Hi Brian, welcome aboard!
Yes, the Tesla VV/VW uses the 18650 size battery. They do come in different mAh ratings, I have some that are 3100. The mAh rating is a rough guide to how long they'll go before needing to be recharged. The higher the rating, the longer they'll last. Actual run time depends on power setting, of course, but also on style of
vaping. Chain
vaping will shorten it compared to other types, and long draws will as well.
Just get a few extra batteries (you need more than one, anyway!) and a proper battery box to carry them with you.
Most regulated mods will shut down around 3.2 volts, since you really don't want to run your battery lower than that. And some do a better job at the lower end than others.
Lithium batteries will drop from the full charge value (4.2/4.1) to about 3.8 fairly quickly, then stay there for quite some time. Once they get down to 3.6, they do tend to complete the "fall" quickly, so I tend to swap out around that point anyway. Their life can be extended (service life, not vape time) by charging early.
