So I just update 3 days ago to an iPhone 3GS (second hand) and updated it to iOS 4.1 and unlocked it. But it's suffering from extreme battery drainage from 100% to 0% in 5 hours in stand by mode, so I didn't know exactly what the problem was. I read on some threads that it could be a mobilesubstrate error and that I should downgrade it, which I did but it didn't help. So I decided to restore the iPhone and make a log of time vs battery percentage and install one by one each cydia app that I use and see which one was causing the problem, I did all that and found out that none of them were causing the problem, after installing all my cydia apps, the battery was great only from 100% to 92% in ~6 hours, so I proceeded to install my regular app store apps in batches of 3 to see if I could narrow it down, long story short, as soon as I installed one app with push notifications and opened it and allow it to do push notifications, my battery drainage came back. Even after disabling push notifications the problem was there, also after uninstalling every app store app. The thing is, my push notifications are not working either way since the hacktivation processes makes push notifications unusable and push fix and push doctor are not compatible with iOS 4.1. I don't have an AT&T sim card to activate the phone through iTunes and then unlocking, so I don't know if that will help, I ordered one on Ebay and I should be getting it on Monday so I will report back after. So to all of you who are having problems with battery drainage: - Do your push notifications work? - Did you hacktivate it? - Even after turning off push notifications, battery drainage is there try restoring your iPhone as new and see if the battery drainage persists even without apps that use push notifications. - I am thinking that because the hacktivation process messes up these notifications, a connection is kept alive constantly which drains the battery. But even on my old iPhone 3G without push fix, the problem was not there. Can you tell me if the problems you are experiencing are also related to push? By the way, I also tested push gmail and that is not the source of the problem, push mail works fine.