Yes, it makes sense, since your DVM is reading the (huge sink) battery voltage.
Remember there is a slight line loss between the converter and the battery.
So, as long as you can measure 13.5-14.1 VDC at the battery after the RV has sat plugged in or on the generator for several hours, be comfortable with the fact that the charger is working.
Much higher? Overcharging! Charger is defective.
Much lower? faulty charger, no power to charger, etc.
Other than that, replace the battery every 5 years. Or sooner if you take it down too low too many times.
TT 2015 19RD "TheJayco"
TV 2003 F-350 "Montblanc" - Housebroken chore truck
Sitting in The Cheap Seats.
And proud of it!