Univolt Switch??

[nohillgrish]

A few years back when I purchased my 1987 Excella trailer I noticed a switch behind the left front curtain labeled "univolt switch". I had always assumed the univolt operation was automatic when plugged in to 110. I, therefore, just left it in the "on" position. The unit did already have a solar system. In subsequent reading about solar systems, I read something that made me think this switch might have something to do with the solar system. Perhaps the "on" position when using solar power would let me use some appliances that I otherwise would not be able to. I experimented with that idea last night, and don't believe that's the case. One thing I have noticed is that if the switch is "off" when plugged into 110 I can use the 110 side of plug ins, but lights appear to get brighter when I turn the switch "on". My two questions after all this rambling are: 1)Does anyone have an idea what this switch does, and 2)In what position should it be on when running off solar vs. 110?

[68 Overlander]

Old Univolts with large transformers will hum. At night its annoying to some people. Its a shut off switch and the lights are dimmer because the battery supplies lower DC volts than the Univolt. It was an option for many years.
When running off solar (or not plugged into shore power) there is no power to the Univolt anyway so in that case it doesn't matter.

[nohillgrish]

Randy,
Thank you very much for prompt reply. Your response makes perfect sense. I have been an active reader of the forum for some time, and can't believe I never thought to ask this question that has been bugging me for so long.

[Driver1]

Hi Stray & Randy,

On reading your posts, I was reminded of something I read in my manual about that switch. I ALWAYS leave it ON.

I found and scanned that part for the attached picture. Notice the caution about blowing radio fuses if the switch is off while plugged into shore power.

Walt

[Mike Leary]

Huh, I've been turning off the breaker for the Univolt every night for at least fifteen years
and have blown nothing. It's a GFI breaker, so maybe different in mo/hos.

[68 Overlander]

Maybe somebody can explain this that knows why. What I know is there should be no reason for it and know thousands of Airstreams have this option. My 81 had it but I disabled it when I replaced the converter since the new converters don't hum and I see no reason to disable it, less a disconnect for storage and even that doesn't make sense anymore.

[nohillgrish]

Walt, thanks for scanned info on the univolt switch, and thanks Mike for easing my worries about what I may have blown. Everything still seems to work fine so, maybe as Randy suggested, someone may have disabled this system before I got the trailer. I am even more suspect that the original univolt was replaced as the one I have doesn't seem to make any noise at all--whether I have the switch on or off. I really appreciate the insight you fellows have shared.