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Question: FIX FOR: iPhone 4 battery draining fast, phone running hot

I had the same issue many have reported here and in comments on blogs, where their +_battery was draining at least twice as fast_+ as on an iPhone 3GS with iOS 4.

Some threads suggest +_this happens to iPhone 4 when restored from a 3G or 3GS_+, and indeed, that's what I'd done. A few people said that resetting to factory settings and installing everything fresh solved the issue, giving them better battery life than they'd seen on any prior iPhone.

Many of my apps have files or settings stored in them, so I didn't want to have to set everything up again. A fresh install is a real pain.

Deep in an iPhone 3G thread mentioning a similar battery problem after upgrading to iOS 4, someone said they'd deleted all their mail accounts, and set those up fresh, which solved the issue for them. I tried that today, and it worked.


Thursday and Friday, the iPhone 4 went from 100% to 15% in under 6 hours. Today, after this fix, the iPhone 4 is at 87% after 12 hours. Thursday and Friday the phone was hot to the touch whenever I picked it up. Today it's always cool. Apps usage and movement among coverage areas on each day have been exactly the same. The only change was resetting up mail.


Do this on WiFi so you can sync and check mail fast.

1. Delete all mail accounts.

2. If MobileMe user, delete MobileMe account, and remove all Calendars, Contacts, Notes, etc., from the phone (so you don't have dupes when you re-sync).

3. Turn off phone, and back on again.

4. If MobileMe user, add MobileMe account first. I enabled all options, even Find My iPhone (Thursday and Friday I had it off, in case it was using power). Wait long enough for contacts and calendars to sync, check to make sure. I use MobileMe mail on Push.

5. Add back each additional mail account. I have 5. I am in a marginal coverage area, so I set these accounts on Fetch Hourly. I also have "Preview 5 Lines" (I think the default is Preview 2 Lines. This doesn't matter.)

6. Go into Mail, go to the MobileMe Inbox, and scroll your way down letting the messages come in. You can see them come in when you see the Preview Lines update, and then scroll some more.

7. Go into each additional mail account's Inbox, scroll your way down, letting the messages come in.

8. Go to the combined Inbox if you use that, make sure all the messages are in.

9. The WiFi activity spinner may remain spinning even after Mail says it is done Checking Mail. This is because other parts of mail accounts are being synced for the first time. Let the iPhone sit in Mail combined inbox until the spinner stops. Quit Mail, go back in, and watch the spinner after it's done Checking Mail. If the spinner doesn't stop after < 5 seconds or so, let Mail sit again. Once it's caught up, going into mail will Check Mail, and the spinner will stop a few seconds after as it should.

10. You're done.

Hopefully your phone stays cool and your battery life reflects the boost from the 20% larger battery. If not, the next step to try is Reset Network Settings, and finally try a factory reset and installing everything fresh instead of doing a restore. Hopefully you won't need to do that. I didn't.

(a) G5 Quad; (b) Mac Pro; (c) MBP 17"; (d) iMac 24"; (e) iPhone, Mac OS X (10.6.1), (a) 6.5 GB, Apple 30" + Cintiq 21; (b) 4 GB, Dell 30" + Samsung 215TW

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Dec 15, 2010 3:13 PM in response to fujichic In response to fujichic

Hey, that's EXACTLY my problem! I've done everything I could (factory reset, normal 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.

My phone does heats a lot when this happens. I'm very worried.

The problem is that i have to keep deleting my gmail account every time. I mean, erasing solves the problems, but few hours after configuring the gmail account again, the problem happens again. Totally annoying.

Dec 15, 2010 3:13 PM

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Jun 13, 2011 10:38 AM in response to Skeuomorph In response to Skeuomorph

I've had this phone for a little over 3 weeks and didn't have any problems with the battery until last thursday. The battery just drained so fast in only a couple of hours. I've tried just about everything that everyone has suggested to me and nothing has worked. I only have one email account set up on my phone....I'm really nnoyed and frustrated now

Jun 13, 2011 10:38 AM

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Jun 13, 2011 11:10 PM in response to Skeuomorph In response to Skeuomorph

Same thing started happening to my iPhone 4 a few days ago. Except I haven't restored from a 3GS backup. I've just tried disabling Ping, but to no avail. I will now try resetting the network settings to see if that helps. Will report back.

Jun 13, 2011 11:10 PM

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Jun 16, 2011 6:28 AM in response to Skeuomorph In response to Skeuomorph

My iphone 4 just started to warm up and the battery is draining quick. Closed everything and reset to no avail. Turned off bluetooth, increased push time and checked location settings for new applications. Weather Doodle was a bit suspicious as it had a purple direction indicator next to the setting. The only other new app I installed was Lego instruct. I disabled one of the 4 mail accounts I had that is having network difficulties, went to airplane mode and still I see %1 drain every 10 or 15 minutes. I'll remove the new new apps and reset to see if it is related to the new apps. If that doesn't work, I'll try email account reset at home wifi and see if that fixes the issues.

Thank you for the information.

version 4.2.8


Jun 16, 2011 6:28 AM

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Jun 16, 2011 11:26 AM in response to Skeuomorph In response to Skeuomorph

I had this problem appear on my iphone 4 (4.3.3 ATT) last week while travelling. Had been fine since January.

went through extensive testing and trials with Apple support, who finally told methe battery was bad and exchange the phone at a nearby Apple Store.

I went to the store this morning and aquired my brand new phone and within an hour at home the problem started again.

Spoke wiht support who told me I shoudln' have restored my phone (as instructed by the store genius....) and should have tested the battery BEFORE loading any apps.

So, I wiped the phone 2 hours ago and only installed my email and 3 purchased apps (not all 70 I own) ...and yes, already I am losing 1% every 15 mins or so.

So support has told me the battery is probably a problem and I should go to the store AND GET ANOTHER NEW PHONE !

Jun 16, 2011 11:26 AM

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Jun 19, 2011 3:47 PM in response to Skeuomorph In response to Skeuomorph

Issue resolved by updating a password for the exchange email account on my phone for work. we were forced to change the password. I disabled the email account but did not remove the profile from the phone. Still had the issue even in airplane mode. Once I updated the password, reenabled the profile my battery life returned to normal.

To me this is a serious bug in the iPhone email app. Disable should have stopped the reconnection cycle.

Jun 19, 2011 3:47 PM

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Question: FIX FOR: iPhone 4 battery draining fast, phone running hot