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Old 10-26-2010, 07:06 PM   #1
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1974 25' Tradewind
marion , Virginia
Join Date: Oct 2010
Posts: 1
electric/battery problem

i am a fresh airstream owner.

i bought a 1974 land yacht. it is in really good shape and when plugged in to electric outlet everything works. water pump, toilet flush, all lights, plug ins, ac, furnace, etc. i was amazed
there is a switch near front door that apparently controls the "master control panel" (?proper term) above the stove. when this switch is "on" - the water pump switch and battery power meter located on the "master control panel" both work (when plugged in). this tells me it sees the battery.
but sadly when the trailer is unplugged NOTHING works.
another weird thing is, when hooked to the truck, if the truck key is "on" again - everything WORKS!!!

but some how the battery will not run anything. we purchased a brand new battery just last week - we have had the trailer two weeks.

i have replaced all fuses that i see in the "univolt" thing.

any ideas what could be preventing the trailer from running on battery power?

i truly appreciate any advice you may have!

thank you!
Jenny Patterson

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Old 10-26-2010, 08:21 PM   #2
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1974 27' Overlander
Sault ste Marie , Ontario
Join Date: Jun 2004
Posts: 165
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electric/battery problem

Have a 74 overlander that had a 50 amp fuse in the negative line (black) mounted on the wall between the battery and the fuse panel with the univolt. Does your unit have this and is it good? Also had a problem with one of the wire connections at the same fuse. Good luck with this.

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Old 10-31-2010, 08:10 AM   #3
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2006 25' Safari FB SE
1972 25' Tradewind
Houston , Texas
Join Date: Feb 2009
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Congrats on the 74 Tradewind, I had a 72 (til it was stolen in Sept.) and they are great trailers, right size, lightweight and easy to fix. I take it your univolt system in in the bath area, mine was in the closet. Do you have an updated charger- The Intellipower Chargers (you can Google that) are a popular replacement for the original "blue box" Univolts. Many people keep the fuse panel in the Univolt and just replace the charger. I am attaching a copy of the Electrical Service Manual, it actually is for a 74 so I hope it helps you out.
Attached Files
File Type: pdf 1974 AS Service Electrical System.PDF (1.22 MB, 35 views)
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Old 10-31-2010, 08:30 AM   #4
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1971 25' Tradewind
1993 34' Excella
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I would be surprised if the switch near the door controls the control panel. There is a switch in the location you describe that gives you a second switch so you can turn on the lights in the galley as you enter the trailer..

Pretty much everything in the trailer works on 12v, either 12v from 110 being converted through the Univolt or the trailer battery. There is also a hot 12v line that runs to the trailer from the tow vehicle to charge the trailer battery when towing. That would explain why you have power with the key on. Then you are running off the tow battery.

The only thing I can think of is for some reason the battery is not connecting with the Univolt. Look for a fuse (as mentioned above) or a battery disconnect switch betwen the battery and Univolt. Check the battery has a good ground. Still no power? Check the battery lines coming into the Univolt have power with a test light.
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Old 10-31-2010, 09:57 AM   #5
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1976 27' Overlander
Stuarts Draft , Virginia
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Posts: 28
Oh wow I had the very same issue with my 76 Overlander just recently. I was told to check the ground on the distribution panel. This is the fuse box panel that distributes the 12v to all the 12v devices. It usually sits beside or close to the Univolt. I tightened the screws that mount the fuse panel to ground and then everything worked connect to battery or shore power. I hope your issue is as easy to fix as mine was.
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Old 10-31-2010, 11:35 AM   #6
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In mechanics, electronics, and in life . . . when something is designed to work, and it doesn't, I need to divide the divisions. That is, to visit the elements individually. I need to list my assumptions and figure out which one of them is flawed.

Trailer electricity is basically power source, fuse, wire, switch, fixture, and ground. That's 6 things to check. The tools are alternate power source (like a small battery charger), a multi-meter ($10 at home center), and a test light ($5 at auto store).

I'm with mountainman1. I'd start by checking the ground.

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Old 10-31-2010, 11:30 PM   #7
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1972 25' Tradewind
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Vibration affects a lot of things in a Vintage coach. I found in mine the most difficult things were the "it works one minute and then doesn't another.". I found the fuses come loose in the holders after travel. Lights don't work some times cause the fixtures are old or the bases are corroded. So as said above a good tightening down or a jiggle of a wire, can fix or track down a problem. I would even hit a fixture with my hand and it would come on.
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Old 11-01-2010, 12:08 AM   #8
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1983 31' Airstream310
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Typically an old Airstream has seen a lot of neglect and ignorance in 35 years. Based on what you have said I would guess that the battery is not connected to the panel in the Univolt. Maybe the person who installed the battery didn't check that it worked. We know the Univolt is supplying power to all the circuits, but there is probably no connection to the battery.

Check the voltage at the Univolt (from any of the fuses to ground) when it's plugged in, should be around 14 volts (and zero when it's not plugged in). Check the voltage at the battery, it's probably around 12. These two voltages should be the same when the Univolt is plugged in (maybe half a volt less at the battery, due to losses in the wire when there's a lot of current going into the battery. ) Trace the wires from the battery, be sure the negative post is solidly connected to the frame of the trailer, and the positive post should run in heavy gauge wire to its own fuse at the Univolt. Sometimes all the fuses are inside the Univolt (they are in my 71) and sometimes there are others in line or in a separate panel, depending on what "improvements" have been made.

According to the diagram in the post above, there's a circuit breaker in series with the battery. I would check that and the wiring to it, first.

You don't need to work on this often, but every Airstream I've been involved with has had hairball wiring in one place or another. I'm an electrical engineer so it's easy for me, and really it's easy for anyone who's patient, but a lot of people are afraid of electricity, and they really needn't be.
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Old 11-01-2010, 02:21 AM   #9
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i don't know if it applies here but some trailers had quick disconnect cables in the battery compartment. if you have them, check the connections.

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