"Let there be LIGHT...and there was no light !!!!

[Randy Wilson]

Tidings from Morristown IN.

I'm a rookie trying to check out my newly acquired '75 31ft. rear bath Land Yacht. OK, a few days ago I plugged in the outside cord to 120V. Well I didn't have any lights inside. I heard this humming sound near the bath. So I assumed it was the Univolt system talked about in my owners manual. Now the dc battery in the dude had been in there for 10 years of storage. So I charged up a fairly new Wally World car battery that I had around here with a 10 amp charger. I installed this into the battery compartment and BINGO. I had interior light, radio etc. Now getting to the point finally, huff puff, I had left the cord plugged into my 120V. Today when I went into the trailer to try to get my Fridge going. NO LIGHTS....NADA.

I am thinking bummer, get a flashlight you boob and get to checking. I went to the rear and could hear the univolt unit humming. Next I opened the fuse box inside the bathroom closet and checked the fuses. It seems all fuses were OK (visually checking) I checked the outlet in the kitchen and I had 118v. reading on my Fluke meter. I went out opened the battery compartment and it appears that my dc battery was dead. I pulled out my battery and put it back on the 10amp battery charger to build it back up. Now for the sake of this discussion at the battery terminal clamps proper at the battery compartment....with the outside 120v. plugged in and hearing and knowing that the univolt system is humming if I put a meter on the terminal clamps proper should I get a reading? In other words how do I check to see if my univolt system is recharging my dc battery as needed?

Please respond. Randy Wilson (apprentice in waiting)

ps my unit does NOT have that optional whiz bang by golly Onan generator battery charging system, as talked about in my owners manual.

[3Ms75Argosy]

Just because it is humming, don't assume it's working. Your univolt should be putting 14 volts or so at the battery terminals. If it's not, verify that your fuses to the battery are whole (not blown). A good replacement is the intelipower converter.

You can still check if your fridge works, as the 12v and 120 volt system are independent (the fridge should work off of propane and 120volts).

However, your battery should not be dead overnight without a load on it. You may have a open circut somewhere (or maybe the battery did not get a full charge either?)
Marc

[overlander63]

There are two 50 amp fuses, one for +, and one for -, usually located outside the housing for the Univolt.The negative one, for some reason, tends to corrode, and even though it looks good, will not conduct electricity. Try removing each fuse, one at a time, and make sure they all have continuity with your Fluke meter. Then reinstall them, and see if you have around 13.5 volts DC at the battery. If so, it was just a bad connection, and life is good.
If not, I had to take apart our Univolt and repair a connection inside the unit. It was humming, like yours, and doing not much else. After repair, it functioned properly for the rest of the time we owned the trailer, and as far as I know, it still is.

[john hd]

also,

check the fuse holders and fuses inside the door of your univolt.

check on each side of each fuse with your fluke, if you have an open fuse you will find it that way. there should be 12 volts on each side.

if you find a fuse that is not open but not passing current try spraying the entire assembly, fuses and all with wd 40. then rotate each fuse a half turn. you may discover some of the fuse holders have lost their "spring". you can gently close them back up with a needle nose pliers to get a little more life out of them.

do as terry suggests and check the two large fuses outside the univolt, and yes, he is correct there is one for positive and negative.

good luck and please report back....


john

[john hd]

In other words how do I check to see if my univolt system is recharging my dc battery as needed?

also also,

the lights in the trailer should get brighter when you plug it into 120 volts regardless of battery condition.

you should see a rise in battery voltage when you do this from 12.something to approx 13.4 volts.

john

[Randy Wilson]

Tidings, I took a serious shot at trouble shooting my problem of having no lights. As directed by folk from the forum I went to my Low Voltage Distribution Panel in the bottom of Bathroom closet (curb side). The illustration is located on the left side of page 75 in my 1975 owners manual. I checked all those 50 amp fuses. I took all those heavy wires (one at a time) lose from their lug proper. It seems that the ends of the stranded wire was corroaded (sp)., on most of these. Hence I cut the ends of the wire and stripped the insulation back to expose clean shiny copper. Now after it was all said and done working with a flashlight an all I think this was a dumb move. Reason I think perhaps those ends now may have been "tinned" as such with silver solder or something to help them have better conductivity. Oh well too late now. I know I have clean tight connection all about this panel. After doing all this re-terminating and checking the fuses I went and pluged in my outside 120ac volt source. As before the Univolt was humming away. I went to the exterior battery compartment and took my Fluke meter and checked the battery terminals coming from the univolt to see if they were putting out any voltage. ZILCH....NO JUICE AT-TAL. So now I know I have good fuses. Tight and clean connections. What is my next step. It seems to me that the Univolt device, the dude that humms is behind the wall that the Low Voltage Distribution Panel is attached to. I can see through cracks in the wall something blue behind the wall. How do you get to that? Do you have to take the whole bloody wall out somehow to get to the Univolt to trouble shoot further? Are their further ways I can take meter readings at the Low Voltage Distribution Panel Proper that my shed some "light" on this very dim/dark subject. Any suggestions will be deeply appreciated. Please respond. Still stumped in Indiana,Randy Wilson

[john hd]

randy

take your fluke to the front panel of the univolt. the blue thing.

do you get 12 volts at any of the terminals?

john

[3Ms75Argosy]

Randy - where is the univolt? Is it in a closet? Can you post a pic? It seems like you can't actually get too the univolt. Is there voltage at any of the terminals that you cleaned?
Marc

[wahoonc]

In the 75 Sovereigns the Univolt is under the closet floor on the curbside. It takes a bit of work to get to it. IIRC the closet floor is either screwed or riveted in. I would go ahead and ditch the thing and get a new converter from www.bestconverter.com The Univolts can be repaired but I can do without the hum.

Aaron

[overlander63]

Originally Posted by wahoonc

In the 75 Sovereigns the Univolt is under the closet floor on the curbside. It takes a bit of work to get to it. IIRC the closet floor is either screwed or riveted in. I would go ahead and ditch the thing and get a new converter from www.bestconverter.com The Univolts can be repaired but I can do without the hum.

Aaron

If you are going to spend hours diagnosing the problem, only to find you need a new Univolt, it was a massive waste of time.
Since his Univolt is humming, there is a possibility it can be easily repaired, if only he can get to it. If it cannot be repaired, he had to dig it out to replace it anyway.
Then again, I am mostly deaf, so a hum doesn't bother me, my ears ring all the time anyway.

[dwightdi]

Look closest you can get to the univolt to verify you have voltage. Use a pin to puncture thru the insulation if you must. Then use start using your fluke to measure for voltage drops. 12 volts means you have no continuity over that fuse. Common problem. Then start looking at your grounds. Bad low side will also result in no charging.

None of this caused your battery to go flat over night. You have something on (maybe you had the termastate turned up above 45 and it turned on overnight) Maybe there is a short someplace else. Take all the fuses out and turn everything off and then ohm check all the lines to locate which one is the problem. Once you isolate it to one circuit the real fun starts because there are many possibilities for failures on each one and it is very time consuming to chase it down.

[Randy Wilson]

randy

take your fluke to the front panel of the univolt. the blue thing.

do you get 12 volts at any of the terminals?

john
__________________
I did ever possible check on the Distribution panel but I couldn't get to the Univolt proper....read on.

John to really see the univolt I had to remove the Univolt Low voltage distribution Panel, which was attached to a piece of paneling and screwed to the inside closet wall. This panel is attached to the closet wall. With it removed you can get a better view of the AIRSTREAM UNIVOLT BATTERY CHARGER AND POWER SUPPLY (MADE BY LITTON) as it says. It is a little longer than a car battery and is blue. It actually sits behind the bathtub right next to the outside wall. It is elevated about 6 inches from the trailer floor proper. And is bolted onto this peice of plywood with 5/16 inch pointed up bolts with a nut and a jamb nut. All the wired going into the Univolt are smashed up next to the outside wall and you can't see and check anything in this manner. Separating the Univolt from the bathtub is a piece of sheet metal with insulation. If I cut away a portion of the wall I might be able to get my hand in a hole and unbolt the unit (maybe). Another problem where the battery cable comes from the Univolt to the battery storage compart ment. It looks as though a person would have to grind rivets and tear out that internal plastic box that the battery sits on. Has anyone on the forum ever been in my predicament? And further let's say I would go to my local Airstream dealer. And I needed a new Univolt. I wonder How many bucksters that would cost for a Dealer to perform such a feat? Please respond. Randy Wilson