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I just upgraded from a 3GS to a 4s and my battery life is dramatically worse. I wasn't expecting it to be the same (though I was hoping that it might even be better), but I'm seeing a big difference. Since I have the same settings as I did previously, I don't think the problem has to do with any configuration differences (for example, I have email set to check manually on both). I was even running on iOS 5 on the 3GS, so I can't really point to that either. Siri is one software bit which is 4s only, but I can't imagine that is the culprit as I don't think it would always be running.

I've restarted the phone to make sure that no out of control process is running in the background.

So is the iPhone 4s just that much worse for battery life or do I have questionable hardware? Is there any easy way to troubleshoot (can Xcode be used to measure usage)?

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@XAleXOwnZX There is no "bedding in" time. The moment you turn on your new phone, the battery is at it's strongest, only getting weaker with time (seeing a reduction in charge cycles). –  cksum Oct 23 '11 at 1:38
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@XAleXOwnZX Do you have a source for this? Where did you hear it? –  cksum Oct 23 '11 at 4:14
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@Richard No. They have recommended that users fully charge their batteries but a full cycling is only recommended once per month to maintain peak battery performance. They stress to keep the electrons flowing, and Macs made after 2008 all readily condition the battery, so that's no longer necessary (mobile devices never needed this). They also have never spoken of batteries needing a "bedding in" time nor that new batteries require some use to reach their maximum capacity. That seems contrary to how batteries work, which is why I'm curious about the source of such rumor. –  cksum Oct 23 '11 at 4:39
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Again, what the full battery cycling does is allow the battery monitoring systems to recalibrate themselves (because of the way they work, laptop battery meters effectively integrate battery current over time. If there is offset in the integration system, (which is unavoidable), over time, the monitor's idea of the battery state-of-charge and the real state-of-charge will diverge). It is not good or bad for the battery in any other way then a normal discharge cycle is, in that is wastes some of the batteries (limited) life. –  Fake Name Oct 23 '11 at 7:58
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Anyways, the whole concept of "keeping the electrons moving" is just word salad. Unless your battery is operating at 0° kelvin (−273.15 °C), the electrons are already moving. –  Fake Name Oct 23 '11 at 8:04

3 Answers 3

It's anecdotal, but John Gruber (of Daring Fireball) who tends to get a lot of feedback from Apple users, suggested on Twitter that it's a problem for some non-zero percentage of users:

And my iPhone 4S's battery lasts HALF a day, where the 4's battery lasted 1,5 days

@JMoVS I know you're not alone, that other 4S users are seeing short battery life, but that's not normal. Mine lasts as long or longer.

So it sounds like you may have got a dud. If your battery life is substantially worse than a 3GS, it may be worthwhile asking to have your unit swapped for a fresh one.

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I've also seen several tweets from Chris Breen that indicate that his iPhone 4S has a shorter battery life than the 4. –  Kyle Cronin Oct 23 '11 at 2:01

Every time there's a new iPhone, a certain subset of people immediately claim that the new one's battery life is way worse than the old one. Fact: every iPhone's battery has been better than the one preceding it. Not saying your problem isn't real - it probably is - but one of two things is causing it:

  1. a software issue
  2. a defective battery specifically in your phone

Since no one here can help you with 2., we're all going to suggest the basics that Apple helpfully already summarized for us:

And I'd add that any battery-draining issues in iOS 5.0 are probably going to be fixed in the inevitable version to follow.

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Thanks you. support.apple.com/kb/ht4137, like I keep posting on this site, the iPhone has battery issues related to some sort of weirdness from previous backups or from some sort of software glitch, a restore as new generally fixes it. –  hobs Oct 23 '11 at 1:54
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Actually, the 4S is rated at 200 hours of standby time, whereas the 4 is rated at 300 hours. These numbers don't mean much in an absolute sense, but they indicate that compared to each other the 4S has ~2/3 the standby time of the 4. So no, not every iPhone has longer life than the previous one. –  Kyle Cronin Oct 23 '11 at 1:58
    
Keep in mind, I had my 3gs running on iOS 5 before upgrading and I still have it and was continuing to use it as an iPod. So other than Siri, there should be no software difference between the two so it should be possible to remove the software as the culprit unless there is something about Siri that runs constantly and is draining the battery. And I think there is a third potential issue that is "the iPhone 4s has worse battery life than the 3gs", be it due to the A5, the multiband cell radio or something else. Dismissing that as a possibility seems rather naive. –  Tim Oct 23 '11 at 4:31
up vote 0 down vote accepted

So it sounds like this is likely a known issue, as described by this article in the UK Guardian.

In case anyone else comes across this and is curious about some of the symptoms I've seen, here is a bit of info that might be useful:

  • I had my phone go from 90% charge to 60% charge in 90 minutes while in airplane mode and without using the phone (no apps running, no location services being used, no iPod usage).
  • The phone gets quite warm when the battery is draining. Much more so than I experience when doing anything else. Given the behavior, I'd guess that it gets into some mode where an app gets out of control and is fully pegging the CPU, even though as far as can be determined, nothing is/should be running.
  • This may be a red herring, but my phone won't sync. I don't know if this is related, but doing either a restore or trying to sync with iTunes while connected to a MBP fails. I can only get things to work with "Transfer Purchases". I sync fine with my iPad running iOS5, so I don't think the problem is on the iTunes side. This may be an unrelated problem (though I hope it isn't as there is a chance I'll get a fix for the battery problem).

Hope this helps others who run into a similar problem and are trying to troubleshoot it. I think the easiest way of testing is using airplane mode and making sure location services are not running and if you are still seeing rapid battery drain, there is no good reason that should be happening in that mode, no matter how you have your phone set up.

NOTE: And now confirmed by Apple.

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"This may be a red herring, but my phone won't sync." It sounds like you have software issues and I'd be careful about assuming your problems are similar to those Apple is testing for. If you can't sync and an app is using 100% CPU, then it's probably a fix that will require you completely reset the settings on your device or reinstall iOS 5 and set it up as a new phone (you can pull your iCloud data when you log in). Without doing that first, your guess is as good as ours as to why you're not seeing a lengthy battery life. –  cksum Oct 29 '11 at 5:41
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Took it in, got a replacement phone and have had excellent battery life since. Syncing still not so good. –  Tim Nov 1 '11 at 23:14

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