I have a 2001 Fleetwood Class A. I recently, within the past 2 months, put in new batteries for the engine and the coach. They all are now dead. I have been using AC so there has been no draw on them....
Also check to see if they were installed correctly...If installed in REVERSE you may have blown the REVERSE POLARITY fuses in the 12VDc Power Distribution Panel.
Bad news is if the batteries have been setting in a full discharge mode for any length of time chances are irreversible damage may have been been done to the batteries. Use a multimeter to read the battery DC voltage at the terminals...