Converter Problem

[alan]

I just installed a WFCO 65 amp converter to replace the Univolt in my trailer. Everything seems to be fine, except that the interior 12V lights flicker when the cooling fan in the converter runs. The rate of flickering seems to be proportional to the speed of the fan. If I disconnect the battery, there is no flickering when the fan runs. I replaced both batteries this weekend and the problem continues. Anybody have any ideas on what could be causing this problem?

[Safari Tim]

Alan, I'm not familiar with the WFCO unit yet.

My advice would be to check the ground connections for the converter, battery and trailer wiring. Also make sure the size of the wire from the converter to the battery is large enough and as short a run as possible. I'd say #8 or larger wire at a very short distance would do it. Further away, run a larger wire, ie. smaller gauge number.

Good luck, and let us know what you find.

[alan]

The new installation is basically a replicate of the original Univolt. The new converter uses the same chassis ground and the wires are the same size as used to connect the Univolt.

I did have to change the plug-in for the converter from a standard 15 amp to a 20 amp plug (even though the specs for the new converter show a maximum load of 13 amps).

[Wabbiteer]

When you say interior lights, are they incandescent or fluorescent?

[alan]

The interior lights are incandescent.Two other things I have observed:1. Lights plugged into the 120v outlets also flicker when the converter cooling fan runs.2. If the battery is disconnected, all lights work fine with no flickering.

[Wabbiteer]

Some general observations...

Somewhere current is being limited but that may be a function of the charging algorithm used by WFC, so a flicker may just be the nature of the converter when supplying a high charging current.

With losses that unit may be drawing 10 amps of shore power and somewhat sensitive to circuit leg length and wire guage, what are AC voltage readings when unit is charging? Anything else on that circuit (or even 120V side of 220V utility feed) that could be upseting the power factor? Standard household stuff like refrigerators, freezers, electronic power supplies, ballasted lighting, running motors all could be competeing for the surge currents your 65amp charger requires.

It appears the batteries are not fully charged - use of a hydrometer to check specific gravity of electrolyte is the only way to 'know' what is actually happening. Record findings & familiarize yourself to the relationship between specific gravity and charge voltage for your new batteries to see how they age over the next few years.

The WFC charging logic only allows a 4-hour bulk charge before reducing output voltage so the batteries are likely still current hungry, especially if you are charging two at a time. Boiling electrolyte is not a bad thing unless it continues for days on end, remember to add distilled water to replace any lost. It could be weekly, or monthly, or longer service intervals depending on use. You could interupt 120VAC feed after 1st 4-hour cycle and thus reset the micro-controller of the converter to restart bulk charge cycle if needed.

http://www.bestconverter.com/assets/...9800manual.pdf

[alan]

Voltage at the house plug that the trailer connects to is 120. Voltage at the trailer interior plugs is also 120, with the converter connected, charging, and all of the interior 12v lights on.

I checked the batteries with a hydrometer. All cells are fine.

I have checked all ground and power connections at both the incoming 120v panel and the 12v power distribution panel.

At this point, I am thinking of replacing the circuit breaker for the 120v trailer circuit (can't hurt). It's 20+ years old with ground fault and maybe it has internal corrosion.

[azflycaster]

alan ~ I am stumped by the problem as you discribe it. 2 things do come to mind. Is it possible that you reversed two of the wires when you replaced the 15 amp plug with a 20 on the new box? Could the new convertor be bad?

[balrgn]

Originally Posted by azflycaster

alan ~ I am stumped by the problem as you discribe it. 2 things do come to mind. Is it possible that you reversed two of the wires when you replaced the 15 amp plug with a 20 on the new box? Could the new convertor be bad?

I am too, interesting problem. Have not heard of that brand.

[GlenCoombe]

Interesting problem. I'll be anxious to hear how it's resolved. I've just been back and forth with Bestconverter.com over the weekend looking to replace the hummer in my coach.
It sure sounds like AC current. I'd be calling the supplier and getting their take on this problem.
Please let us know how this resolves.

[68 Overlander]

Hi Alan,
I presume we supplied you with the converter but I can't see your last name so not sure. I honestly don't know, nor does the factory as to what is causing this. It might indeed be the converter and I will gladly replace it if it is but lets make sure.
A couple of things I would look at although maybe a shot in the dark. First, the fuse that protects your light circuit, is it loose or corroded? Try replacing it. Another thought is the connection at the converter lugs, are they tight and not partially crimped to the insulation of the wire.
After you have ruled out the breaker you mentioned, also check the output voltage, it should be steady 13.6 with and without the batteries connected unless it climbs into the bulk mode when you connect the batteries and then like mentioned it should only last a max of four hours.
We had a PD9160 do this about a years ago and the owner never called back so I don't know what the final cause was. He never retured it under warranty so I assume he found the cause.
Let me know when you have ruled all the basics out and I will send you a new converter immediately.
Randy

[alan]

The last name is Whitmyer and yes, I did buy the WFCO unit from bestconverter.com.

I have been working this issue with tech support at WFCO for the last week or so.

I have checked to make sure the problem isn't on the 120v side of the system. I replaced the GFI circuit breaker that feeds the converter, but it had no effect. I have also checked all of the 12v and 120v connections to make sure nothing is loose.

Today, I used an oscilliscope to try to pinpoint the problem. I checked the receptacle in the garage that I plug the trailer into and got a smooth sine wave. After plugging in the trailer and turning on enough lights to cause the converter fan to run, I checked receptacles in the trailer as well as in the garage. All receptacles now show a voltage fluctuation. Since the voltage at the main power plug in the garage is fluctuating, I am inclined to be suspicious of the converter.

One other thing I tried - I disconnected the chassis ground wire on the converter and reconnected it. Prior to doing that, I had been seeing 13.7 - 13.8 volts at the 12v receptacles in the trailer when plugged into shore power. After reconnecting the chassis ground, voltage jumped to 14.4v for awhile, and then fell back to 13.7 or so.

Prior to installing the new converter, the original Univolt was in the trailer and seemed to work ok (other than the hum).

I missed a call today from tech support at WFCO and will call them tomorrow to pass on my lastest findings.

[Safari Tim]

How about getting the biggest gauge extension cord you have and bypass the trailer wiring all together by plugging the converter into it and the extension cord to your house somewhere.

It might narrow it down to something in your trailers wiring.

Just a thought.

[Excella CM]

If your house current lights flicker when the batteries are trying to charge, it seems like you have a severe current loss within the trailer's 120VAC system. The small load from the converter cooling fan is using most of the available power, so there cannot be much available. Try making a piece of toast and see if there is enough power for the toaster. You could use a lamp connected with a cube tap where the trailer is plugged in. If the external lamp flickers, then the supply from the house fusebox is defective. Otherwise, if an external (like a drop light) is bright, then the trailer wiring has a problem. Look for something that is hot or smells hot!

[68 Overlander]

Alan,
Tim has a good thought. I would try that. If you still feel it is the converter, just call me and another is on the way pronto.
If the second one does it, well Houston...we have another problem but I will be here to help if I can.
Believe me when I say I have heard it all when people upgrade their DC electrical systems but it usually goes without a hitch.
Reminds me of my grandfathers elbow pain following his hip replacement.

[alan]

Ok, I tried everything suggested as well as all of the recommendations I got from WFCO tech support, nothing changed. Bottom line, Randy from bestconverter.com sent a replacement unit this past week which I installed. The flicker problem with the 12V lights is virtually eliminated. There is still a bit of flicker on the 120v table lamp, but I can live with that since I dry camp almost exclusively.

Thanks to all who contributed their ideas to solve this problem (a special thanks to Randy for his help).