Charging a Battery Bank

Just a quick update on my WFCO 8955. The converter/charger is ok. I wanted to test voltage at the unit since my previous test at the end of the battery cables showed I wasn't getting anything. I pulled the unit out from under by refrigerator, where the dealer installed it and found the positive cable going to the battery wasn't connected. Once I put that back on, everything is working fine now. Of course I still wouldn't get the 14.4 like everyone else reports they don't get but at least I have a functioning unit. While I was doing the test, I started thinking about if I buy the Duracell 6v AGM GC2 batteries the WFCO unit can't even be used properly as a way to keep things charged between camping trips because it has no temperature control. Since the Duracell literature states TC must be used when charging their batteries, why are they even sold for RV use? I have to assume that the vast majority of campers that have them installed do not have a temperature control converter/charger installed in their campers. They might have a portable charger they use with their generator that has TC but who leaves those attached between camping trips?