I am interested in getting a chain-vape device and am looking at the 18650 mods, but really would prefer an auto battery. I caught Grimm Green's recent review of the upcoming Vapor4Life "Vapor Zeus" Cigar-like device but it's not on the market yet. (One of the devices was auto, the other was manual that could behave as an auto if you turned on that feature! Very cool!) Does anyone happen to know what the largest current batt device is that is still auto?