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jeff&jess · 02-21-2007, 06:31 PM

Hello, we bought our 1974 31-ft Sovereign last summer and hadn't tried to run it off the battery til now. The battery that came with it gave us nothing at all, so we replaced it. Now with the new battery, when we unplug from the AC hookup all we get are (1) the panel lights, and (2) the water pump... (I note that both of these things are operated from the control panel above the stove.) None of the DC lights or outlets (which all work fine when we're plugged in to AC) work from the battery. Is there a switch, a fuse, something we need to look for....? Can't tell from the manual. Thanks for helping!

Jesse

joqin · 02-21-2007, 06:40 PM

there is an AC to DC switch somewhere. mine is right next to the main AC box or there is a switch near the battery. I have both. hopefully, someone with a 74 will jump in and tell you exactly where these are . jq

AYRSTRM2 · 03-02-2007, 01:40 PM

I believe, based upon an answer you got in another thread, that this switch is not your problem. First thing to do is make sure you have your battery hooked up properly, positive and negative-wise. I think you already did, but just do that. Also, visually inspect all of your fuses or breakers, depending on which you have. Especially check for an inline fuse coming from or near the battery cables.

See, here's the thing: Your Univolt/converter is hooked in parallel with your battery. To the trailer, the univolt and the battery look like one power source, ie black box. The only real difference between plugged and unplugged from shore power is when the battery is discharged. If the Univolt is giving off bad voltage but the battery is strong, you will have normal voltage for a while, just the battery will discharge even when plugged in. Therefore, I suspect that your battery is giving off lower voltage than the univolt.

I recommed you hook a volt meter to the + and - wires that come into your 12 VDC panel. Unhook the negative terminal on the battery. Plug in and see what your voltage coming in is. Now unplug and hook back up the battery. What did you get? Here's what you should have seen, approximately:

Univolt: 13.6vdc
Battery 13.3 to 11.00vdc, if the battery is good. (should be the higher number)

Any differences and you have something wrong with one of them. If not, then you may have faulty fuses or corroded wires. Let us know if you test the voltages and what you find out.

TomW · 03-02-2007, 01:52 PM

Quote:

Originally Posted by AYRSTRM2

... you may have faulty fuses or corroded wires...

Karma to you, John. Great post!

I cleaned corrosion from my fuse holders, and from where 12 volt wiring was connected with wire caps.

Tom

lewster · 03-02-2007, 06:30 PM

Most 12VDC power supply problems that I find are directly related to bad connections. That is to say, corroded, loose or frayed terminals or connections will wreak havoc on the transmission of DC current. Check them ALL and clean and tighten them. You'll be a happy camper!

AYRSTRM2 · 03-03-2007, 08:01 AM

Ok, so on the '66 models I feel like something of an expert. On 74's, not so much. You should read this post by 68Overlander, something of an Airstream electrical expert in general. The way he describes the situation is very interesting, and if you trailer is set up like he describes then that could aid in finding your problems.

davidz71 · 03-03-2007, 11:43 AM

Quote:

Originally Posted by jeff&jess

Hello, we bought our 1974 31-ft Sovereign last summer and hadn't tried to run it off the battery til now. The battery that came with it gave us nothing at all, so we replaced it. Now with the new battery, when we unplug from the AC hookup all we get are (1) the panel lights, and (2) the water pump... (I note that both of these things are operated from the control panel above the stove.) None of the DC lights or outlets (which all work fine when we're plugged in to AC) work from the battery. Is there a switch, a fuse, something we need to look for....? Can't tell from the manual. Thanks for helping!

Jesse

Jesse,
Have you located your 12 volt distribution fuse panel? My '77 Excella 500 had the panel located in the center front wall of the trailer under the window and within the entertainment center. It has four 50 amp fuses, one for each of two battery + lines and one for each - line. It also had five 20 amp fuses that went to the 12 volt lights, water pump, fans, etc. There were also four 15 amp fuses which protected the taillights, turn signals, etc. and one lone 4 amp fuse which controlled the "power on" circuit in the panel. Locate this distribution panel and check for tightness/cleanliness as well as functioning fuses. Hope this applies to your '74 and helps.

68 Overlander · 03-06-2007, 07:17 PM

With a new (and charged) battery, this should be pretty simple and I think David and Lew are on the mark. Unless you had some serious rats chewing through wires, I can't understand how it could be other than fuses, corrosion, or a fouled up fuse panel. Like John said, a simple voltmeter will tell you if each DC circuit is getting juice. The fuse panel can be a bugger to get too sometimes but you will have to check it.