Converter Problems

[buzzards27]

I think I have a bad converter/board and I was hoping someone could walk me through the troubleshooting.

I had low batteries condition this spring and recharged them a while ago. Yesterday while sanitizing and charging the up the fresh water system I used the water pump quite a bit and find that the batteries are again low. (It is raining and I cannot get accurate readings at the moment).

I have a WF-8955 55 Amp Power Center from 2004 http://www.wfcoelectronics.com/index...d=46&Itemid=77
with this board 8955MBA Main Board Assembly For 8955 ANP or PEC.

With 120VAC connected and the batteries isolated I have no low voltage at any point inside, no lights. (the LP detector is wired direct to batteries and is providing a low voltage chirp) The converter doesn't appear to have any low voltage output. the fan isn't spinning. The 40AMP fuses on the board at the battery input are good.

The first step in the manual asks me to test the VDC of the converter output at the battery end of the cables with them disconnected from the batteries. I will take a reading as soon as I get a window of no rain, June or July, maybe....

http://www.wfcoelectronics.com/docum...%20English.pdf


Looking back on our usage so far, we haven't used the 12V system that much, water was to city systems, shore line used everywhere and heat and lighting was almost all 120V. Could we really have been using the batteries exclusively for the last 6 months for about 25 days of limited 12V usage?

Any suggestions or advice?

[Herk7769]

Originally Posted by buzzards27

I have a WF-8955 55 Amp Power Center from 2004 WFCO - New world of power ideas - WF-8955 55 Amp Power Center
with this board 8955MBA Main Board Assembly For 8955 ANP or PEC.

The first step in the manual asks me to test the VDC of the converter output at the battery end of the cables with them disconnected from the batteries. I will take a reading as soon as I get a window of no rain, June or July, maybe....

http://www.wfcoelectronics.com/docum...%20English.pdf


Could we really have been using the batteries exclusively for the last 6 months for about 25 days of limited 12V usage?

Second question first: No. The failure if there is one has to be rescent. As stated in previous posts, internal resistance and Propane dectector parasite load will kill your batteries in 1 to 2 weeks of "no load" (ie you not "using" anything).

First Question second:
The trouble shooting guide is right on. ** my notes

If the converter output voltage at the battery reads in the 0.0 Vdc range,
or the battery is not charging, check for:
- an open inline fuse in the battery wire (if installed by OEM)

** Look for this within 18 inches of the battery. (It may be a red covered auto resetting current limiter - also look for loose or corroded terminals)

- an open wire between the converter and the RV battery

** test for 13 volts BEFORE and AFTER the red covered current limiter.

- loose ground connection

** Black wire to frame.

- improper torques

** Loose wires anywhere

If the converter fuses and AC voltage are good, but the converter output still reads zero volts, the converter is not functioning properly.

Contact Cheng USA, Inc. Tech Support at 1 (877) 294-8997.

[buzzards27]

thanks lou, on the in-line fuse. if I am seeing power FROM the batteries at the converter terminals would that suggest an in-line fuse is not the problem? Would an in-line fuse kill the cabin's draw from the batteries?

I am not trusting my old volt meter at the moment, I might have damaged it earlier in this darn rain, so readings are going to have to wait a bit to take a reading at the battery end of the cables.

The lights do work (lum maybe 60%) with the batteries connected. but with the batteries disconnected I am getting a converter output reading (at the "TO batteries" terminals) of about 6 VDC with this questionable meter, but there is no low voltage activity (no lights), but the LP detector does chirp when i flip a light switch. I would think the converter would power at least one light... I have yet to see or hear the converter fan run.

I would think this 6VDC reading should be comparable to the reading I would get at the other end of the cables at the batteries...

Thanks so far, I'm heading out for a new meter and I'll check the "Step One" reading the next break in the rain. I have the batteries on a slow charge and will post a reading soon.

Originally Posted by herk7769

Second question first: No. The failure if there is one has to be recent. As stated in previous posts, internal resistance and Propane dectector parasite load will kill your batteries in 1 to 2 weeks of "no load" (ie you not "using" anything).

If this converter is due for replacement, I figure I can DYI. I'm wondering on replacement opinions. Do I go OEM like the one I found online or are there better 3 stage charger options that would either fit this case or nearby? I have a enclosure next door big enough at the water heater I could use.

First Question second:
The trouble shooting guide is right on. ** my notes

If the converter output voltage at the battery reads in the 0.0 Vdc range,
or the battery is not charging, check for:
- an open inline fuse in the battery wire (if installed by OEM)

** Look for this within 18 inches of the battery. (It may be a red covered auto resetting current limiter - also look for loose or corroded terminals)

- an open wire between the converter and the RV battery

** test for 13 volts BEFORE and AFTER the red covered current limiter.

- loose ground connection

** Black wire to frame.

- improper torques

** Loose wires anywhere

If the converter fuses and AC voltage are good, but the converter output still reads zero volts, the converter is not functioning properly.

Contact Cheng USA, Inc. Tech Support at 1 (877) 294-8997.

[Herk7769]

Would an in-line fuse kill the cabin's draw from the batteries?

If that current limiter was bad, no voltage from the batteries would pass it.

Ok, I think I know what is wrong. Whether it can be repaired or not is another question.

I believe 1/2 of your full wave bridge rectifier is bad. This only takes 1 diode to fail "open" If I recall my college physics correctly, if 1/2 of the bridge is out you will only get half wave recitfication.

It will still be 12 volts out but only 1/2 the time (1 12 volt cycle every 1/30 of a second followed by 1/30th of a second of nothing). A DC meter in this case would read about 6 volts steady state due to the ripple removing "smoothing" capacitors.

Full Wave Rectifier and Bridge Rectifier

[donn]

there is no real way to test converters at home. Take it out and take it to a repair shop for proper testing.

[Herk7769]

Originally Posted by donn

there is no real way to test converters at home. Take it out and take it to a repair shop for proper testing.

I think I mentioned that in an earlier post.

[buzzards27]

LOL, I would have never imagined such a thing, you are such a great asset to all of us.

Ok, I got a meter and we do have 8.4 VDC at the terminal outlet and 8.3 or 8.4 VDC at the ends of the battery cable. all without the batteries connected.

still no noticable low voltage activity, but there is 8.4 VDC across one of the low voltage branch currents that i did test. If needed, the meter I have can test up to 10 ADC for a short duration.

Seeing I should have a reading in the 13.6VDC range we have a problem, but one half of 13.6 does not equal 8.4. does the diode issue you suggest still apply? if so, does this mean I replace the converter or is it more extensive?

if it is the converter, what are my options?

Originally Posted by herk7769

Would an in-line fuse kill the cabin's draw from the batteries?

If that current limiter was bad, no voltage from the batteries would pass it.

Ok, I think I know what is wrong. Whether it can be repaired or not is another question.

I believe 1/2 of your full wave bridge rectifier is bad. This only takes 1 diode to fail "open" If I recall my college physics correctly, if 1/2 of the bridge is out you will only get half wave recitfication.

It will still be 12 volts out but only 1/2 the time (1 12 volt cycle every 1/30 of a second followed by 1/30th of a second of nothing). A DC meter in this case would read about 6 volts steady state due to the ripple removing "smoothing" capacitors.

Full Wave Rectifier and Bridge Rectifier

[buzzards27]

Just talked with John, Tech Support, at Cheng USA, Inc. He gave me an alternative method to test the converter. Remove the two 40A on board fuses and test across the Neg and VCC terminals on the 12VDC board. With no load we got a 13.67VDC reading so the converter itself is good. He then had me test with the 40A fuses back in. He said that if that reading was in the area of 8 to 10 VDC the converter board was bad. Apparently the board is bad. 8.4VDC again.

If I understand him correctly he says the converter is providing the proper voltage but not the proper amperage. He recommended a new converter from Best or American RV. others may not be warranted.

Any suggestions or advice?

[Herk7769]

Originally Posted by buzzards27

Just talked with John, Tech Support, at Cheng USA, Inc. He gave me an alternative method to test the converter. Remove the two 40A on board fuses and test across the Neg and VCC terminals on the 12VDC board. With no load we got a 13.67VDC reading so the converter itself is good. He then had me test with the 40A fuses back in. He said that if that reading was in the area of 8 to 10 VDC the converter board was bad. Apparently the board is bad. 8.4VDC again.

If I understand him correctly he says the converter is providing the proper voltage but not the proper amperage. He recommended a new converter from Best or American RV. others may not be warranted.

Any suggestions or advice?

The Full wave bridge I mentioned is in the DC board. Thanks for the additional troubleshooting step. I made a note of it in my Camper 3 ring binder of "stuff I need to know while on the road." In my case, my luck is so bad I would not have internet access when something broke.

I have no experience with either company only WFCO.

[buzzards27]

Lou, do you figure, based on what you hear, that I should just change out the converter? One last thought could a short in one of the low voltage circuits create the same type of voltage drop?

Right now I am considering letting the thing "trickle charge" the batteries like it must have been doing and just recharge them before and after each trip.

I could also get a small three stage charger and carry it with us on trip. I mean a 55amp charger would do the same thing for much less.

Thanks again

[Herk7769]

I am having a hard time with this one. My "pilot" is kicking in. While it would be certainly cheaper to ignore the problem and use a dedicated charger to top off your battery; I am concerned about "unintended consequences."

1) You already have a failed board in a component that handles ALL the power in your rig, AC and DC. There is no way of knowing if that is the only component that will fail on that board. The next one could be catastrophic in its consequences. (like a fire)

2) It goes against the grain to "fly an aircraft" with a known electrical malfunction. (see above)

If it was my camper, I would buy the best possible replacement that I could. The WFCO unit is not a "bad" unit and I would have no issue with repairing it or replacing it with an identical unit. But since I would NEED to do something to fix the problem; and I have time to do so; I would see if there is a better unit that would suit my needs. What that unit might be I have no idea and would have to research it.

[showtime0022]

Dont remember if I tighten the Jesus nut ! Lol .... Lou knows what im talking about. Everyone else its a giant size nut on top of the rotors. If that nut comes off. Guess who youll be seeing. Sorry about the aviation joke.

[buzzards27]

i'm sure I will get the replacement soon enough, that was the first option I had listed. At least it isn't keeping me up all night worrying about it if I use it as is over the next few weeks as long as I watch the batteries closely. I'm just glad I know what the problem is now. If you remember we had another thread this spring where I was dealing with weak batteries coming out of winter storage. I did suspect the converter had issues back then. Now it all that makes sense.

Regardless, a good "travel" charger is my next purchase. Hopefully one that can tend and well as boost when needed.

Thanks again.

Originally Posted by herk7769

I am having a hard time with this one. My "pilot" is kicking in. While it would be certainly cheaper to ignore the problem and use a dedicated charger to top off your battery; I am concerned about "unintended consequences."

1) You already have a failed board in a component that handles ALL the power in your rig, AC and DC. There is no way of knowing if that is the only component that will fail on that board. The next one could be catastrophic in its consequences. (like a fire)

2) It goes against the grain to "fly an aircraft" with a known electrical malfunction. (see above)

If it was my camper, I would buy the best possible replacement that I could. The WFCO unit is not a "bad" unit and I would have no issue with repairing it or replacing it with an identical unit. But since I would NEED to do something to fix the problem; and I have time to do so; I would see if there is a better unit that would suit my needs. What that unit might be I have no idea and would have to research it.

[kbrown1075]

Very good thread!!!!

[buzzards27]

Originally Posted by herk7769

I am having a hard time with this one. My "pilot" is kicking in. While it would be certainly cheaper to ignore the problem and use a dedicated charger to top off your battery; I am concerned about "unintended consequences."

1) You already have a failed board in a component that handles ALL the power in your rig, AC and DC. There is no way of knowing if that is the only component that will fail on that board. The next one could be catastrophic in its consequences. (like a fire)

2) It goes against the grain to "fly an aircraft" with a known electrical malfunction. (see above)

If it was my camper, I would buy the best possible replacement that I could. The WFCO unit is not a "bad" unit and I would have no issue with repairing it or replacing it with an identical unit. But since I would NEED to do something to fix the problem; and I have time to do so; I would see if there is a better unit that would suit my needs. What that unit might be I have no idea and would have to research it.

I am about to change out the power center today and the why the converter blew out is still bothering me. There is a transfer switch so I doubt the prior owner did it by running the genset while on shore power, so why did it blew out? Could the transfer switch be bad? How would I test the transfer switch before I hook up the new converter?

[Herk7769]

Need to bump that question to someone who knows a lot more about MH systems than me. (5th wheel guy)

[buzzards27]

Originally Posted by buzzards27

I am about to change out the power center today and the why the converter blew out is still bothering me. There is a transfer switch so I doubt the prior owner did it by running the genset while on shore power, so why did it blew out? Could the transfer switch be bad? How would I test the transfer switch before I hook up the new converter?

Got the new power center in today along with a battery cut off switch. Before I power it up I would like to test the transfer switch, I suppose I can just test the AC voltage as I power up between the genset and the shoreline. I guess a voltage spike wilt mean there is a problem with the switch.

[buzzards27]

Testing is done and so far the new converter is working as expected. With the battery kill switch next to the power center it was easy to watch the converter kick in as I shut down power from the battery.

Thanks to everyone, especially Lou, for all the advice and handholding. Could not have done it without you.

[buzzards27]

Well, I am a little bummed out, we still have a problem somewhere. Shut down the shoreline before going out to diner and came back four hours later to dead batteries. Not sure if the batteries had a full charge or if there us a low voltage short somewhere. I pulled all the 12VDC fuses and I am charging up the batteries for the next day or so to make sure we have a full charge and then I'll start checking each circuit.

I do not have an an ampmeter, so I am going to look at each circuit for a rapid voltage drop.

Any advice is welcome.

[Herk7769]

Is there a light or lights on somewhere? Like in the storage lockers?
Something is putting a draw on that battery for sure.