Before you spend the $$ on lithium, take a look at carbon foam batteries by
Firefly. These have many of the advantages of lithium but cost significantly less, and the control system required to charge and maintain them is considerably cheaper and less complicated (similar to AGM). The main advantages of lithium over carbon foam are weight and recharge speed - both of modest value in an RV. The Firefly have been tested by several independent boating publications and seem to live up to the manufacturer's claims. I have several friends who have put them in boats in lieu of lithiums and are happy with them so far.
