I tried a test for that, but used "13.7" since that is what the batteries are at and full. If I jack up the voltage to 14.x, it will be forever till things settle and I could take readings.
RV sitting in yard plugged in at 13.7 with battery bank 450AH of AGMs full. Disconnected solar and all possible 12v loads. Disconnected 55 amp ADJ neg wire at charger's terminal.
So PowerMax 55 ADJ still plugged in but not connected to load, reading 13.68 on multi-meter at DC terminals and 13.7 on its own little meter. (Going back and forth 13.67/68 but got it to stay at 13.68--very sensitive knob, hard to get it to stay at any one second decimal place)
Trimetric says disconnected batteries are at 13.7 and have a draw of 00.2 amps (some of which would be the Trimetric itself)
Stuck the neg wire back into the converter's terminal. Trimetric says battery voltage still 13.7 but charging at 1.0 amps, tapering.
Voltage at converter terminals 13.68 and at the battery bank 13.66 (wiring zoo between converter and battery bank)
Waited till amps tapered to 00.1 on Trimetric. Voltage at converter terminals still 13.68, batteries back to being full at "13.7"