30w is the minimum setting when in VT mode...not that it can't throttle down lower than that to limit temps, just that they don't allow the user to set it lower than that as a base setting. That's probably to avoid having to include pre-heat code that may (or may not) be patented. Bigger, established companies like Joyetech can't play fast and loose with patents and copyrights like the small clone shops. For one thing, they're worthwhile targets with serious assets to go after if they can be shown to be infringing.
Anyway, in normal variable wattage mode, it's 1w to 60w (or 50w if resistance is between 0.15 and 0.25).
Though I'm not a fan of sealed battery devices, those LiPo batteries should be good for more than a year, I would imagine.