Univolt question

[overlander76]

When I came home from work the last two days, the fan on the univolt was running. It seems to run alot. The battery was just replaced a few weeks ago and there were no 12 volt devices running all day. The camper is plugged in to AC. Is this related to the heat? It was 95 out today. What are the signs of a failing univolt? Is the univolt just a glorified battery charger?

Thanks for your help
Brian

[garry]

I don't think my univolt has a fan. However; the univolt will over charge batteries and boil the water out if left on all the time. I installed a kill switch on the positive side of battery so the univolt is only charging when I want it to and the AS can be pluged in all the time.

Garry

[overlander76]

Thanks for the reply! I have never seen the univolt so I can't say for sure that it IS a fan, however I'm almost sure it is. Today I felt the battery and it was cool to the touch. The plug for the univolt is under the sink, I guess I could unplug it when not needed. Today I turned it off at the AC panel and right back on and it seemed to fix the problem. The fan noise quit. It never seems to go on at night while sleeping.

I see people on this site swapping the univolt out for another type of charging system. That might be an option in the future if the univolt takes a dump.

[overlander76]

I wonder if anyone else has a fan on thier univolt?

[3Ms75Argosy]

Hi, my univolt will "buzz", but it does not have a fan (that I've noticed). Also, in my Argosy, the univolt is back by the bathroom, and I have not noticed a plug that will connect / disconnect it. Is it possible that you have an aftermarket one?
marc

[thenewkid64]

Marc,

There should be a plug, but you would have to follow the wire to the wall. In our 76 MH there is a single breaker that only controlled the univolt. The univolt is buried in the bathroom counter where the only access is via an access panel. The breaker is how we turn off the univolt. In some Airstream trailers there is a wall switch near the univolt that will turn off the power to the outlet that the univolt is plugged into. It has no fan.

The 78 MH has a replacement unit, it is a Magnetek. It has a fan and the fan runs based in the internal temp of the charger. The battery may be cool to the touch, but if you are running a large numbr of lights, or fans the load may be enough to reach the set point of the internal fan control.

[overlander76]

My univolt is behind the oven to the right. I wondered if it was supposed to be there or if somone just put it there. So I read through the 76 service manual and it places it behind the oven, above the battery box. The 76 Excella with the rear bath it shows it on the right side of the bathroom (passengers side).

The plug to the univolt plugs into an outlet under the sink. You really have to reach back there to unplug it but so far this is the temporary solution I'm using.

Other thing I found tonight is the water tank leaks if you fill it up too much. It was dripping at the access panel under the trailer. And the plywood by the furnace was wet!

Thanks again for all who have helped answer my questions!

[Inland RV Center, In]

Some of the larger capacity Univolts did have a built in fan.

The 75 amp model, in particluar, had a fan.

The fan only ran when excessive heat was generated.

At larger outputs, some heat is generated, simply because of the nature of any charger, and it must be dissipated, to prevent burnout.

Andy

[overlander76]

I got out the flashlight and mirror today and the "univolt" is a Magnetek. I believe this to be an aftermarket unit? What does this group think about Magnetek? Should I spring for a Univolt someday?

Thanks for the continued help...

[Coloradobus]

Can '60's vintage Univolt handle todays gel-cell battery or an AGM(ABsorbed Glass-Matte battery. We have AGM's in our motorhome)non-Airstream and they have much more life before charging. And they charge up full just like the first time, they are not prined to much sulfation. Problem is, when charging they are demandingly thirsty.

[Inland RV Center, In]

The Magnetek is Airstream's univolt. Just a different manufacturer name.

Andy

[gvanman]

Originally posted by Coloradobus
Can '60's vintage Univolt handle todays gel-cell battery or an AGM(ABsorbed Glass-Matte battery. We have AGM's in our motorhome)non-Airstream and they have much more life before charging. And they charge up full just like the first time, they are not prined to much sulfation. Problem is, when charging they are demandingly thirsty.

quote:
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Coloradobus,
Hi, I am new to this forum, but have been in the battery business forever and your post seems confusing! You say that your AGM batteries charge up well, but are thirsty - this is where the confusion comes in as AGM batteries are maintenance free and are not made to have water added! The same applies to Gel type batteries as well. I don't know if the vintage Univolts are adjustable, but it might be worth checking into to see if they are. If your battery is using a lot of water, then it means that it is being over-charged and this will reduce its life. I would imagine that the Univolt was originally designed to re-charge flooded type batteries but it must have some control to cut back the charge current as the battery voltage rises otherwise it will just be on constantly leading to 'thirsty' batteries that will fail prematurely!
In order for the Univolt to be able to cope with AGM and Gel type maintenance free batteries it would have to be even more precise in its output control or these type batteries will be over charged, causing them to lose their precious moisture and fail quickly.
I have a maintenance free battery on my Argosy Minuet and the Univolt is run from a switched socket - I switch this on and allow the battery to charge for a couple of hours now and then but always switch it off to protect the battery.
I will do some digging and see what I can come up with regarding the Univolt specifications.
Cheers!

[Coloradobus]

GVANMAN,
What I meant by the AGM being a thirsty battery, let me re-phrase . We have been told by our motorhome converter, that the AGM battery (Lifeline brand) in general when its charging, it wants all its power back, NOW. They require high input for re-charge.. and am afraid a vintage Univolt may become toasted by the AGM.
Because of this reason, we have decided to obtain the largest reserve capacity flooded battery(Goup 27) in combination with an 80 watt solar panel. Most of the time, the Globetrotter will not see a conventional campground with amenities, like electric hookup. We are reconditioning the A/S with current boondocking technology.
We are also removing the old Armstrong A/C and putting 2 Fantastic fans in place of the original vents. Have to replace the vent lids and one fan motor anyway

Thanks Gvanman for you input. If you find that an older Univolt will not go up in smoke, we may change our minds and anty-up for the higher priced Absorbed Glass Matte (AGM) .