SO then I need just one 18650 to run it? Buy two and charge one while running the other?
Yes, every day swap em out...I hammer the hell out of my Vamo, go thru 2-2.5ml
Vivi nova mini tanks (clones from FT) with my favorite flavors, end of the day I would be at 3.7vdc (well above the Low V shutoff) pop out old battery, put in fresh charged battery for the next day, just rotate em out) [not draining Li Ion all the way to the "safety low voltage shutoff increases recharge cycle longevity a bunch]
By far my favorite tank on the Vamo has been the
protank 2 mini clone from FT , on the coils I pop the chimney off, pull the flavor wicks, rip off the end of a q-tip, fluff it up so there aren't any bumps in it, then twist a very thin chunk of cotton (it has to be thin or it unwinds gets puffy and starts gurgling), lay it across the coil channel, put back on the chimney and rubber piece, then using fingernail clippers nip off the extra wick...flavor and vape is INCREDIBLE, plus is eGo threaded (external threads) and it fits much more snug on the Vamo and doesn't wear out the internal threaded 510 head, in fact I suggest eGo threaded clearomizers they fit more snug, don't wobble and in case you ever strip the 510 threads, you have backups for your backups of your backups
P.S.
This tank is also a very very good one...repeat the same "flavor wick" swap as the mini
You can also run stacked 18350 button top batteries, but you have to have 4x of em, and keep them as mated pairs