Y'know, there's another benefit to having a dual battery device. I saw a link to battery lifef that plotted the charge life of batteries, and the less that they are discharged before charging, the greater the number of charges they'll take. 400-500 for fully discharged batteries, 650-700 charges at 50% discharge and 1400 or so at 10% discharge. With the new DNA 40 chips, my Vapor Flask is discharging at about 10% daily on average, so I see my entire setup lasting for years--theoretically...a nice bit of piece of mind, should the zombies inhabit the wourld, or I have a week long business trip. My Ni200 coils are nearly permanent, except for cleaning, my tanks are huge compared to when I started vaping, so all I need is rayon--weightless and available.