Since updating to iOS 5.1 I have had mixed results with battery life.
Overall there is an improvement but I could not understand why some days the battery drains in 12 hours and other days it goes for 2 full days.
I have eventually figured out what it is that I do that is different and it comes from a suggestion that comes from a post much earlier in this thread from another user.
When your iPhone battery dies and your phone turns off, your natural instinct is to immediately go plug it in and start charging. Everytime I do this my battery life is not so good after that charge cycle has completed.
Instead when the phone powers off, leave it off for around 30-60 minutes before plugging it in again and let it sit at least an hour more on the charger after it shows 100%.
I have done tests with this over the last two weeks and sure enough everytime I don't do the above I get poor battery life.
Last night I was down to 5% and instead of trying to run it down to 1% and let it shut down, I manually held down the power button > slide to power off and then left it off for around 35 minutes before I charged it overnight. This morning I am at 42 minutes usage, 5 hours 13 minutes Standby and still have 96% battery remaining.
As for my phone setup / services that I use:
- Location Services OFF
- iCloud (ON) - Contacts, Calendar, Bookmarks, Photo Stream, Documents & Data
- iCloud Phone Backup over WiFi (OFF)
- 3G (OFF)
- Cellular Data (OFF unless I leave home / office)
- Brightness (AUTO)
- Mail (PUSH OFF / Collect Every 15 mins - 2 IMAP Accounts)
- FaceTime (ON)
- Music/Video (Home Sharing ON)
- WiFi (ON) Ask To Join Networks (OFF)
- BlueTooth (OFF)
- iTunes WiFi Sync (OFF)
- Siri (OFF)
As you can see I do not turn OFF all the wonderful features of the iPhone as is sugested by so many people, I actually can't get on board with suggestions like that because it makes the iPhone pointless to me. I have proven to myself I can run all the things I want and still get good battery life. I have been using the above settings since day one and it's been 3 months now and there is a marked improvement in my battery life using the above approach to recharging.
2 Bugs I have picked up on iOS 5.1:
After ever restart of the iPhone, 3G is ON and BlueTooth is ON, not sure why Apple cannot make these switches stick? Check your phone everytime after reboot / restart and make sure your Bluetooth and 3G (if you have the toggle) are turned off so they don't chew your battery.
