Battery Good No DC Power with shore power off.

[Frank Ross]

I have a 1975 Overlander. The Univolt was not working but the DC circuits worked OK on battery power.

I recently installed a Boondocker inverter and all systems appeared to be working properly.

Finally after having worked on the trailer for over a year my wife and I took our first trip.

As we did not have shore power so operated on battery power. My fridge is a newer model and requires DC power to operate on propane. When we went to bed everything was working properly.

The next morning the fridge was not working and I had no DC lights. I thought that the battery must be dead so I started the generator. Everything then worked well on AC power including DC lights fridge and water pump. I ran the generator for 6 hrs to charge the battery.

When I shut the generator off I had no power. I checked the battery and it was good.

I checked the distrubution pannel and had power on the positive side as well as the negative side. I contacted a test light to the negative battery post and toutched both the positive side and negative side of the distribution pannel. I had power on both sides however the DC interior lights and other DC circuits will not work.

I thought possibly that I had a short in the distribution pannel so replaced it with a new DC fuse distribution pannel. The problem persists.

Would anyone have any idea of what may be the problem? I would really appreciate it if you could help me out.

Frank

[PeterH-350LE]

Originally Posted by Frank Ross

....

I checked the distrubution pannel and had power on the positive side as well as the negative side. I contacted a test light to the negative battery post and toutched both the positive side and negative side of the distribution pannel. I had power on both sides however the DC interior lights and other DC circuits will not work....
Frank

I don't get it, you have +12v power on both the positive and the negative of the distribution panel?? If thats so , you have some serious cross wiring.

[Frank Ross]

I don't know whether it is cross wiring or something to do with the new inverter. When I plug in shore power the DC circuits with the exception of the water pump work. I am at a complete loss.

[PeterH-350LE]

Frank, you say you have installed a Boondocker Inverter. An inverter converts 12v DC to 110 v AC. Is that what you installed? Or did you install a Boondocker Converter, that does the opposite (110 AC to 12vDC)
Either way, I would start with disconnecting one thing at a time.

[jdalrymple]

What kind of test light are you using?

Test for voltage from the trailer skins to the positive side of the fuse panel/ battery lead.


Regards,

JD

[cwf]

Are you run ing fuses or breakers?

[cwf]

Do you have a storage/master switch?

[Frank Ross]

Thanks very much for the comments.

I am using a Powermax Boondocker 4 stage converter charger. The test light I am using is a snapon prob type tester with a internal light. Since having the problem I changed the original Airstream fuse box pannel with a Powerlax Pwr Supply Fuse Distribution Pannel The problem persists.

I carried out some more tests that I will list below.

negative battery to trailer skin light comes on
negative battery to Fuse Box ground Lighe is on.
Positive battery to Skin Light is off.
Positive battery to fuse box ground Light is off.
Fuse box ground to skin light is off.
Fuse box ground to fuse box power lead in light is off.

It almost seems like the positive and negative terminal of the battery are switche but they are not.

I am thinking it may have to do with the ground wire bundle behind the wall pannel.

If any one has any ideas I would certainly like to here them.

Frank

[mimiandrews]

Question:
How did you determine that the battery is good?

Something I noticed in your list of tests:
"Fuse box ground to skin Light is off"

I'm not familiar with the test light you're using. Does "light off" mean there's no circuit (infinite resistance) between the two points being tested?

If it does, then you may have a bad ground connection somewhere. There should be continuity between the negative side of the electrical system and the trailer frame and skin.

Like most vehicles, the trailer uses the frame as the return path (negative) for the DC system.

Ground connections get little respect, and often are bad due to corrosion, paint, broken wires, etc.

[mimiandrews]

There should be continuity between the negative side of the electrical system and the trailer frame and skin.

Let me clarify that. This is true of the DC system only. AC connected to the skin is bad, bad, bad.

[PeterH-350LE]

Have you completely taking the Converter out of the loop to see if anything changes? Not just unplugging it from the wall, I mean disconnecting the + and - from the converter.

[Al and Missy]

My guess is that the ground connection from the power panel to the battery negative is open. Follow the wire from the power panel that should go to the battery negative. I'll bet it has pulled out of a terminal somewhere. On some older trailers there is a fuse in that line, as well.

Al

[TG Twinkie]

Sounds to me like you don't have a connection between the negative side of the battery and the skin/frame of the coach. Do you have any light switches etc in the on position?
If so, the voltage is "standing" on the open side of the ground/common and when you test between the battery negative and the skin, you are getting 12 volts, light on.
You may have a fuse on the negative side. Usually a single fuse holder mounted on the skin if the coach. It may be blown or have a bad connection.
I would disconnect the battery completely. Then disconnect the two wires at the converter. Make sure the wires from the converter are not touching anything.
Then I would connect a battery charger to the battery leads and then connect a jumper wire between the negative battery lead and the skin and another between the ground/ common terminal of the fuse panel and the skin.
The reason for the battery charger instead of the battery. If you have something crossed up. The charger will crowbar and shut down. Not causing any damage. If you use the battery. You might blow something up.
Where does the other end of the battery negative wire connect to?
It needs to be connected to the skin/frame of the coach. There should also be a wire from the Ground/common side of the fuse panel to the skin.
If you are missing either of these connections. Nothing will work.
If you have the battery negative connected to the ground/common of the fuse panel directly. Nothing will work until you connect the ground/common to the skin/frame.

[Frank Ross]

Hi Everyone,

Thankyou very much for all your suggestions and comments.

I worked on the trailer all morning and tried your suggestions but could not correct the problem.

This afternoon I decided to take everything out and start from scratch which I did. Rather than install the new fuse block pannel I installed the original Airstream Fuse block. I hooked everything up as I believe it was when the problem started with the exception of the new converter.

When I checked out the system everything was working properly.

Before connecting the new converter I would like to hear from someone who has replaced their Univolt with a converter as to where they connected the positive and negative wires from the converter to the fuse block pannel. I cannot see how it would make a difference as to which positive and negative connection I use on the fuse block pannel as the their is continuity between alll three negative connector points. The same is true with the positive connector points.

The positive and negative connector studs at the back of the fuse block pannel at this time do not have wires connected to them so I assume that the converter should be connected to these two points.

I would like to hear from someone as the how they have their converter connected to the fuse block panne.

Thanks again for all the great support.

Frank

[Al and Missy]

The difference it makes is that you can have continuity through a 3A fuse, but the converter will blow it if you try to run the trailer through it. You need to find terminals that are directly connected to the battery plus and minus, or at least through a large fuse. That said the new converter should connect at the same point that the original charger connected to the fuse panel. Also, it would be hard to go wrong connecting the new converter directly to the battery, or on the other side of the disconnect switch from the battery.

Al

[TG Twinkie]

The two terminals you speak of are where the Univolt connected and should be where the new converter connects. The positive goes to the terminal that has a buss connected to each fuse. The negative goes to the opposite terminal.
There may be a 30 amp fuse that is labeled "battery". That is where the positive terminal of the battery connects.
Can you post a pic of the Univolt fuse block and one of your new fuse block?

[Jcounsman]

I am a new owner of an As Sport 22, 2019 model. We camped several times but always with power hookups. So when there is no hookup, I can’t figure out how to turn the lights on....I’ve read the owners manual, etc. Kinda assumed this would go automatic when not hooked up to shore power that the battery would take over. What am I missing folks. I am an electrophobe so I don’t know didly about voltmeters, wiring, etc. Assume I am missing something simple or something simply isn’t working!

[AirMiles]

There is a “store/use” switch next to a red light that needs to be switched to “use” to get your lights to turn on. Mine is just inside the door. Switch it back to “store” when not using your Airstream.

[Jcounsman]

Originally Posted by AirMiles

There is a “store/use” switch next to a red light that needs to be switched to “use” to get your lights to turn on. Mine is just inside the door. Switch it back to “store” when not using your Airstream.

Thanks Airmiles...I found a "on/OFF" switch at the base of the bed. It was off and I switched it on...voila...lights...one more thing I now know!