you are definitely flirting with 12VDC appliance failures operating them on 16.5VDC...
Sounds like you may have blown a couple of items already from your post...
These OLDER CONVERTERs were designed to use the battery as a regulator in the output circuits.
There are alot of the 12VDC operating items in your setup. Here is a typical 30A Power Distribution diagram showing what is connected to the 120V and 12VDC Power distribution panels for a typical trailer setup...
Note both your on-board Converter and the Battery Bank feed the 12VDC Distribution panel. It is this way so that the trailer can be used with both 120VAC Shore Power as well as camping off the power grid for the most necessary items in your trailer.
It could get pretty expensive replacing all of those 12VDC appliances and control boards...
Just saying...
Roy Ken
