I just bought one for my 18650's. I can tell you that it evaluates the battery and either charges if needed or doesn't if it doesn't need it (in the case of mixing up bats rotation which I have done). Charge time for dead battery is faster than I thought it would be. I wanna say just shy of a couple of hours. Also, its supposed to stop charging when done, and you can leave it on the rest of the night (if I forget to unplug it). Haven't really tried that yet, its normally done so soon I just unplug the unit and put away. I didn't want to run into leaving it on and running down the charge time on my new bats so I invested in a good charger and so far (3 weeks now) I am happy with it.