This is being discussed on another thread right now.
Block diagram in "12 Volt Side of Life" shows battery wired between converter and fuse block, meaning no 12VDC w/o battery in place -- Opinions differ as to whether diagram is in error (doubt it or maintainer would have corrected by now) or battery is serving as a filter for the converter output.
The latter would explain why older rigs with cheap, transformer converters may be wired that way and newer rigs with theoretically better electronic converters are not.
Both my '83 Jayco 16' and my '91 Scamp
13' had the older converters, but I don't recall ever trying to run either with no battery.
On the Jayco, the 120VAC shore cable came in to a small, standard breaker box w/two 15A breakers -- One was for the rooftop a/c and the other powered typical duplex outlets -- The converter was plugged into an outlet, as was my fridge
, and its 12VDC output was eventually connected to an external fuse block w/glass fuses. I don't recall exactly how the battery fit in. Removing the converter was easy because all I had to do was unplug it and leave the fuse block in place.
On the Scamp
, again the 120VAC shore cable went to a breaker box w/two 15A breakers. One breaker was reserved for a/c, the other powered duplex outlets The converter was again plugged into an outlet for its 120VAC power, but the manf had included the 12VDC fuse block inside it, using blade fuses.
Currently, the converters now include the 120VAC breakers and the 12VAC fuse block and the 120VAC shore cable goes directly into it. This simplifies the wiring for the trailer manf but complicates the record keeping a small bit. I don't know where the battery is in one of these arrangements.