Ellpea , I have been watching this thread, and others you have been involved in, and I have come to one conclusion.
It is not an insult to say that you do not know your trailer - it is something new to you and I can assure you that if I somehow became the owner of a Cessna Piper Cub, then I would be just as unfamiliar with the plane.
But the good news is that camping trailers are all more alike than different, just as small planes share many common features. Therefore, if I woke up tomorrow with good title
to that Cessna, I would go to the local airport and find an owner (or three) of similar planes to walk me through the basic construction and operation (as a first step toward getting my pilot’s license).
I strongly suspect that your trailer does
have a converter and it would charge the trailer’s battery if it was operating properly. But only an onsite inspection can confirm that. My best guess is that you have a converter that is not fully functional, but that is only a guess. And that’s the rub, dealing with this issue in the forum, with limited information and no actual inspection, means that we can only take uneducated guesses.
The power systems in most trailers are not that different, although larger campers and motor homes have more stuff. If I could get a look in your trailer, I am sure I could help you figure it all out, and I am not even one of the more knowledgeable trailer owners.
So my suggestion is to network with one or more local camping trailer owners and have them over for a glass of wine, a pizza or similar enticement, and start a conversation about the trailer sitting in your driveway (after it gets back of course). There is no substitute for someone who knows just a little more than you taking a look at the actual hardware.
Best of luck and if you ever get this way I will be glad to have a look at your rig and offer my mostly uneducated two cents.