On drop-ins looking here:
http://www.bestconverter.com/AGM-and-Lithium-Deep-Cycle-Batteries_c_283.htmlSee the UB12100 110AH AGM for $210, at $1.9/AH and the
Espion360 120AH Li for $1,340 at $11.17/AH
So 11.17/1.9 = 5.88 times, not 4 times more per AH. But the point is usable AH.
True about usable AH that there is more with Li, but how much more? There is a debate on what the range is for Li to do say 20-80s or to do 20-100s or whatever. A 20-80 is 60%. You can do 40-100s with AGMs.
Number of cycles at a chosen SOC range might be a better way to compare them for intended use, haven't got into that.
Noted about weights and how often needed to go to lower SOC down South in winter, and resulting gen times as a factor.
More people with stakes in Li for RVs should provide their thoughts as an aid to others who are considering Li.......