Hey, that's EXACTLY my problem! I've done everything I could (restore from zero, reset, erased apps, turned off wi-fi & 3g, disabled push) but the only thing that could fix the battery drain was erasing my gmail exchange account.
Everyone who is facing this problem, please try to delete all mail accounts and give us your feedback.
I believe this must be a major bug on iOS 4.
By erasing my gmail account i just lose my contacts and calendar. That's really annoying.
Do you notice your phone heating a lot when this battery drain happens? My phone does heat a lot.
If you have a Push account (Exchange, Yahoo, Mobile Me, gmail) sometimes the phone loses its connection to the server and opens a new one. But it doesn't close the old one and tries continuously to access the server on a connection that the server no longer recognizes. You have to kill these "stale" connections that can build up over time. What usually works:
1. Go to Settings/Mail,contacts,calendar - tap on the Push account and turn it off (the account, not Push), then back out of settings with the arrow at the top left.
2. Open the mail app so it "sees" that the account is gone. Close the app.
3. Reboot the phone (hold HOME and SLEEP until an Apple logo appears).
4. Go back into Settings and turn the account back on.
If this doesn't fix it, go to Settings/General/Reset and Reset Network Settings, then repeat the above. Finally, if its still a problem, delete the account, reboot, and add it back.
I believe this must be a major bug on iOS 4.
Sorry, it isn't:
New iOS 4.1 is a battery KiLLER!
iOS 4.1 drains battery
Battery Meter/Life Problems with 4.0.2
4.0.2 guzzling my battery. Your's too?
4.0.1 battery life
Battery runs out very quicky in iOS 4.0.1
Battery nearly nonexistant after 4.0 upgrade
Dead battery after few hours on standby using 4.0 software
3.1.3 battery problem
OS 3.1.3 battery issues
3.1.3 upgrade - shortened battery life?
Battery life cut after 3.1.3 update on iPhone 3G
3.1.3 Firmware is a battery killer - how do I back out this upgrade?
Poor battery life with iPhone 3G running 3.1.2
3.1.2 EXTREME battery drain - what gives?
3.1 Battery nightmare
iPhone 3GS with fw 3.1 – battery life gets even worse
Battery Issues with 3.0.1
BATTERY drain with 3.0
upgrade to 3.0 drains my battery
Battery Drain after Update 2.2.1
Battery Life Radically Decreased after 2.2.1 Firmware Update
Thanks for your answer.
But I still think this is a bug, I mean, this should not happen. If there is a connection error when the process try to get push information, it should have a timeout to stop it from being forever consuming battery (assuming that a new process will be created later to get the new mails).
Anyway, I couldn't find an option to 'turn off' the account. I can only turn off the push for that account or delete the whole account.
But thanks a lot for answering!
Go to Settings/Mail,Contacts,Calendar. Find the account name and tap on it. It should have three switches, one each for mail, contacts, and calendar. You should be able to turn them off.
And I agree it is a bug, but Apple doesn't seem to want to fix it. Although it could be a bug in Microsoft Activesync.
This actually really helped me fix the same problem, same symptoms on my iPhone 4. Actually, not sure what caused it, however I changed the setting for my push exchange account to keep unlimited messages on the phone and that might have triggered it. Ever since the battery would just drain in a few hours. Used your method plus switched back to keeping 2 weeks of messages and voila, problemo fixed. Thanks so much for the idea!
Has anyone noticed a severe battery drain due to notifications? I notice a severe drop while Notifications are on. Mail push, high brightness wifi, etc.. all work fine. If i turn on notifications though the battery drops like a rock. I only use notification for one app Roadify every other one in the list is off.
To give an idea, this is my work day routine with the iphone4:
I take my phone off charger going out the door. I listen to ipod for about an hour. (I'm on the subway most this time. No Service)
It sits at my waist all day with an occasional email read or a text coming in. no heavy usage. There is a wifi router above my head, I sometimes have it on but mostly not.
I listen to ipod for another hour. (Again No Service) get home back in the dock it goes.
No Notifications on I get home with about 60-70% charge left
I turned notifications on the other day for Roadify and by the time i got into work I was down to 70% battery. That does not seem normal to me. My understanding is that notifications is like an email push from whatever app has the notifications running. That service shouldn't eat up battery life that badly. Any suggestions?
I have the same issue just with exchange account only syncing contact (no mail, no calendar). Whatever sync or timeout value you have, it will try to connect. It can take op to 3 days, but in the end it will try to connect. And in my case, having no 3G and only turning on Wifi once a day, the battery will drain fast and phone get hot. I found this post interesting: http://www.google.com/support/forum/p/Google+Mobile/thread?tid=5058442512328222& hl=en
I recently upgraded my iphone to iphone 4 from 3GS. When I synced the phone to itunes I used the "restore from previous iphone back-up" option. Through the follwoing days I noticed a very rapid depletion of battery from the moment I took it off charge. I read a lot of the posts here and decided to restore my iphone as a "new phone" -( it does leave you the option of retaining your contacts, notes etc. settings). This resolved my issue completely-battery life is now superior to that of 3GS phone. Note-it does require you to re-sync your songs from itunes). Thanks much to those who suggested doing this-much appreciated.