Ben, I have a Xantrex battery monitor and it shows .1amp draw when the batteries are disconnected. I know that there are 2 extra positive cables on the coach batteries and are not disconnected. At .1amp per hour, that's 2.4 amps per day or 12 amps in 5 days.
Also, your batteries may have sulfation and statification and can't be fully charged. Can you remove them to a garage and test with a hydrometer? I have mentioned before that I had the same issue with my old Winnebago with 10 month old batteries. Had to undergo massive desulfation and equalization to get them back. According to the battery manufacturers, you need 14.8 daily to recharge. http://www.exide.com/Media/files/Dow...0%205_9_13.pdf
The Intelli-power converter charger only produces 14.4v max and only for 3 hours on boost. This is probably done to prevent boiling and having to add water all the time.
I read on the forum that FR uses Exide batteries but unbranded, not Interstate.
Last, batteries lose the amp capacity as the temperature drops.