My average usage time from the stock battery was approx 8 hours if I was actively using the phone. I just got my 3500 battery on Monday, and have only had to charge it once after the initial charge. Current up time (I rebooted just after taking it off the charger) is 79 hours 27 minutes. Awake time is 37 hours and the battery is still at 50%. If you are having battery issues, I have to say the results of this battery are outstanding. I haven't even had a chance to run it through a full 2 cycles yet. I'm still trying to drain it from it's first charge.