It took my istick 40 about 3.5 hours to go from completely dead to fully charged. I feel that the battery in it is over specced as well. It is suppose to be 2600 mah. I never got more than 5-6 hours out of it. Granted I live with my e cig practically glued to my lips, but that still seems not very good to me. I didn't have the money to buy two at the time, so I was living next to outlets lol.
I'm over the moon with my two new dual 18650 mods now though. I'll never go back to a mod with built in lipo batteries. Even with my heavy vaping habit I still get an entire days worth out of two fully charged 18650s. And if my batteries do end up dieing, then I can simply swap in two new charged batteries and I'm good to go right away.
I'm not trying to thrash isticks with lipos. Mine served me very well for 3 months. It is the device that kept me off of cigarettes for good. And for that reason it holds a special place in my heart. Just not good battery life