If you read the links (which I don't recommend) you will see that the exact problem you describe with Exchange accounts has been reported with each release. The problem is not in the release, it is in metadata associated with the Exchange account that is corrupted by the update. I had the problem with 4.0, but it did not recur with 4.0.1 or 4.0.2. What worked for me was the following:
1. Reset Network Settings
2. Reboot.
3. Delete the Exchange account completely.
4. Reboot.
5. Add the Exchange account back.
6. Wait several hours to a day before retesting, because adding the account back results in huge data transfers as the iphone syncs up with the Exchange server.
There are other suggestions throughout the forums. One is to delete the .ipsw file to force iTunes to redownload the update, then Erase all content and settings on the phone, then Restore as a new phone.
Another is to convince your IT department to reboot the Exchange server.
Tried this again last night. I reset network settings, rebooted, deleted both Exchange accounts, rebooted. Then I manually populated every Exchange folder until it stopped "downloading..." (which took hours!). I then fully charged the phone before I went to bed, and took it off charge, not touching it after that. This morning, 7 hours later, it's accumulated 22 minutes of usage and lost 3% of the battery.
Hi everyone guys,
I don't know if anyone else write the same that i'm going to before, because the thread is so long i didn't read it all.
Anyway i had the exact same problem in the past days, battery lasted 20h without even using the phone, and night time I could see it dropping from 100% to 60% only resting in stand by.
I did the Exchange Profiles Reset and that really helped a lot, battery wouldn't loose power in stand by so quicly anymore. But battery life was far beyond accettable anyway.
So. I tried a lot of configuration and only one thing really made the difference for me.
I turned off Face Time.
I noticed in the past day that even without surfing the web or using apps requiring an internet connection, the transmitted data counter was growing up at a rate of 40 kb per hours anyway. Turning Off Face Time put an end to this data transfer in background and at the same time my battery life is now the way it should be!
At this moment I have a stand by time of 31 h and usage time of 5 h and the battery is at 50%. Before it never passed the 24th hour of stand by, using it or not.
Hope this could help anybody, and really excuse me if this was already posted or reported.
after many tests and phone calls to Apple support, probably I found the cause of poor battery life on iPhone 4: FaceTime.
If I keep FaceTime on, the phone continues to send data over the cellular line (even if on Wifi network), so it drains the battery really quickly (ie. 3%/hour in standby).
Try this: disable Facetime, reset your network settings by the General menu of the Settings and -to be sure- unplug your microsim from the phone and then put it back.
You will see there will be no more cellular data even on standby, and the battery will thank you 🙂
To me, the phone was sucking about 20% on standby during the night, while now on the same conditions (and Facetime off) it takes 2% !
There's something wrong with your phone. See this and other threads, especially the ones about deleting and recreating your mail accounts, rebooting after the delete.
