? electrical problem...what’s happening? Should I worry?

Had a similar problem last fall and this spring,lights kept dimming.
Converter finally died and after I put a new one in no more problem.

Converter output seems to be working. Now test at 12 volt DC battery connection, then go immediately to the battery and check voltage on battery. Readings should be nearly the same allowing for slight voltage drop. Maybe .1-.2 volts

Take the voltmeter with you on the trip. If you have a portable battery charger, take that too.

Your converter does seem to be working more or less properly, at least at the moment. About the only other easy check would be to turn off the AC power and see how it reacts to loading only on battery power (no need to run the battery down too much--just see if the battery voltage and brightness both stay in the reasonable range as you turn on more lights, etc).

You may very well have had a loose/poor connection at the battery that happened to get corrected in the process of checking things out.

Update: I had the battery load tested; was assured that the battery is ok. So, I hauled the trailer home, have hooked it up to 30amp shore power in the yard. I decided to try a “lazy-man’s” approach before removing the panels to the electrical board and converter and learning how to test the converter (but thanks to enblethen for the link to the schematics if I later have to do this). Checking the starting voltage on the battery was above 13 volts, inside the trailer I heard the converter humming along at the beginning, so presumably it is charging or trying to charge. So, I have turned on every light in the trailer. At about 12 hours the voltage at the battery was 12.76, this am at 24 hours it’s 13.64 (and the lights are continuing to shine brightly)....am I correct. in concluding that the converter and system is intact? I am not hanging out in the trailer so don’t know if there has been any temporary dimming of the lights like I described in the original post. Maybe the reason for the original dimming which prompted this search will forever remain a mystery and hopefully not recur? If any readers think I should pursue this further I would welcome their advice since, after all, I am attempting to be proactive rather than have a problem on the upcoming trip. Thank you.

OPs converter is now 55 amp. I would not go any less.

Battery holding 12.56 disconnected in storage does not seem bad. A few lights running the voltage to 12.3 seems normal enough.

Need to plug the WFCO in and see if you get 13.6+ volts out of it.

I recommend a Powermax if the WFCO needs replacement.

https://powermaxconverters.com/product/pm3-mba/
The 35 amp is fine.

kabbro wrote:

enblethen wrote:
Fairly late model converter with three stage output.Owner's manual
Some troubleshooting system on page 7.
Sounds like bad battery!

Enblethen (and everybody else): Thank you. I will take the battery to a shop and have it tested, and am perfectly willing to have the battery replaced as that would be the least expensive option—but I am thinking that a starting reading if 12.56 volts and ending reading of 12.6 after 48 minutes of ldrawing lighting etc is not too bad...what say those who are more knowledgeable than me? Thanks!

c
Correction: ending voltage was 12.3 volts

enblethen wrote:
Fairly late model converter with three stage output.Owner's manual
Some troubleshooting system on page 7.
Sounds like bad battery!

Enblethen (and everybody else): Thank you. I will take the battery to a shop and have it tested, and am perfectly willing to have the battery replaced as that would be the least expensive option—but I am thinking that a starting reading if 12.56 volts and ending reading of 12.6 after 48 minutes of ldrawing lighting etc is not too bad...what say those who are more knowledgeable than me? Thanks!

Fairly late model converter with three stage output.Owner's manual
Some troubleshooting system on page 7.
Sounds like bad battery!