How super-sub-ohm are you below 0.5ohms??? Batteries you are using. Charger you are using. Are you a chain vaper???
Super sub-ohm, or using an exotic coil like a clapton or such, battery Mah rating is out the window as you are pulling massive current out of the battery, Milliamp hours is a rating of for instance 2500mah, at 1ohm would me about 1.25hours of current, or a 2ohm coil could potentially last at 2.5hours, now, 0.5ohms about 30minutes vape time, 0.25ohms about 15minutes, seeing a relationship here??