I really don't know if it's harmful to keep the batteries (I have 2) on the charger, probably not, but when I get home and plug in to shore power I turn off the batteries after a couple of days and turn them back on a couple of days before the next trip. I think if the charger is working properly it turns on and off as required.
Paul & Sheri - Upstate New York - SUN-0258
Amateur Radio KD2KCY - VHF 146.520 MHz
2012 F150 F/X 4, 6cyl EcoBoost, Max Tow pkg
2013 Rockwood 8280WS 5th wheel
2006 Sunline Solaris T-1950