Dead battery, running refrigerator, etc. can put up to a 40 amp load on the battery wire to the trailer. Often they are not wired for that.

When I bought my rig, 93 1 ton with an Alpenlite (supposedly pretty good) fiver that had been rigged and towed long enough to wear out the trailer shackles, it had.

8 gauge from the battery in the trailer to the kingpin, no fuse. 14 g cable to the 7 way plug. Truck was wired with 30 amp stick fuse, 10 gauge part way, 14 gauge rubber cable part way, 12 gauge tape harness part way, multiple crimp splices.

If the fuse weren't blown, a consistent 25 to 30 amp load could have easily caused a truck fire.

Probably your tail light lenses were melted by heat from the fire reflected off the trailer.

 

I thought that too, but he said they were melting before any fire was near them.

 

I bought thru an E-bay add. I saw it, called and said I wanted to come see it.
I did.
the salesman said he would close the deal early, before I asked him to.
There was never any mention of an 'as is' deal.
but, when we left, I made a comment to my passenger the receipt said ' as is'. i was not made aware of thet and should of caught it before I signed it.
The recently new battery in it was dead. It charged in the first hour because we turned on and OFF the few lights in it at lunch. i'm possitve they were off. So was the fridge.

The brake light lenses and the trailer wire that hung down between the 5th wheel and fromt compartment--battery area-- were on fire smoke etc before the bed had any heat damage. I clearly remmeber that as I tried to unhook it, while waiting for FD .

I intend to go back to take a few more pics. it is 90 miles from my home.

Terry Frazier Rv is refusing any help and said it was an 'as is' deal.
i guess it is my loss.

Sometimes we learn the hard way.
But, I still feel they had responsibilty in this, being a dealer.
They took it in as a trade.

 

There was no fire there yet and the top of the trailer later burnt. the battery and lp compartments are still intack with only smoke damage.

 

I don't think factory trailer wiring addresses the power feed to a 7 way for a fiver, which should be a 10g 30 amp or 8g 40 amp circuit. The rubber connect wire had to be at least 10g, and needs to be inspected frequently if you're boondocking or whatever that requires heavy battery charging from the tow vehicle. The circuits should be fuse protected at both ends.

I don't know how it got that way (factory I think) but my fiver was wired with a 14 gauge connect wire and no fise. I suspect you'll find the same on yours.

The truck circuit needs to be fused for the wire size used. I have a 40 amp fuse and 6 gauge wiring in mine. (Adequate.) It came with 14 gauge (part way) and 30 amp fuse. (Fire invitation.)

It takes a prety hefty discharge to blow the top off'n an optima, so I suspect you had a fairly heavy (10g or so) wire directly to the battery with no fuse.

So here's the sequence.
1. high and steady current draw to charge fiver battery
2. 14g double rubber insulated power and ground conductors in rubber cord overheat and deteriorate. Lighting load further overloads the ground.
3. Insulation fails and cord shorts.
4. Now partially charged trailer battery feeds the short and causes wiring to heat up red hot.
5. Optima in truck feeds the short also, and causes truck wiring to heat up red hot.

dangit, I hate it when it does that.

I went at my wiring deficiencies with a vengeance, both trailer and truck I'll post the trailer project here, and the truck project on the first gen board.

 

Knowing it was a trade to their dealership, I would have to agree, at least to SOME degree. Maybe only from an ethical and moral standpoint, but still feel they should bear some of the responsibility somehow.

I will be interested in seeing some pics when and if you are able to get them. I would bet that if your insurance is going to cover this, they will be going after the dealership to recover their costs of coverage. They may not get much, or anything, but it would still be cheaper in the long run for the dealership to assist you in some way rather than be dragged thru court for months on end. Like you said tho, 'sometimes we learn the hard way'. Seems like they're going to be learning this lesson too!

j_martin has summed the situation up nicely I think. Good description of what probably took place.

 

Just noticed this. Maybe there was some kind of large draw or even short within the trailer, not related to the battery, that caused the battery to be discharged and promulgated the end result.

Even so, I think j-martins' scenario is the sequence of events that makes the most sense.

 

I will check tomorrow if the top blew off of the
Optimas.
I know my service manual shows the truck was wired with 14 gauge wires except the Ground a battery which were 12 gauge. Nothing bigger.
I'm off to a cards and rockies game. Back tomorrow.
Thanks guys.

 

Add this to what j-martins said as well:

Your truck batteries were fully charged when you hooked up to the RV, While charging the dead RV battery the truck batteries are being over-charged they in turn get hot and give off hydrogen gas. This is a common problem with a relay type connector between two batteries with different states of charge.

 

Man, sure glad you're OK- trucks and trailers come and go but life itself is a whole different story. Sorry about the loss though.

Closest thing I can relate to: Had a wheel come off a travel trailer that I had just bought from a dealer. The hub assembly and wheel were toast. Determined the lug nuts were loose- yeah, I know as the driver I had the responsibility to check them before leaving the dealership but they said they'd "gone through it and everything was good". I assumed that meant the lug nuts too. I held them to their word and they ended up splitting the cost of repairs with me. I ALWAYS check the lug nuts now....

 

If the trailer battery came with the trailer and was discharged when you left then the dealership let you leave with no breakaway protection. Something you might "explain" to them. They ARE at fault as the trailer was NOT road worthy and in a dangerous condition.

 

Great point, but the trailer MAY have had a seperate, small battery dedicated to the brake system as well as the large battery.

 

I disagree. The regulator is connected to the truck battery, and will regulate the voltage at that point. Lower voltage on the camper batteries will pull whatever current the circuit resistance will allow, but the voltage at the truck battery should never be excessive.

If they're a little low, they'll tend to pull 5-10 amps or so through a 14G circuit. No harm done, just slow charge. If they're really low, they could draw 20 amps through a 40' 14g circuit.

If the fiver is wired 8g to the pin (common) and the truck is wired pretty heavy, you could draw 30 - 40 amps through the rubber cord. Often they are just 14g wire. That'll start a fire.

Fuses would have saved the day with nothing more severe than smoked wiring.

 

The alternator senses the lowest voltage(it can not differentiate between the R,L or trailer battery) and charges accordingly, like you say the charge to the camper battery is regulated by the wire size going to the trailer ( a self resetting CB needs to be installed inline to the camper trailer) 20 amps may sound low but to a fully charged battery it is dissipated as heat / hydrogen gas.

Try installing a dead battery on one side of your truck and see what happens. Or get an older non-regulating battery charger and leave it on a battery for several days.
I have set up multiple battery systems on trucks / rv's to run various accs. The best system is to install one of these:

http://www.allbatterysalesandservice...cfm/2,655.html

However no one makes them for the computer controlled alternators in Dodge (or at least the last time I checked)

 

Right. The battery that holds the voltage down, for whatever reason, gets the current. Under no circumstances will a properly operating regulated alternator run the voltage above what a good battery would require for soak.

A bad battery can hold the voltage down to the point that the good battery in parallel with it doesn't get charged. That commonly occurs.

None of the examples you give apply to this case.