You got it Ren. As you get more experience with the setup you're using, you will get better at estimating battery voltage from the way it's vaping. I can usually tell when my batts get to around 3.6V which is the lowest I like to go. OTOH, with new coils installed I have a couple of times vaped them down to 2.7V without realizing it. After a couple of years of vaping mech mods, that doesn't happen to me any more.