I've looked into the 60ah to 94 ah battery swap. At this time it seems to be more trouble, cost, and down time than I would like. There are frugal leaf owners that have added a second leaf pack to regain a reasonable range. They wire the second pack in to the cables between the main battery and the "electrical machine." I don't want that much weight added to my 2014 bev I'm looking to build a smaller, lighter, denser, simpler, 96 cell battery that will just give me an extra 20 miles. I figure the guess o meter and state of charge will not be accurate, but I am ok with that. Is the state of charge determined by amp flow? and if so, where is it measuring that? Is it measuring voltage to determine state of charge?