'76 Converter Humm

[Mr. Decent]

On this '76 31' Excella I am working on, the electrical system seems to be in pretty good shape, although, I believe it is the converter? behind the kitchen counter next to the door, It has a Loud Humm, any ideas for simple solutions to lesson or get rid of the humm? Thanks for any input

[easyride]

Buy a new converter,I think all the old ones hum.Dave

[Lumatic]

Ummm, Hummm, what hum? Hmmmm?

You can't beat em, join em mmmm Take up chanting. Ommmm.

All seriousness aside. The only way to get rid of the hum is to replace the Univolt. they all humm. They were OK in their day but are not effective chargers and lead to premature battery failure.

[Inland RV Center, In]

Originally Posted by Mr. Decent

On this '76 31' Excella I am working on, the electrical system seems to be in pretty good shape, although, I believe it is the converter? behind the kitchen counter next to the door, It has a Loud Humm, any ideas for simple solutions to lesson or get rid of the humm? Thanks for any input

The hum comes from the metal laminations in the transformer moving at the frequency rate of 60 cycles.

You can repot the transformer in varnish and it will stop the hum.

All transformers in power supplies, are potted, in one way or another.

Andy

[Mr. Decent]

thanks for the info, at least I know it's 'normal'

[Squid]

My old univolt hums also. Andy what does "repot" mean? I went and bought the Intlli-Power 9200. Haven't take it out of the box yet. It was alot of $. cant decide to go ahead and make the switch. the Univolt seems to work other than the hummmmmmmm. Kinda of obnoxious! To repot or not to repot, that is the question>
Squid

[Inland RV Center, In]

Originally Posted by Squid

My old univolt hums also. Andy what does "repot" mean? I went and bought the Intlli-Power 9200. Haven't take it out of the box yet. It was alot of $. cant decide to go ahead and make the switch. the Univolt seems to work other than the hummmmmmmm. Kinda of obnoxious! To repot or not to repot, that is the question>
Squid

Transformers are potted in varnish, so that the laminations cannot move.

When the laminations move, or are loose, you get the hum.

But, before you get into the repotting, sometimes just tightening the screws on the transformer will also stop the hum.

If that fails, then you can repot.

Take the transformer out of the Univolt.

Immerse it in a pot of varnish, that has a cover or lid.

Rotate the transformer to a different position, once a day, so that any air bubbles will float away.

After a week or so, you can remove the transformer from the varnish, and let it hang from a couple of the wires, so that the excess varnish drips away.

Let the varnish cure out, for a few days, so that it's as dry as it can get.

Reinstall the transformer. You will not hear the hum again.

Obviously, commercial transformer potting, is much faster.

Andy

[Lumatic]

Originally Posted by Squid

My old univolt hums also. Andy what does "repot" mean? I went and bought the Intlli-Power 9200. Haven't take it out of the box yet. It was alot of $. cant decide to go ahead and make the switch. the Univolt seems to work other than the hummmmmmmm. Kinda of obnoxious! To repot or not to repot, that is the question>
Squid

Another consideration: The Univolts put out 13.something volts all the time when plugged into shore power. Univolts frequently overcharge batteries causing loss of electrolite and premature battery failure (battery boiling). New converters have several automatic phases and are much more battery friendly, especially for AGM batteries.

[Squid]

Thanks for the repotting insite! Think I will take the easy way out go ahead and install the 9200.

[Squid]

What is a AGM Battery?

[Lumatic]

Squid,
To put in the Intellipower you will have to salvage the fuse panel from the Univolt or put in a new one. I took out the guts of my Univolt and cut off the back end of the Univolt cover and attached the Intellipower to the old Univolt base. Then wired the Intellipower leads into the old fuse panel. Here is a photo without the cover. There are other ways to do it.

An AGM is a sealed battery you don't have to add water to. That also means no sulfuric acid off gassing and no spill concerns. They cost about 3x the price of a regular flooded battery, but also last a lot longer.

If you have only the one original battery configuration you might want to consider adding a second or a larger battery. A lot of folks put in 2 6 volt golf cart type batteries wired in series to give you 12v. I put in a 12v zize 4D AGM battery which gives me 200 amp hours.

There is a lot of other information in other forum threads.

[Squid]

So AGM battery is sealed? Does that mean it is a gel-cel? The specs on the 9200 say's "For use with lead-acid and not gel-cel batteries".
I love the low maintenance of the sealed batteries. I have 3 in my boat. Don't have to do a thing except charge the trolling batteries ever so often.

[azflycaster]

AGMs are sealed, but are not gel celled. They still should be vented because they can out gas if they get hot.
VRLA - Wikipedia, the free encyclopedia

[Squid]

So AGM batteries, purchase your local rv store?

[Lumatic]

I forget what the A is for but the GM is for glass mat. I was under the impression they do not off gas. At least I do not see any way mine can let any gas escape. I could be wrong. Check with Randy at BestConverter.com he is a forums member. I think Lewster also sells batteries and converters. The standard for AGM batteries is Lifeline. I bought a Universal which I found out after the fact is Chinese. There are also Optima batteries you can find at autoparts store but I think you may be able to do better.

I have an Intellipower 9245 and have been told it would be OK for AGM batteries. The thing is AGM batteries have a preference for particular charging voltages.