2 CR2's or 2 CR123's with diodes to reduce the voltage.
The GG, Prodigy and SD are ideal-sized devices.
they are not all the same size tho..
part of the design parameters behind the SD was to keep it as small as possible whilst at the same time contain an adequate sized battery..
in short a compromise between battery run time.. battery life time and ergonomics.. this was nine months ago... back then the SD was huge compared to the average sized e cig.. we did start a new thing..
thing have changed since.. apart from the janty stick the SD is the smallest of the currently available bigger battery devices..
folks now have a choice between several bigger battery devices..
we have three main differences.. the switch positioning.. the actual physical size (and weight) of the device.. and what is considered an ideal voltage to feed an atomizer..
some things are fixed.. longer run time means bigger battery and more weight.. nothing comes free..
its a big world and a big market for such devices.. we are now hitting nearly 1000 SD kits sold to over 34 different countries.. the lastest one being India..
people do like bigger battery devices.. but.. starting with the janty stick and ending with something that uses a much larger battery or too larger batteries leaves a big choice in between..
its easy to just think higher voltage means better vapour.. bigger battery means longer run time.... but there are other factors involved..
we thought about producing an SD variant built around an 18650 2600 mah battery long ago but didnt because we thought the end result would be too large and heavy for everyday usage..
here is pic just to give folks an idea of what battery cells could be used to produce an e smoking device..
the bigger the battery the longer the run time.. but where exactly is the line drawn.. ??
this is purely a theoretical discussion.. no what is the best product stuff.. but some things are missing from the average comments..
trog
ps... the 2 on the far left are janty stick ones.. the purple one with the spider on is an SD sized one.. the third from the right is an 18650 one..
two SD sized ones in series are roughly the same size as one 18650.. but whilst having a higher voltage would only have around 25% of the run time..
the little silver one in the middle is a 901 mini sized one.. the capacity which equals run time with the batteries on show is from around 130 mah to over 6000 mah..