2010 HR 42 SKQ Electrical Short In Rear Run Box

[bigkelly]

We returned home yesterday evening to an odor of hot electrical wiring. Our coach was plugged into our homes 50 amp outlet including a surge protector. When I opened the entrance door the first thing I noticed was the steps failed to deploy. The frig was off as well. There is a run box located in the right rear compartment behind to the batteries compartment, When I opened the access door there was the odor. Inside to the left it had shorted out somehow, Melted wires. I'm assuming fuse holders etc. From the looks of things the damage is localized to the rear of the box. all other components are blackened apparently from the smoke and heat. I took photos but, I don't know how if I can post them for viewing. I'm certain I can repair/ replace the damaged components. What concerns me is what caused the failure? The coach convertor was still active,. Nothing on the incoming ac circuit had tripped. Honestly I feel very lucky we didn't lose the entire coach. Have any of you all experienced this issue? Any direction or cause will be greatly appreciated.

  

[desertdeals69]

What is the year and model of your coach?  The melted wires are 12 volt?

[bigkelly]

2010 holiday rambler endeavor. Model 42 SKQ. The chassis batteries were isolated (off). The interior 12 volt light were still working. But the step and the refrigerator would not. I bypassed the ac to frig went to home ac power. and it still would not turn on. Honestly I'm lost at this point.

[wolfe10]

Yes, not quite sure what is bad:

Are you talking about the ATS (Automatic Transfer Switch). So the 120 VAC in from shore power and generator-- single out to main 120VAC breaker box?

Or  12 VDC, and if so what is it?

 

[bigkelly]

The manual I have refers to it as a rear run box. It houses big Boy battery isolator. Also what they refer to as a Bird module Bi-directional isolator relay delay. Is there a way to send any photos? I've taken a few shots of the boxes components. Thanks.

[bigkelly]

Here are some pics.

[bigkelly]

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[bigkelly]

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[bigkelly]

Here is 1 more

[dickandlois]

4 hours ago, bigkelly said:

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Big Kelly- In this picture - it pictures a damaged 20 amp fuse and a large quantity of solder that was melted!! This is not normal !

Can you compare this picture to the drawings that you posted? This is part of the Big Boy  Isolator Relay. Something shorted out to do the damage and requires some service help to get it repaired. The whole lower right section of the fuse board is damaged !!!!!!

Rich

[kaypsmith]

The Big Boy is a battery isolator, is designed to allow charging of both house and chassis batteries, then while the coach is not running or being charged by the inverter/converter, separates the house and chassis batteries to keep your house battery drain from discharging the chassis battery. It is no more than an overgrown solenoid. It looks like that the activation circuit has fried. Could have been caused by a shorted/bad battery, or shorted alternator. This looks like a major problem, and will require someone that is qualified to make the repair, as the source of the meltdown needs to ne identified and corrected before any repairs are attempted to the circuit boards and wiring. Hope that you have some type of warranty, if not, be sure to contact your coach insurer, some vehicle policies will cover this type of damage.

[bigkelly]

 Rich,

The lower left enlarged circled drawing is the component that shorted out. The arrow drawn is indicating its location if viewed from access door opening.

Kaypsmith.

I have the same concern pertaining to what caused the short. I located the component thru REV group. WOW $1,200.00  It is being shipped. When I spoke to REV technical support the best answer was, it could've been moisture or something just failed. The bottom line they had nothing to offer. I'm  mechanically inclined. Journeyman heavy mining equipment for many many years. I can accept a electrical component failing. But the what if, is running in the back of my mind. The area we reside has 0 shops or repair facilities. I've not looked into any other damage. The front relay/ fuse compartment is okay. I will test batteries, alternator, and attempt to inspect as many connections, and trace wiring sources. Thank you all for your feed back. If I locate the actual cause, which may end up simply being a circuit breakdown I will post my finding.

Kelly

  

[wildebill308]

Kelly, I hope for that price you are getting the whole assembly. 

Bill

[kaypsmith]

Be sure to check the alternator for a possible short as well, I had one to fry a battery once because of a bad regulator, it was the old Chevy style with a built in regulator, sure hope that you don't have any other problems.

[bigkelly]

Bill,

1 power control card with mini fuses, relay, basically it is only the part of the run box that failed. I will post a picture later today.

[jleamont]

Looks like high resistance to me. Either the starter is drawing excessive amperage or those connections were loose/corroded prior. From the paper schematic above in the middle of all of that is a lug that feeds the starter motor. How many Chassis batteries are on the starter circuit?

[bigkelly]

2 chassis batteries. Here is a pic of what $1,200 buys you.

[abyrd]

Looking at the damaged board I would speculate that a component failed that caused a direct fault between a positive conductor to ground.  You get the damaged that occurred required a significant of current to generate the heat to cause the damage.

 

Looking at your new board at looks the larger red jumpers are in close proximity to a black jumper.  If the red conductor is a positive lead and black negative there may have been a short between these jumpers caused damage.

I would definitely check all wiring external connection for grounds before making any connection to the new board.  As a precautionary measure I would make a test jumper with a 20- 30 amp inline fuse and temporally connect in series with any external positive lead, once it check OK remove series jumper and make permanent connection.

Jim

 

 

 

[dickandlois]

Big Kelly, Call and ask for the PDF Files for all the DC wiring on your 2010 HR 42 SKQ. Real interesting owning an RV / coach and no service centers in the area. 

Sure glade to know more about your background and the equipment you serviced. It helps others also know that if we use electrical terms - you will know them or when to ask for more information.

As others have mentioned it took one H of a current to do the kind of damage your picture shows and the one item that makes me jittery is - them mentioned a component failing ? One would think that any part that could fail and draw that kind of current would have its OWN fuse !!

All the items mentioned by the others are valid items to check. I'm kind of leaning towards something coming loose and causing a path for  the high current short or a large high current cable that was rubbing on something and shorted to ground.

Take pictures of all and every connection you remove and test the larger cables for rubbing or loose connections-they will be welded in place, if there connection point was loose in most cases. All the fuses pictured and labeled in the information you forwarded to the forum are to small for the components they supply power to to cause things to melt.

Primary 12 volt power cables, positive and negative, starter circuits(but I see a 30 amp fuse for that circuit) and it should fuse a starter start relay. Any starter cables run between the damage and the starter?

The corner / edge that is basically gone - so something drew a high current - under, in the area or a primary dc supply wire used something under the board to complete the circuit.  

Rich.  

NOTE! there are 2 - What look like fuses that are commonly used to protect the inverters from high current loads located just above the damaged area - Is the one just above the damaged area still reading good?

[bigkelly]

Rich,

All the fuses are okay. I'll check and clean all the battery terminations. There is a possibility the pc card failed. I've seen it happen many times over the years One particular front end loader I used to work on had 7 controller boxes loaded with them. It was a Letourneau diesel/ electric drive machine. It utilized a diesel prime mover direct coupled to an ac generator. The ac was converted to dc thru the solid state conversion system. The pc cards can fail for numerous reasons. heat, dust, moisture, vibration, voltage spikes. etc.. Not sure what took mime out. I assure you I will determine the root cause of the failure.  You mentioned my background. 27 years with my current employer. 10 of those was as journeyman heavy equipment mechanic. And the past 17 years managing a mining operation. I have repaired any heavy mining equipment we 've used. Cummins electronic control certified, Detroit Diesel Electronic control certified, Industrial fluid power hydraulics certified, Payhauler hauler certified. built many Cummins, Detroit engines. Build Harleys Davidsons for fun. I've worked and repaired just about anything on wheels or tracks over the years. 2 unique machine we operate and maintain at my location are Marion 7400B electric draglines. They are 1948 year models and run everyday. They sure don't build machine like that anymore.  Thanks for the reply back.

 

Kelly