Some iPhone users and bloggers are reporting that older iPhones updated to iOS 6 are draining their batteries much faster than before, and sometime heating up during or after recharging.

Based on posts at Apple's online support boards and other online forums, it's difficult to know what the cause or causes are, and how widespread the problem is. The boards are replete with complex experiments by users trying a wide range of fixes to the battery life problem.

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Yet iPhone 5, with a bigger screen, LTE support, and a more powerful CPU seems to have excellent battery life. InformationWeek's Eric Zeman noted the discrepancy as he was reviewing the newest iPhone. "Combined, these [new features] might have been a disaster for the iPhone 5's battery life," he wrote in a blog post this week. "Instead, the slightly larger battery in the iPhone 5 and the way the A6 processor handles iOS 6 means excellent power management."

"But iOS 6 isn't as friendly to the iPhone 4S and iPhone 4 when it comes to battery life," he writes. "I've installed iOS 6 on both the iPhone 4S and 4, and, have noticed, along with other users, that battery life has taken a pretty big hit on these older iPhones."

At least a few users say they see similar battery life drops running iOS 6 on their iPads. According to one of Zeman's commenters, Mike Schmidt, "Same here. I upgraded my iPhone 4 and my iPad 3 and both have very much reduced battery life. So much so, that I missed taking some more pics at the Ryder Cup yesterday in Chicago. I may go back to IOS5 and hope the problem clears up."

A Network World request to Apple public relations about this issue had not yet received an acknowledgement when this story was posted.

One discussion thread on Apple's support boards, "iOS 6 iPhone 4s battery drain," had just over 116,000 views and nearly 800 comments by Monday afternoon, Oct. 1. Another thread, "Is iOS 6 draining iPhone 4 battery faster?" had 40,718 views and 247 replies.

"I'm using an iPhone 4S and with iOS5 I had to recharge it every 2 days," posted Vincentthu. "Since iOS 6 I need several recharge a day and my wifi is not working anymore (Greyed out - that's another problem). My solution: Deactivate 'cellular data' and deactivate 3G. I removed GPS too and SIRI and all options are deactivated. Notifications are turned off. Now it's better but my phone is as usefull as a Nokia from the 90's."

Some users are finding shockingly fast battery drains. "I updated to IOS6 last night and my ip4 went from 36-48 hours between charges to draining completely and dying from 6:30am to 11am this morning, mostly just sitting in my pocket," posted Thedjprice. "*** apple unacceptable. I used the device for roughly 30-45 minutes and the rest of the time it sat in my pocket."

One common recommendation, often from Apple staff at the company's retail stores or from other users online, was to reset one's phone as a "new phone." But that didn't work for lcroke0002, who did it four times, twice at an Apple retail store, "all to no avail," he posted. "I have run 3 battery cycles and turned off/on all types of apps (Apple and non-Apple). Battery and heat issues still exist." On Sunday night, he got a phone call "from an Apple tech who monitors the boards and he had me install a battery profile on my phone" to create a file of activity. According to the tech, it's a software issue. "Tonight I will speak to him again and send the file the profile is creating. Hopefully, this gets resolved quickly."

One of the baffling aspects to the problem is its lack of consistency. "This also doesn't happen every time," posted another user, Grayum Baker. "For example, I was home all day yesterday and my battery worked normally. Then, last evening it started draining almost 1% every minute or two. I read an article earlier in the day that recommended Reset All Settings and force quitting all active background apps. I did that late last evening and still had the problem. I turned off Siri. Still draining. At bedtime I turned the phone off while recharging. This morning the battey seems to be normal again."

Some users stumbled on apparent solutions. TracyLynnT deleted her Facebook account from the iOS 6 integrated Facebook feature in Settings. "I started thinking that since the FB integration updates your contacts and calendar it is probably constantly receiving data," she wrote. "My battery seems to be back to normal after doing that."

Another, annafromcapon bridge, said she logged out of her Facebook app, and "turned off all the iCloud stuff except for 'Find My Iphone' and my battery is back to normal. Now I access FB using the Chrome browser. I leave Safari off most of the time (unless is autoloads when I click on a link in an email, for example). My notifications and location settings were already at a minimum. I also drained the battery and then charged it overnight. Battery is back to the way it was before IOS 6 update."

But those kinds of "fixes" had other users grumbling. ChicagoBubba noted that he was now routinely turning off Cellular Data to conserve battery. "I see many people are willing to just shut things off freely, and I can't understand any justification for doing so," he wrote. "Why buy an iPhone just to cripple it and say you only text and make calls anyway? In that case these people might be better off with a simple flip phone."

"I found something that "works" but it's not really a fix and is really really annoying," posted Resterix, who with his wife and a friend all had factory-unlocked iPhone 4S models. "If I turn off 3g and cellular data, and then do a hard restart of the phone, we can go all day and only lose about 15% of battery life. Once I turn 3g or cellular data on, even with all apps closed, we'll lose 1% every 3-5 minutes on standby."

He describes a maddeningly manual sequence of events: "So, if i'm out and want to use data, I have to go into settings, turn on 3g and cellular data. Do the thing I wanted to do. Then, go back into settings, turn off 3g and cellular and then do a hard restart.. I am thinking it has something to do with the factory unlocked iphones, as my friends who have carrier locked phones don't seem to have any battery issues."

John Cox covers wireless networking and mobile computing for Network World. Twitter: [email protected]

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