It seems to me that I always use 4.5V and it works the best for me. Anything higher and I tend to get dry hits, and anything lower doesn't seem to satisfy. The way I see it, we don't smoke "variable" analog cigarettes so is variable voltage really that necessary? What's wrong with just use one fixed(but powerful voltage like 4.5 or 4.8) and using a standard resistor (like 2.4 Ohms). It seems to me that this combination gives plenty and vapor and strength comparable with cigarettes. thanks