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I got my iPhone 5 this week.

While browsing with Safari, on WiFi (which I am using to post this question), my battery life drops at a steady rate of 1% per 5 minutes. I have been timing it from 64% to 56%, and its been exactly constant for each percentage point.

All widgets are off and I have double-tapped the Home button to make sure Safari is the only app running.

5 minutes times 100 percentage points comes out to about 8 hours and 20 minutes, but Apple says it should last up to 10 hours browsing on WiFi.

Am I just being OCD or is my battery a little weak?

How much deviance from the estimated time is normal?

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I've read that Apple tests with the minimum brightness. What's your drain when your brightness is all of the way down? –  Kalamane Oct 2 '12 at 22:03
    
Some things use more battery than others. Push, Location Services, etc. –  GEdgar Oct 9 '12 at 12:21
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3 Answers

up vote 2 down vote accepted

While quite possibly you do end up with a lower battery life in your tests than the one advertised, you need to take into account the following:

Test conditions

Many factors will determine the outcome when testing the battery life, like signal strength, iPhone settings, screen brightness, the actual websites being loaded, background processes and much more. FYI, apple discloses it's test conditions, you can read about them here. If you truly want to compare, you should as best as possible mimic the test conditions Apple used.

Test accuracy

While I have no problem taking you for your word your battery drops 1 percent exactly every 5 minutes while browsing, that doesn't necessarily mean you end up with 8 hours and 20 minutes of battery life. There is quite a large margin for error when you only sample such a small period, and the only real way of checking Apple's claims would be by actually trying to surf the web for 10 consecutive hours.

Concluding, while Apple's test conditions are semi-optimal for their testing results, they have a better reputation for test accuracy than some other manufacturers. They do test the iPhone with almost factory default settings, but specifically for browsing the actual web sites being loaded can still make a noticeable difference in the test results.

From the info you provided, your battery seems perfectly fine to me and within the margins of difference one would expect.

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Another thing to add is that the battery meter itself isn't perfectly accurate; it's just an estimate. For instance, I've seen my battery drop from 20% to 10% in an hour (you get an alert for each), then hang on for hours and hours longer between 10% and empty. Other times it's the reverse. Etc. –  daGUY Nov 29 '12 at 15:09
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I like to run some tests with each new iPhone where I charge it fully and then run it down without charging. When the device shuts itself off, you get a logfile showing how long the device ran and how long it slept.

Incident Identifier: 5FABC917-4A0C-4DB4-992C-517B046AB02B
CrashReporter Key:   f8fa10d17990b92b51f4af68531ed318840a78e6
Date:                2012-09-27 17:39:56 -0500
OS Version:          iPhone OS 6.0 (10A405)

SpringBoard: com.apple.springboard.idle NoIdleSleepAssertion == 255, held for 02:06:50

Hardware Model: N42AP
Awake Time: 09:20:37 (33636)
Standby Time: 18:26:05 (66365)
Partial Charge: 0
Capacity: 0
Voltage: 3401 mV

In this case, the device ran for more than 9 hours and 20 minutes before it needed to shut itself down. Each battery is different, but you can tell a batter is starting to lose capacity when the Awake Time starts to drop an hour or more instead of holding mostly steady.

Since voltage (and amp-hour estimates) decrease non-linearly and the % remaining is a well-modeled but educated guess, the best plan is to measure the whole charge a few times to see how your settings match your expectations.

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As far as deviance from normal, you would need thousands of these logs and the only collection I am aware of is if you submit diagnostic logs to Apple, then they will have a nice collection of these real world data points to ensure they tune their software stack to meet the battery estimates they have determined in factory testing before release of the product. –  bmike Oct 2 '12 at 22:49
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I've found the iPhone 5 to be extremely sensitive to the quality and strength of cellular connection, much more so that other phones I've owned, but this is to the credit of Apple.

On the positive side this has resulted in the loss of only 6% - yes, 6% - in 7.5 hours with very light use, staying in a location with excellent 3G signal strength and, presumably, no tower hand-off as I was relatively static during that time.

The flipside is the expected mediocre performance when travelling in and out of varying coverage, with the battery being in the low 20s after about 10 hours. I should point out this is in line with my experiences with other smartphones though, so not a poor reflection on the iPhone 5.

Overall I find it slightly better than any of my previous Android devices, easily managing a full day of normal use, but it will inevitably struggle to see the day out if used for long periods e.g. waiting at an airport or on a train ride.

I should point out that my phone is an A1429 GSM model on the Vodafone UK network which, at time of writing, doesn't offer LTE.

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