I have been trying to do the research on my own and I have not been able to come up with a satisfactory answer to this question. I am guessing it might have to do with the configuration, but perhaps not. I am wondering why people are not using the coin/button type batteries in mods. I have looked at the mah and there are several lithium options with a higher mah. Can they not be stacked to give a higher voltage? They are tiny (even the larger ones) and could be used in the smallest mods. The batteries are so cheap and readily available. I am sure it has been experimented with, I am just wondering what the conclusions have been and why they have not been more widely used.