Ok, so I've drained it twice. The first time was with the charge it came with. Charged it to green light on the charger, took 9 hours. Both times it has lasted me roughly 33 hours. That's including the hours I go without vaping. So I can vape on the 650 all day, charge it overnight and pick it up for the next day. Keep in mind I am a very light vaper though, so ymmv.