My converter noises

[Gary_and_Tammy]

We are getting a strange screeching from our converter, it is not fan noise, and it is not humming loudly, this is a full out screechy noise sometimes high pitch and sometimes lower, definetly electronic, and it is not an alarm.
I replaced this converter 4 or 5 years ago when we noticed the refrigerator was switching on and off continuously, and we had no lights inside the camper.
Now this is different, I checked voltage, I checked fuses, everything checks out right, I cannot "Make" the noise happen so I have not checked voltages when it screeches.
I tried googling this like a mad man but nobody is coming up with the same sound as this.
We did notice the lights blinking, not flicker or dim, but a blinking, with the air conditioner on when we were at a campground this past weekend.
Our battery level showed low but when we got home the next day the battery was fine.
I dont mind replacing the converter again, but I dont want to spend the money if I dont have to.

Thank you all for any and all help.
Sorry if I left out anything this is my first post to a forum

[SEMO_Mike]

The converter in my 1993 hummed like crazy when I got it, which drove me crazy. I took it out and put in a multi-stage Progressive Dynamics. Works like a champ and doesn't make a sound. It also weighs less than 1/2 what the old one did. I keep the old one in the shop for a 12 volt power source when I need to check things.

[Gary_and_Tammy]

That noise in the video is actually quiet compared to how loud mine gets.
It is loud enough to wake you up at night, and you can all guess who's side of the bed the power box is on.

I do like the looks of the Progressive Dynamics PD4655V, but if its the battery then I dont want to spend more money on that, unless it would make a new battery last longer.

[GordonThree]

Gary and Tammy wrote:
https://www.youtube.com/watch?v=M7tJeGOlzzA

clicky

That noise is nothing to worry about. I still suspect the problem is with your battery, or the wiring / connectors.

Shore power is 60 hz, which is a vibration. Loose windings in an inductor (or laminations in a transformer) can make this noise.

If the battery and connectors all check out, ditto the recommendation from an earlier poster, replace with a 3-stage converter / charger.

[Gary_and_Tammy]

https://www.youtube.com/watch?v=M7tJeGOlzzA

[Gary_and_Tammy]

I finally found a youtube video that has probably the closest sound to what mine will do.

The best listen is like 35-40 seconds into this video.

***Link Removed***

[tenbear]

I looked at bestconverter.com and see that the 7155 is a single stage converter. If you do decide to replace it you should consider replacing it with a modern 3 stage converter. They will charge your battery much faster and will not overcharge the battery. Have a look at www.bestconverter.com.

[ScottG]

Could also be the laminations in the transformer buzzing. They can be good for years until the coatings brake down.

[Gary_and_Tammy]

when I get home tonight I will check the battery, I do not have a hydrometer but I do have a portable refractometer that you can check a battery with.

The noise is random, with air conditioner on or off, for instance yesterday after getting home from out trip I plugged camper into 110, and started emptying our clothes/food, etc, and when we went back in for the second load we could hear the screeching, I walked over to the box and it stopped, very random as there were no lights on or anything.

The unit is a Parallax 7155

[1995brave]

What is the make and model of the converter?

[kerrlakeRoo]

Also wondering if it makes this noise when the AC cycles on, Voltage drop on AC startup could be causing the circuits to make some sounds.

[GordonThree]

Could be capacitors or inductors "singing" due to poor design of the circuit.

I would double check your battery, use a hydrometer not just a gauge on a panel. Even if the converter was malfunctioning the lights and fridge will be powered by the battery and shouldn't be blinking.