Older RV's often had a Magnetek 6300 converter, Modern ones often have a Parallex 7300 which is much better but still not up to my minimum standard.
The 6300, was well known as a battery boiler.. It had two issues that made it a poor choice, One, it only put a few amps to the battery for charging so re-chargind off a generator running it from say 8am to 8pm, NOT going to get the job done.
Second, if you plugged in for long enough to get the battery back to FULL, that dang thing did no know when to stop, So it kept on charging (overcharging) and could boil batteries (once charged) dry in 1-3 weeks.
The 7300, has better regulation but it still has no "Smarts" it puts out the same voltage all the time,, Hopefully not enough to boil 'em dry, but if it's nto enough to boil 'em dry,, It's not enough to fully charge 'em either.
Now, some modern RV's come with better 3-stage converters, IOTA, WFFCO and my favorite Progressive Dynamics with CHARGE WIZARD (Either optional and installed or built in).
These you can safely leave plugged in full time.