

[Night Sailor]

You need fuses on the positive wires. The purpose if the fuse is to protect the wire. Fuses should be as close to the battery as possible.


Sent from my iPhone using Fiberglass RV

[steve dunham]

Originally Posted by Night Sailor

You need fuses on the positive wires. The purpose if the fuse is to protect the wire. Fuses should be as close to the battery as possible.


Sent from my iPhone using Fiberglass RV

I agree with Conrad that the DC positive conductor should have an over current device (fuse) as close to the source of power (battery) as possible . Yet your system should have functioned properly without the fuse . The wire probably would not have been damaged if the system was properly fused but the source of your problem is not the lack of an over current device . IE Something is wired incorrectly!

[Night Sailor]

Originally Posted by billhenry58

A friend helped me rewire my camper. We got the wiring more or less run and I am trying to finish it out. The 110 side is working fine. When I was hooking up the battery a negative wire started smoking and melted back almost to the charger/converter. I traced it as the blue ground from the converter/charger. The wire goes from teh c/c to a grounding post and then continues on and picks up the ground from the heater/furnace and then continues to the negative wiring bundle to the battery.

I would not use one wire for all these negative connections. It can be done if sized properly but it is not a good practice. The ground wire has to be large enough support all your DC loads at once.

You should have a large gauge wire from the negative side of the battery to a negative bus (a big connector to bound all your negative leads to). Some people use the negative side of the battery. I dont recommend that. You can use the frame, but each negative needs to be securely bonded.

If you use one wire for the negative and it is not sized right, it could burn up if there is too much current going through it.

I am not sure what the blue wire is, but if that was +12V i.e. a hot lead and it was connected to directly to ground, it would get pretty hot and melt really fast. A fuse would have protected the wire from this happening.

Did you have the converter plugged into shore power when this happened? That could provide a source that would damage the wire. If the AC was off or unplugged then the battery was shorted out and it seems more likely the blue wire was at +12V as Francois mentioned.

The blue wire could have been energized from either the converter making 12V or else from the battery somehow. My bet is the blue wire was providing 12V and used for charging the battery or something and you were plugged into shore power when this happened.

When wiring you need to test one thing at a time, and use fuses to protect the wires.