RV Power Converter gone bad?

[mqshaw]

I have an WFCO-8955 power converter in my 2010 Flagstaff Shamrock 21SS trailer. I pulled it out of storage last week and noticed that the battery was dead. So I charged up the battery before we took it camping to make sure that everything runs OK. Unfortunately it did not go so well ... the battery died the second day, while connected to sure power at the campsite. I brought a battery charger with me, so was able to get the battery charged back up for the rest of the trip.

Here is what I have done to triage the situation thus far ...

The AC, Microwave and 120V appliances are working fine on sure power, but i am having a problem with the 12V circuit. When the (charged) Battery is connected, I am getting bright lights in the cabin, and the fridge, radio, etc. are working fine. But when I disconnect the battery, so its running on the output of the power converter only, the lights glow dimly, and then start to pulse as I turn on more light circuits.

I have taken a multi-meter to the system and this is what I am reading

120V AC coming out of the circuit breaker, going into the power converter.​

With the battery connected, power converter running

13.5V on the DC side of the power converter with no 12 appliances running​

12.9V on the DC side with appliances running.​

​

With the battery disconnected, power converter running

​

~13.1V on the DC side of the power converter with no 12 appliances running​

~3.8V on the DC side with appliances running.​

​

I did disconnect all of the 12V fuses to test for short circuits, I found that one of the lighting circuits appears to have a short to the trailer ground. But, even with this fuse removed, the cabin lights still glow dimly when running only on sure power.

Question ...

Does this imply that the power converter is in need of replacement of is the problem elsewhere? I have identified the circuit that has the short and isolated it, and can run without that circuit for now. Many of the online forums talk about the Power Converter outputting 0V when bad, but in my case its happily outputting 13.5V without a load ... that then drops to <4V under load.

Any insights or guidance greatly appreciated.
Mark

 

[John From Detroit]

Imply yes. Guarantee no.
WFCO's have a common failure mode or two and one of them is a fairly easily replaced part.. IF you know the value of the part that is.. Alas I do not.
If you decide to replace.. If the WFCO is power distribution panel and converter in one assembly consider teh Progressive Dynamics 4600 line (Match the last two digits to the WFCO close as possible)
If' it's a 'Stand alone" converter (not part of the fuse/breaker panel assembly) then the 9200 series.
Made in Marshall, Michigan.. You won't find a better converter.

 

[Contributor]

What happens with the battery charged up and connected and the power converter disconnected from the 120 VAC?

 

[mqshaw]

With the battery fully charged, and the breaker on the charge converter tripped, the lights are bright, the fridge works etc.

 

[mqshaw]

Imply yes. Guarantee no.
WFCO's have a common failure mode or two and one of them is a fairly easily replaced part.. IF you know the value of the part that is.. Alas I do not.
If you decide to replace.. If the WFCO is power distribution panel and converter in one assembly consider teh Progressive Dynamics 4600 line (Match the last two digits to the WFCO close as possible)
If' it's a 'Stand alone" converter (not part of the fuse/breaker panel assembly) then the 9200 series.
Made in Marshall, Michigan.. You won't find a better converter.

The panel is a WF-8955PEC, with the converter below the fuse panel (see picture)

 

[Contributor]

Check for tightness on all connections. But it seems like if the connections for the converter are tight (both (-) and (+), then it points to the converter.

 

[mqshaw]

Check for tightness on all connections. But it seems like if the connections for the converter are tight (both (-) and (+), then it points to the converter.

View attachment 156298

I checked the connections, they were all tight. So i pulled out the converter and took a look at the back off the board. Clearly shows signs of burn out on two of the 1.5K Ohm resistors.
Time for a new converter i believe.

 

[NY_Dutch]

The definitely looks like the "magic smoke" has escaped...

 

[Kirk]

I found that one of the lighting circuits appears to have a short to the trailer ground. But, even with this fuse removed, the cabin lights still glow dimly when running only on sure power.

There is something really strange about that and a short would not cause it. I would have to be there with my volt/ohm meter to even discuss it.

With the battery connected, power converter running

13.5V on the DC side of the power converter with no 12 appliances running12.9V on the DC side with appliances running.With the battery disconnected, power converter running
~13.1V on the DC side of the power converter with no 12 appliances running~3.8V on the DC side with appliances running.

Your voltages are a bit suspect. Was the last voltage 13.8V rather than the 3.8V that you wrote?

Unfortunately it did not go so well ... the battery died the second day, while connected to sure power at the campsite. I brought a battery charger with me, so was able to get the battery charged back up for the rest of the trip.

This would certainly seem to indicate that the converter has failed.

Time for a new converter i believe.

From what you say, I tend to agree. I am no fan of the WFCO products and the converter in our 2012 travel trailer failed a couple of years ago and I replaced the entire thing, with one from Progressive Dynamics. They make direct replacements for many of the WFCO products.

If you do this work yourself, be very careful, remove the shore power cord and lift the negative cable from your battery or batteries before you start. Make sure that you mark where each wire came from and be sure that it goes back to the proper place.

 

[mqshaw]

It was definitely in the 3.8V range, i tested it multiple times, with multiple appliances. The other day it was dropping down to 7 or 8V, but i didnt want to add that confusion to the thread. I think that it just needs to be replaced and the burn marks confirmed my suspicions.

I will look at the complete replacement as an option, thanks for the heads up.

 

[CharlesinGA]

The Progressive 4600 series is a replacement for the WFCO. It comes in a steel box designed for the Parallax panels, but if you read the instructions it will tell you to remove the screws retaining the converter in the steel box, and remove it and discard the steel box which seems like a waste. Progressive Dynamics does have part numbers for the converter without the housing, but price wise, its a wash.

Installation:
7. Attach new adapter bracket to power center using (2) screws removed in step #6. 8. Remove new converter core assembly from provided enclosure, by removing (4) screws securing converter to enclosure and slide converter out. Discard the metal enclosure and screws as they are not used when replacing this model converter.
9. Slide new converter into power center. Route black/white/green wire-set into AC power section and black/ white wire-pair into DC section. Secure converter by snapping into bracket installed in step #7......................................

PD4655V 55 Amp Converter Upgrade

The Progressive converter without the housing...................... (may be impossible to locate this...

PD4655WV

55 Amp Replacement Converter Section. With built in Charge Wizard.

WFCO™ #8955 only. Does not come with metal box.

Best Converter also carries the Boondocker line of products which is the Power Max line relabeled. They are China made but apparently fairly well designed.

BD 1255 MBA 55 Amp 4-Stage Main Board Replacement

 

[mqshaw]

So just to update everyone, i replaced the power converter and its working great. Thank you for all your helpful suggestions.

I went with the PowerMax PM4 55A converter, with minor modifications to the case it fit in nicely. https://amazon.com/dp/B01ER3LH1G