Battery Life Resolved
I was extremely delighted with my iPhone4 battery life. With my work exchange mail and gmail set to push and normal use, I could go about two days sometimes without needing to charge. I would go to bed with say 60% charge and wakeup with 58% remaining.
When I installed iOS5, this all came to a crashing halt. Initially I though it was the new iCloud stuff doing an initial sync or backup, but after a few days the drain continued. I tried the multitude of things from rebooting, to turning off location services, removing some unnecessary items from the notification center, pretty much everything in the book. While this alleviated the situation partially, it was nowhere near what it was pre-iOS5.
I read through most of the postings on the Apple forum regarding this issue ( https://discussions.apple.com/thread/3387864 ). One posting in particular mentioned a process taking up 50% cpu. I'm not sure how he measured this process, but it dawn on me to cold boot the phone rather than warm boot. Unlike a computer, warm booting (sliding the red slider after holding the sleep wake button a few seconds) the iPhone saves the state of the apps and presumably the running processes and returns them back to the original state after the phone starts up. If you don't believe, try warm booting and then go into to running tasks (double clicking home bottom) and you'll see all your previously launched apps still there.
To make a long story short, while I did turn off some features (I'll list them below in case it helps some folks) I feel the cold boot is truly what returned the iPhone back to its pre-iOS5 battery consumption. Cold booting is simply holding the home button down while simultaneously holding the sleep/wake button for a few additional seconds after the red slider to shut off appears until it turns off on its own and then pressing the sleep/wake button to turn it back on.
Today it charged to 90% while driving to the office and by lunch time it was 87% -- now that's definitely pre-iOS5 battery life! During lunch, I used it for a while dropping it to 83%. By the time I arrived home in the afternoon it was 80% (I didn't use it much for the remainder of the day). Once home I did a 20 minute jog with RunKeeper gps-tracking me all the time while listening to streaming podcasts via stitcher. Looking at my phone now after a few hours after the jog, its at 69%. So I can claim with certainty, the pre-iOS5 battery life has returned.
So, first thing you should try is cold booting the phone. Just in case it's another culprit, I'll list a few of the other changes I made.
I'm going to reactivate some of the features below one by one over the next few days, even though I do not believe they are the root cause but here they are anyways:
- turned off location services for the weather
- (since it's on the notification center, it's probably always checking location)
- turned off all iCloud features except the features I like the most: contact sync, find my iPhone, photo stream, documents & data, & iCloud backup
- (i thought bookmarks where probably the culprit after realizing the bookmarks are constantly in sync and it coincidentally has a history folder I presumed was syncing constantly as I surfed on my work and home iMacs).