There are several types of converters. Most older converters and many OEM converters output a single voltage in the 13.6v range. Modern converters are usually 3 stage and the voltage output depends on the battery charge state. The output voltage when the battery is discharged is in the 14.4 to 14.8v range and the voltage drops to about 13.2 when fully charged.
For a quick check without using a voltmeter, unplug the RV and turn on a few lights. Then plug in the RV and see if the lights get brighter. You will probably need someone else to plug in the RV while you watch the lights.
Class C, 2004/5 Four Winds Dutchman Express 28A, Chevy chassis
2010 Subaru Impreza Sedan
Camped in 45 states, 7 Provinces and 1 Territory