new to me class a electrical problems

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AER

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Joined
Oct 31, 2020
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22
I bought this 1998 coach a couple days and went to a campground,  trying to learn about it. It has new coach batteries. When looking at thr rv, the prior owner started the generator and the refrigerator worked.we bought it and drove to the campground,  plugged into 50amp. Over a period of a couple days, one by one everything died. The refer, water heater, both air conditioners, all lights and even the water pumps. Now nothing works.  Not on DC power, generator power or shore power. No fuses are blown in the power converter box. I am thinking maybe the power converter itself needs replacing.  But does anyone have any other thoughts while we are still traveling home?
 
First guess would be the transfer switch.  It could be either manual or automatic.  Find it and start following the power.  98 coach with 50A service? Remember things like furnace, lights, and refer all need 12VDC to work.  In the refers case it needs 12V for control circuit power.  Make sure the house battery is fully charged, then move on to the 120VAC stuff.  The converter will have 2 sections.  Section 1 will be a straight thru to the main circuit breakers.  Section 2 will take 120VAC and convert it to 12VDC which will charge the house battery and supply power for lights, etc  there should be be breakers and fuses on or close by. Easy enough to check voltages there.  Another weak point is the power cord plug itself.  After 22 years of hot plugging the plug ends could be burnt or broken.  All RV electrical is pretty simple.  A volt meter is about all you need to get started.
 
Since he had 120v power initially, I think the transfer switch is ok. And since it was gradual, odds are battery power was being used and slowly went dead. The symptoms suggest a gradual loss of 12v power - just about everything depends on 12v power for control purposes, even though it may use 120v shore power as the primary.  Even the a/c will typically stop once 12v power is lost.

When on shore power you should have 12v power provided by the converter, which also charges the batteries.  This may be not working, either because of failure or lack of 120v to it (e.g. a tripped circuit breaker).
Start by checking the 12v power right at the battery, with and without shore power connected. The battery should show 13+v if the converter/charger is working. A fully charged battery reads 12.6v or more; anything under 11.0 is considered dead.
 
Ok. We are on the road now headed home. I will check the house batteries when we get there. I am leaning towards that too now as I heard them bubbling at one point.
 
Bubbling sound, lots of misty dampness around batteries, or excessively warm batteries are all bad signs, usually meaning loss of electrolyte and overcharging.  Note that loss of electrolyte and overcharging can be either a cause or a result of some other battery problem, so don't leap to conclusions.  It's a chicken vs egg sort of thing.
 
While I agree 12V is likely the prime culpret, but I still have to wonder what else is wrong.  IF the house batyery went dead what caused it?  Shore power, or rwther lack of shore power is my first go to place.  Like I mentioned 22 years of hot plugging can create all sorts of problems.
 
Not an expert but he may not even have a transfer switch(?)

On my 1995 the shore power plug is manually inserted into the generator outlet when you want generator power.

The shore power plug is wired to the 100/115V bus and the converter/charger is hard wired to the bus with no pass through fuse.

Basically on mine the entire RV is an appliance that plugs into shore power or the generator but not both at the same time.
 
For sure it is a 12 volt issue. likely a bad converter leading to dead batteries..

So the Original Poster knows
The converter is the device that  converts 120 volts AC to 12 (Well 14.6 or 13.6) to charge and maintain the batteries (All voltages approximate for this post) 

To test hook a digital voltmeter to the batteries black to negative or most negative red to positive or most positive (See diagrams) on DC volts if not auto-ranging a range that can handle 15 volts.

NOTE the voltage and plug in. Not the new voltage and come back in 2 hours. Note this voltage and post results

You can get a meter for like 10 bucks or less at Harbor Freight.

Two battery setups

-{Bat}+T+{ery}+  These are six volt in series to make 12 volt likely GC-2 size batteries.

Hook to left and right most posts in this diagram

-{Battery}+
-{Battery}+  These are 12 volt batteries

(2nd battery optional) same Hook to left and right.

 
Ok people. I got home and took the rv to an rv service center as I was unable to resolve the problems on my own. The rv service center charged me $112.00, had the RV for 5 days and told me it was fixed and everything worked. HOWEVER when I went to pick it up, he had just simply flipped the breakers on the generator (duh! I didnt know about those) and replaced the transfer switch fuse in the engine compartment (yay!).  While showing me all the appliances worked, the refer started to work but quickly  died under all power conditions with no lights anywhere (an RM2852 Dometic Americana), plus the furnace would not turn on,  and there are 2 lights not  working. Everything else we tried, including the air conditioners, seemed to work. He told me I would have to make another appointment and bring it back for more troubleshooting which would take days. But he did confirm there was 12 volt to the refer and fuse in power converter was good. He suggested in the mean time I use a cooler and space heater,  ugh. He said the furnace and refer were on the same circuit though. TODAY I went out to the RV and started the generator, I just happened to have the power converter fuse box open and noticed a spark fly when I started the generator...... so between that and the boiling battery I experienced before, I am wondering if it could be the power converter? Though the RM2852 had some things  recalled and there is more troubleshooting to do on it according to my research..........
 
donn said:
While I agree 12V is likely the prime culpret, but I still have to wonder what else is wrong.  IF the house batyery went dead what caused it?  Shore power, or rwther lack of shore power is my first go to place.  Like I mentioned 22 years of hot plugging can create all sorts of problems.

Actually although it is 22 years old, the house appliances have not been used in about 10 years except for very little. The batteries and generator are a year old though.
 
SeilerBird said:
I always have my work done by mobile RV mechanics at my home so I can watch them and make sure the work is done properly.

I sure wish I could do that. I live in a small town 100 miles from the nearest other one though with only one rv service center and he is backed up with work at his shop :/
 
You may have a loose wire in your converter. I suggest you go in there and tighten every screw you can find ane tug gently on all wires. BUT before you do this, disconnect from  AC power and disconnect the batteries.
 
Sounds like the battery disconnect was off. All the stuff that you say went out is 12-volt control power.
 
I would not assume that the shop did any real testing of the converter. It should never throw sparks. To me, that indicates that it has a bad connection, as ChasA mentioned, or it has a serious internal problem. Did you ever measure the voltage at the battery terminals as others suggested? It's easy to do yourself. That will tell you if it's working or not.

Kev
 
A spark flying indicates one of several things

#1 is a loose or bade connections. With all power OFF look around for any evidence of the loose connection (more on this in a bit)...  You said you had the cover off the converter box. I'm going to assume this is a combination assemble with 12 volt fuses. 120 volt breakers where you can see them and the converter behind.

Now a true story that may be yours (or a variation on yours) when My RV was new sometimes the Front A/C worked, Sometimes the Rear  or both or neither and it was.... Frustrating to say the least.

Well first thing I looked at (OH. I'm a certified electronics tech, though I never really worked at it, Though not an electrician I have a bit of cross training)  I was poking around and noticed some of the black wires moved where they are clamped in the breakers....  So i broke out the #2 Square screwdriver (#2 phillips also works) and started tightening the screw.. FULL TURN,, 2 FULL TURNS  3 FULL TURNS and half a turn more... A/C worked fine after that.
The other one took a bit less but still was loose.. I then went through the entire box and tightened several screws all 3 colors.

So suspect #1 with a #2 square bit is a loose screw

WARNING work by flashlight. NO generator No Shore power 

#2 is a short but doubtful from the symptoms of "it worked at the dealer"

Document or better yet video if those screws are loose and go back to that dealer and have a few WORDS.
Ask for you what did you say that service fee is. Plus 150 for my expert advice (keep the 150)
 
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