batteries are rated by the # of mAh (milli amp hours) and the higher the #, the longer it will hold a charge. So the battery will be bigger, too.
Just for example... a 180 mAh batt will last about 2 hrs. on a charge, depending on your usage... where a 650mAh will last about 3X's as long... and so on...
Precisely, but even more than that.
mAh ratings are usually measured by the manufacturers using very low discharge currents. Under normal (
vaping) discharge currents, lower capacity batteries will suffer a higher efficiency penalty and lose more of their real capacity. It's just something inherent to li-ion/li-po battery technology.
That being said, there's room for smaller batteries and larger batteries.
I use several battery types according to occasion and mood, for example, although if I want to use MF cartos I have to use a 510-808 adapter at this time, usually on something like an eGo (auto or twist).
Here's an MF carto on an eGo(like) 650mAh auto battery (plus a kuwako for the pipe effect):
