we do make sure when we leave home that we have fully charged RV batteries .
mostly by plugging the TT in to 120V for the day prior while packing .
when we return to home we plug the TT into 120V again .
when we park the trailer for storage I fully disconnect the RV batteries from the TT system . I do make sure they are fully charged .
i have installed AGM batteries Exide EDGE in my pickup .
the trailer batts are the standard 12 volt tandems .
i am waiting to see a deal on AGM batteries on a true DEEP CYCLE RV battery .
I would rather spend the money on good Exide Edge AGM batteries for my pickup that i drive most days than on an expensive solar panel for my trailer which sits 333 days each year .
we camp without hookups 70 % of the time
we have no solar .
we have no generator.
we park our trailer .
we turn our diesel pickup around .
we use HEAVY DUTY 12 foot jumper cables to connect all 4 batteries together to run the 12V in the trailer .
the duramax gets driven every 2nd or 3rd day .
its batteries get fully recharged .
as soon as we return we hook up the jumpers again .
the 4 batteries basically equalize .
we camp maximum 9 days in a row utilizing this method .
been doing this for 15 years .
an upgrade in batteries will be efficient enough .
2 big golf cart GC2 batts for the RV and AGM batteries for the tow vehicle. or 2 group 27 RV deep cycle batteries . AGM if you can find them .