Hello everyone. I was just curious about 18650 batteries. How long do they last? When should I replace them? How do I tell if I need to replace them? I am currently using a Smoant Battlestar mod, a dual 18650 battery mod. I run this mod at 70w-80w, using pre-built 0.15 ohm coils in my sub-ohm tank. Thanks for any help, and thanks to everyone for helping me with everything in the past.