Read "Baditudes" battery related blogs. The 18350's will not provide much run time especially if you're wrapping lower ohm coils. They also have a lower amp rating, not making them ideal for sub-ohm vaping IMO. The 18650 if its the 1600mah version should be fine, I believe it has a 20 amp rating. You may wanna grab a few more 18500/18650's. I can usually tell when battery voltage drops by the way it's hitting. That said...I test battery voltage with a Multi Meter to determine the charge status after using one, or charging one. Ideally you'll wanna keep at least one spare with you. Change it out a little sooner than normal if your concerned about over-draining it.