Need your advice. House batteries not charging on shore power or generator

[UtahRv]

Hello everyone, I'm new to this, and looking for some advice. I've been searching the forums for an answer, and haven't found one. My house batteries in my MH are definitely not charging on generator (or shore power) but they are charging on the alternator. We found this out the hard way on a camping trip this weekend. The generator and shore power are producing 110v on the ac side and are powering the 12v side (lights, furnace blower etc) properly. The batteries seem ok. I had charged them out of the coach separately on a regular plug in automotive charger when I was getting the coach out of winter storage. I also had them load tested at autozone (separately out of the coach) and they tested good. I also used each of them to start the motor in the MH while we were camping as part of my boondock troubleshooting since I didn't have a meter with me. Both batts have proper amount of water. I spent several hours trying to trace the wiring and voltages once we were back home. Here is my setup...

2013 Thor freedom Elite

WFCO 8955PEC converter

2 12v deep cycle batteries in parallel for the house

1 12v for the chassis battery

• House batteries read empty on the panel, but are reading 12.63V with my handheld multimeter

• (as part of my field troubleshooting this weekend I even hooked my starting battery up to the house leads with jumper cables and the panes still read empty for the battery. I didn't have a meter)

• No change in voltage at the battery posts on generator or shore power, but the lights get brighter, and everything 12v works fine

• 13.6v at the house battery posts when the MH Engine is running at idle

• Checked all fuses and breakers at the power converter. All good

• Battery Disconnect Switch is connected


troubleshooting steps I took on the converter

• Without shore power, reading 11.7v at the positive lug and the "+VCC" lug on the fuse block even though batteries read 12.63v

• Took the same readings with a jumper cable going to the negative post on the house battery for my meter and got the same results, so it doesn't look like a bad ground

• On shore power, both +VCC and Pos lugs read 13.62v, but I still get 12.63 at the battery lugs

• Removed positive cable from battery, reads 13.62 but goes right back to 12.63 when hooked back to battery.

• I checked both sides of the disconnect relay. I get 13.62 on the converter side and 12.63 on the battery side when it is in disconnect, and the same readings for both sides when it is in connect mode (I can't remember now what the reading was, but I remember it was the same on both sides, which is what I would expect for proper function)


I don't get how the converter can produce what seems like the proper voltage, but not push it to the battery. Is it just not producing amps? I'm stumped. Is this a bad convertor? Seems like a pretty fast failure. We did buy this MH last year out of the rental fleet, but it only had 35k miles and it was a year old. I also don't get how the fuse block only seems to be getting 11.7v when I know the batteries are putting out 12.63. Is there something on the fuse block circuit board that can go bad? Is it possible that bad batteries could cause these symptoms? The only thing I can think is I need to get a new converter, as I have not seen ANY positive posts in the forums about the WFCO converter I have, but I would rather know that it is the culprit before I spend a few hundred bucks on a new one. I've just run out of ideas on what else I can test. If nothing else, I understand my coach's electric system much better now! Any ideas would be appreciated!

[Skip426]

Sorry you're here with problems , and I'll re-read your post several times , to see if I can come up with questions or ideas, that may help.


I'm thinking you have a bad connection somewhere , that like you say , passes volts that show on the meter but not amps to charge the battery. I'll ponder this problem for a while and try to get back, with ideas, after I've finished dinner.

[UtahRv]

Thanks! I did check and tighten every connection I could find, but there could be a hidden one. I honestly don't know if this ever worked. We hadn't dry camped for more than a day without driving until now.

[Todd157k]

if you take BOTH + battery cable off, and read a charging voltage (above 13v when plugged into shore pwr) on the cable, your converter is good. If the voltage drops when you connect them back, it should be charging. If not, your battery(s) are shorted inside.
You can also use your meter set on 10 Amps (or more) scale and hook the red to the battery, black to the cable. See if there's a current draw, and how much. Shouldn't be more than 4-5 amps and should reduce after a few hours. If not, your battery is shorted.
Work with one battery at a time. Disconnect the linking cable.

[UtahRv]

Thanks for the reply. I am reading the charging voltage when battery is disconnected. I hadn't read the amp draw there so I'll try that. I have my rig back in storage so it'll have to wait for now.

Thanks again!

[Skip426]

I found your Converter on line , and think it is the same as one I helped a neighbor replace, for a no charge condition.
There were two , transformer coils on the internal circuit board, one was burnt out, and the smell was horrible. I can't say if there was any output from the remaining coil, he had done the testing and ordered the replacement , but if you can smell a foul odor from your unit chances are it's shot.


EDIT: A question , does you converter have a pair of , reverse battery polarity protection fuses, on the circuit board, are they both good?

[UtahRv]

I had the converter out, and I didn't notice a burnt electronic smell, but I'll check again. It does have the reverse polarity fuses. Both are good.

Thanks!

[Skip426]

Originally Posted by UtahRv

I had the converter out, and I didn't notice a burnt electronic smell, but I'll check again. It does have the reverse polarity fuses. Both are good.

Thanks!

Sorry I should have re-read your original post, where you said +VCC and POS+ volts were the same , that indicated that the reverse polarity fuses were good.

BTW; in case anyone should ask +VCC , means the Positive Volts Converter Charger.

[UtahRv]

Checked the amp draw. I get nearly nothing (0.12) from the converter line when on shore power but I get a little less than 5 amps on the line from the chassis with the engine running.

[Skip426]

If by " amp draw" you mean you checked the wire, to the battery for power flow, and got those low readings.
I'm thinking you must have a very bad wire between the converter and the battery. High resistance in the wiring , could be tricking the converter into thinking the battery is fully charged, and causing it to cut back to , the float output.
Can you get a length of known good wire, I've used a 120v extension cord for this , disconnect the battery positive cable , attach the wire to the cable end , then roll it out back to the converter terminal , then using your , ohm setting check for zero or next to zero ohms , in the wire loop you've created.
Or you could take a 12v. battery and place it next to the converter and attach jumper cables , to see if the converter will charge the battery when it is right beside it, by-passing all the coach wiring.


EDIT: If we don't get this figured out soon, I'm going to have to detour on my trip south in the fall ,to look at this in person, it's got me perplexed.

[UtahRv]

You nailed it Skip. I got 5 ohms resistance I. The loop, so it jumped the battery straight to the converter with some jumper cables and everything was fine. I started taking measurements so I could install a new cable, and the measurements from underneath the rig weren't matching up to what I measured up top. Turns out the cable wasn't dropping through the floor near the converter like it looked. After taking all of my kitchen drawers out guess what I found. An auto resetting breaker in the circuit with BOTH lugs completely loose! Few turns of the wrench and I'm back in business. Many thanks, Skip. I'm just glad I kept chasing it and didn't end up replacing a perfectly good converter and batteries!

[Skip426]

Typical , weeks of chasing around and it turns out to be a 5min. fix.
Sorry I didn't think of the ohm check sooner, .
Anyhow , we both learned something, NOW , just need to remember it for next time.