12Volt inverter inoperable???

Well, we have had our new (to us, it's a 99) fifth wheel for 2 weeks now, with the warmer weather last week it was pretty warm inside so we never needed the furnace but this last week we had it plugged in and ran the furnace while we were in there getting it stocked up and set up for our first camping trip (wanted to check everything out over the period of a week to see if everything was working properly).  Well, I went out last night to get the owners manual out to learn a little more about it but none of the lights worked.....none, not even the exterior lights (2 scare's and patio), the furnace isn't working and the range hood controls (light, fan, monitor panel etc...).  So it seems all the stuff that runs off the 12volt system are not working which indicates that the battery is dead. The 12V converter is supposed to be charging the battery while plugged into a 110 outlet but am I to assume that it is not charging?  The previous owner installed a much larger than stock battery (the battery box lid won't fit over it) so that kinda points to a possible previous electrical problem.  The slideouts, receptacles and ceiling fan all work fine. I checked all the breakers, none were tripped, checked all fuses, all looked good.  I'm going to hook a battery charger up to the battery here shortly to recharge it but was wondering what i should be testing/checking to confirm that the converter is bad.  What kind of a repair bill am i looking at?  I purchased it from a reputable dealer that we have known for a couple of years, i'm sure they will take care of us but I wanted to talk to people here in the know first.  SG

You probably have a battery disconnect switch somewhere, usually by the entry door. If it is off, nothing 12v will work.

That seems more likely than the battery going totally dead overnight. Batteries lose their charge more gradually.

Yes, the converter (not inverter) should be charging the battery and providing 12v while you are plugged in. But if the disconnect switch is off,  you still won't have power.

Oops, I can't believe I put "inverter" in the title.  I'll check out that switch.

I cannot find the switch anywhere.  The battery is on one side of the front compartment and the converter is on the other (next to the landing gear motor).  The first night I had the RV plugged in I could hear the inverter running when I opened that front storage compartment but I haven't heard it in a while.  I checked the 2 converter fuses and they are good but where should I be looking for for this switch?  Battery side? converter side?

In our MH, the switch is beside the entry door.

This is a trailer and some do not have a disconnect.  If it does, it will be inside the RV, not in the battery compartment.

It sure sounds like either a disconnect switch is open or  a major fuse has blown, taking out the entire 12v system. Few other things would have these symptoms.  Look at the battery and the cable to the positive post and see if it goes to a BIG fuse somewhere, maybe 50-100 amps. That could be blown. Also check the negative terminal wire (chassis ground). If that has no or poor connection, you get no power at all.

If you have a voltmeter, read the voltage at the battery terminals and see what it says.

Do you have an external battery charger you can hook to the battery?  Or jump it from another battery with cables? That will tell you whether it is a charge problem or a fuse/switch problem.

Time to get out the VOM and start checking things out.  Start at the house to be sure you have 120VAC, then move to the input side of the converter again for 120VAC.  Next would be the converter output side for 12VDC.  Converters do have a main fuse, plus fuses or breakers for everything on the output side.  Last would be to take the battery out and have it recharged and then load tested.

With a DVM you could check the voltage at the battery both plugged in and not. If the converter is charging you will notice increased voltage when plugged into shore power. Don't just check the cable end, check the battery post also.
  I'm unfamiliar with your 5th wheel and have to ask do your slides&ceiling fan run on 120vac?

Ok, from the battery to the loads you should have:
First a fuse or circuit breaker (Some companies put the switch first)
Then a disconnect system, this may be a switch, usually a very big switch, or it may be a solenoid, looks like a ford starter solenoid (BUT IT IS NOT THE SAME!!!!!!) This is often a latching solenoid, has 4 terminals 2 big "Bolts" and two much smaller ones. (The control terminals)

Then it goes to your fuse block

NOTE: The solenoid, if you have one, is operated by a remote switch. I have seen them just inside the door (In the step well.. where mine is) on the dash, on an overhead panel,  in fact it can be ANYWHERE there is no limit since it's a remote switch.. Operating this switch you should hear a CLUNK,  (Assumes you can hear it) I had a problem where my switch if moved to teh "STORE" position (Disconnect) Clunked well but if moved to USE.. No clunk (no 12vdc either)  I fixed it.

Switch may be labeled HOUSE/ AUX or "Use/Store"

Now... if all else fails

First charge the house battery.. An automotive "Smart Charger" is good for this

Now, make a test light... (Do this while the battery is charging) I took a license plate lamp (Auto parts store) replacement, this was a blade type socket with two leads.. Put a bulb in it, and put a clip on one lead... I put about 3 feet of wire on the other lead and a clip on the other end of that.. This is easier to use than a meter cause all you need to know is bright, dim or dark.

(Bright  good,, Dim bad connection, Dark no power)

Start at the battery.. One clip (Does not matter which) to the NEGATIVE battery terminal, one to the positive.> BRIGHT.. Good

Move the negative clip to any handy chassis metal.. Still bright,,, GOOD  Dark  Check the negative battery cable, both ends (First make sure your clip is making good contact)

Now move out following the POSITIVE cable,  if you come to any "Box" or Cylinder, touch both screws/terminals (On teh main solenoid only do the two big bolts)  When it goes from light to dark, whatever is between the light and dark terminals is the problem

On many coaches there are manual reset circuit breakers.. On my coach (A gasser) under the hood is a black box with 3 big and several small wires hooked to it  It says "Battery Control Center" on the lid

The schematic for the box shows two post-type (Push in or in this case UP, HARD, to reset) Circuit breakers extending out the bottom of the box..  My install is different, but that is a common problem point

If those breakers are tripped.  No charging (or discharging) of battery can happen.

It's very curious that your slides work and other 12v systems do not. 
Will your slides work when unplugged from 120vac? 
If they do, then your battery is good.  The problem would then have to be between the converter and the DC distribution panel
If not, then they were working off the converter which proves that the converter is good.  The problem would then have to be an open circuit (circuit breaker, switch or fuse) somewhere between the battery and the DC distribution panel.

bigskymt said:

With a DVM you could check the voltage at the battery both plugged in and not. If the converter is charging you will notice increased voltage when plugged into shore power. Don't just check the cable end, check the battery post also.
  I'm unfamiliar with your 5th wheel and have to ask do your slides&ceiling fan run on 120vac?

Click to expand...

I thought everything ran off the same system but it looks to me like the lights, furnace and stove fan run off 120 because they fire up when I plug the RV in to a 110 outlet but that's it.
Thanks for the input everybody, I'm checking stuff out as i'mtrying to get a bunch of other stuff done so I haven't been able to get very far with it.  I did place a call to Thor manufacturing and they were no help at all.

aka Porky said:

It's very curious that your slides work and other 12v systems do not. 
Will your slides work when unplugged from 120vac? 
If they do, then your battery is good.  The problem would then have to be between the converter and the DC distribution panel
If not, then they were working off the converter which proves that the converter is good.  The problem would then have to be an open circuit (circuit breaker, switch or fuse) somewhere between the battery and the DC distribution panel.

Click to expand...

O.K., I think you're on to something.  Now, when the RV is unplugged both slides will work but that's it, nothing else is working, when I plug it in the recepticles and ceiling fan work.  Now what?

HAAAAAAAAAAAA, I found it.  very weird, apparently the previous owner replaced one of the large 2 prong fuses with a mini fuse, it wasn't blown but when i grabbed it to pull it out everything fired up, it wasn't making good contact.  I feel kinda stupid but relieved.  I thought I had one of those hard to find electrical problems on my hands and was very curious to know what caused it but in my own defense that was something that might trick a lot of people at first.  Guys, thanks for the help, I went back and read through everyones posts one more time and checked the fuse panel again. Well, the good news is we found out that you guys respond unbelievably fast.

Great news.  Now go enjoy the trailer......

Glad it is fixed.

Stewie...
You should take a few minutes to read the RV Electrical Systems Primer in the library. It's a simple and short article but will help you understand what is going on and make it easier to explain when there are problems.

http://www.rvforum.net/joomla/index.php?option=com_content&view=article&id=420:v-electrical-systems-primer&catid=14:newcomers-need-to-know&Itemid=64

Meanwhile, here are a few comments on some previous statements...

(1) Re the slides: slide outs are often wired direct to the battery via their own fuse. May continue to work when other circuits do not. And vice versa.

(2) Lights furnace and stove are definitely 12v and not 120v. If you have 12v power when plugged in but not when unplugged, it means your 12v is coming only from the converter and the house batteries are either disconnected or dead.

(3) Receptacles are 120v and get their power from the shore power cable (or genset, if you have one). It sounds like your ceiling fan is 120v also, but there are 12v ceiling fans available too.

Uh Ohhh, hold the fort, now it's getting wierd.  That mini fuse that I pulled out is for something called "SO", whoever labeled it used all initials.  I thought it stood for slide out but that's not the case.  Well, I put a fullsize fuse back in it's place, everything worked fine, I returned to the RV an hour later to find that everything was shut down again so I yanked that fuse out and everything turned back on. I left the fuse out and everything was fine all night long, I left the scare light on so I could just look out the window and see everything was good, well, this morning when I left for work I found that everything was out again.  If two bare wires were touching it would blow a fuse.  I've never seen this where whatever is happening just cuts power off to the whole block. I ddn't have a whole lot of time to do anything this morning but I'd be willing to bet that when I plug that "SO" fuse back in everything will turn back on.  Should I change the block out? I can't imagine that the furnace is overloading the system all by itself but I guess thats a possibility, I just figured I would find a blown fuse if that was the case.  The fact that the previous owner had a mini fuse in that SO slot instead of a fullsize fuse is telling.  The first thing i'm going to do when I get back to the RV is shake some wires to see if one of them is touching something it shouldn't be. Any ideas?  Roamer, I haven't opened your link yet, i figured I should post this so that I could hear some responses and maybe get some ideas.........this job thing keeps getting in the way of my fun time.

is it possible that the converter is causing this issue?

adding to the ongoing saga, I shook all the smaller (14 guage) wires and nothing happened, then I shook the main feed (6 Guage red) from the Battery/relay and everything fired up.  So, I would say that there is an issue between the converter and the block, but then why did it fire back up when I pulled that small 15 amp fuse before?  Maybe I jiggled the block enough to move the red wires just enough to make better contact.....don't know.  I'm going to keep at it and see what happens, hopefully I won't have to pull a new lead.

Sounds like just a loose main power feed. Check them all and tighten as needed. Good Luck,
Jim

Forget the fuse for now and get that loose wire firmly connected. My bet is your problems will go away.