iPhone battery drain

Good read from cnet


Having initially pointed out customer complaints about subpar battery life in the iPhone 4S, the U.K.'s Guardian newspaper has followed up with a report about a possible culprit and a possible temporary fix.

The Guardian said yesterday that some 4S users who had griped on Apple's support Web site about the power drain were being contacted by the company and sent diagnostic files that could be sent back to Apple for analysis. Numerous users have been saying their phones are lasting just a few hours, even with minimal use, the Guardian said.

Now the paper reports that a location-based feature in the phone that detects when you've physically moved to a different time zone and then resets the phone's clock accordingly may be the problem.

Apparently, the "Setting Time Zone" feature is polling cell phone towers constantly to determine the phone's location rather than doing so only on occasion. The phone's location-tracking setup triangulates information on the power of cell tower signals in order to situate the device.


The Guardian quotes Oliver Haslam, of iDownloadBlog:

It appears that iOS 5?s GM release introduced a bug that causes the Setting Time Zone function to keep the location tracking circuitry running constantly, draining battery power considerably. Switching it off may mean that your iPhone will no longer set its own time zone when you travel, but that's a small price to pay for having your iPhone last more than 12 hours on a full charge...We have tested this method on 4 different iPhone 4S handsets, including an iPhone 4 and an iPhone 3GS. All have reported drastically improved battery life after switching "Setting Time Zone" off.



The Guardian reported that some users have seen little difference after switching off the feature and that Apple itself has not yet weighed in on what the specific issue might be. But Haslam's temporary fix seems worth a shot.

"Setting Time Zone" is found under Settings/Location Services/System Services.

The iPhone 4S launched two weeks ago in the U.S., Canada, the U.K., and several other countries, and expanded to 22 additional countries yesterday. It boasts an extra hour of 3G talk time compared with the iPhone 4, while coming in at 100 hours less of standby time, based on Apple's own testing. CNET's own iPhone 4S battery testing with a model on Sprint's network yielded 9.2 hours of talk time on the carrier's 3G EV-DO Revision A network, coming in as the strongest iPhone battery test to date.

The phone continues the trend set by previous iterations, sealing the battery inside to allow for better use of space. As a side effect, users can't swap it out with another battery, as most other phones allow.

A teardown of the iPhone 4S earlier this month by iFixit revealed that the battery in the 4S is slightly more powerful than the one in the iPhone 4 but not by much. Users get an extra .05 WHrs of juice compared with the battery that was in the iPhone 4. The big difference, of course, is that the iPhone 4S sports a dual-core a5 processor.