Electrical problem

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daleslad

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Aug 27, 2005
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21
I have a 2000 Nash 5th wheel and on my last outing my batteries went dead even though I was hooked up to shore power.
I've been trying to figure out what went wrong and I've got it pin pointed to a problem with something that is connected to a 7.5 amp fuse labelled accessories in the power box.
When the fuse is in it drives the converter crazy and the voltage is all over the place.
My problem is I don't know what is meant by accessories, I've called the dealer's service dept. but they weren't much help. I also called the manufacturer but the person I needed to talk to wasn't available so I'm waiting for a call back.
Bearing in mind that I don't have any batteries connected as I am in the process of looking for replacements does anyone have any idea what could be connected to the accessory circuit.
You'd think out of all of the pamphlets and instructions that they give you with the trailer that they would give you one with a schematic of the electrical system but they don't.
Thanks
 

Gary RV_Wizard

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Tough to say, daleslad. It could be most anything that doesn't have a regularly assigned circuit in the standard configuration of the wiring harness Nash uses.  The simplest expedient is to leave the fuse out and check around to see what doesn't work.  You will be able to tell pretty quickly if it is something important like the fridge or water heater controllers, 12V lighting, etc.  (not likely to be any of them anyway).

Since it is only a 7.5A fuse, I would suspect things like a stereo, VCR or maybe the TV antenna amplifier.  Or it might just be there to provide a place for dealer-added accessories. Do you have any of those?

Regardless, it sounds as though that circuit is miswired in some fashion.  Is this a new problem that just cropped up or did you just get the Nash and discover this problem?  ABout the only thing I can think of that would "drive the converter crazy" is if the converter's charging output line is sensing a high voltage feeding back, causing it to think the battery is either fully charged or shorted or perhaps reversed in polarity.  Can you be more specific about what the symptoms are?
 

John From Detroit

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Accessories is techneese for "We don't knwo what to call it so it's an Accessory", could be lights, water pump, radios, after market stuff, just about anything.  I don't know why it's driving the converter crazy however.

Try this, what does not work with that fuse pulled?

I would hook up the batteries, with that fuse pulled, and see what happens

See if they charge, (monitor them with a volt-meter)
 

daleslad

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Aug 27, 2005
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RV Roamer said:
Since it is only a 7.5A fuse, I would suspect things like a stereo, VCR or maybe the TV antenna amplifier.? Or it might just be there to provide a place for dealer-added accessories. Do you have any of those?
Regardless, it sounds as though that circuit is miswired in some fashion.? Is this a new problem that just cropped up or did you just get the Nash and discover this problem??? Can you be more specific about what the symptoms are?

Thanks RV Roamer, I will check out those items tomorrow when I get the batteries installed again.? ?I've had this trailer since it was new in 2000 and there hasn't been anything added to it for years.? I think the converter is sensing a partial short and reacting to it.? ?The voltage will jump between 8 and 9 volts when I have the 7.5 amp fuse plugged in.
 

daleslad

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Aug 27, 2005
Posts
21
John In Detroit said:
Try this, what does not work with that fuse pulled?
I would hook up the batteries, with that fuse pulled, and see what happens
See if they charge, (monitor them with a volt-meter)

Thanks John that's going to be my next step tomorrow.  I have a sneaking suspicion it might be a 12 plug in for the tv that is the only thing I can think of that I had used before my last trip.
 

Gary RV_Wizard

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I think the converter is sensing a partial short and reacting to it.  The voltage will jump between 8 and 9 volts when I have the 7.5 amp fuse plugged in.

That sounds likely.  The converter's charger circuit will have limit its output in case of a shorted battery.  You are most likely seeing the converter's regulator switching off & on, trying to charge the battery without overloading itself.  That suggests either a shorted battery or a shorted line connected to the battery. You can verify which by disconnecting ALL loads from the battery and leaving the converter/charger connected, but it appears you have already isolated the problem 12V load circuit.  Something on that circuit has shorted out and you will just have to crawl around and find it.

7.5A @12V isn't much power, so look at small loads such as LP detectors, TV amps, etc.  The 12V tv is barely possible and is just the sort of thing that might get labeled "accessory"
 

daleslad

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Aug 27, 2005
Posts
21
RV Roamer said:
7.5A @12V isn't much power, so look at small loads such as LP detectors, TV amps, etc.? The 12V tv is barely possible and is just the sort of thing that might get labeled "accessory"
Well I think I've pullled out the little hair I had and I'm not much further ahead with finding out what my problem is.  You were right about the 7.5 A fuse Roamer it feeds the radio and cigarette lighter plug ins.
I was told by the Progressive Dynamics tech. that I should be able to disconnect the battery and the converter would provide the power for the  12 volt system if I was plugged in to shore power.
I tried that but I got fluctuating voltage at the battery leads (8-9 vdc).
I found that pulling the 7.5A fuse for the radio etc. stopped the fluctuation but the 12 volt system still didn't work.
If I connect the battery again and put the fuse back in and have shore power plugged in everything seems to be working normal.
I'm tempted to ignore it and get new batteries and monitor them very carefully for a  week or two.


 

daleslad

Member
Joined
Aug 27, 2005
Posts
21
RV Roamer said:
7.5A @12V isn't much power, so look at small loads such as LP detectors, TV amps, etc.? The 12V tv is barely possible and is just the sort of thing that might get labeled "accessory"

Well as I said earlier I've located the source of the problem it was the CD Receiver.
I've been doing a little testing and stuck an ammeter in the circuit and found that with the CD Receiver connected but not turned on I am getting about 0.5 amps drain.
If I connect the CD Receiver and play a cd the current goes up to around 0.8 - 0.9 amps.
So it would seem that the unit is using more amps when it is turned off than what it takes to? play a cd.
I've contacted the manufacturer to see if they can tell me what is causing the current draw inside the unit when it is turned off but there response was and I quote "head unit's will not drain power unless the red wire is connected to constant.? It should be connected to the ignition".
I've replied? to inform them that it is in a trailer so the red wire is connected to 12volts positive and asked them to explain what is in the? unit that could be pulling that much current when it is off.
Not holding my breath on a response though.
I wonder if anyone has checked the current drainage of their trailer to see what kinds of amps they are getting for the various electric items they use.
 
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