iPhone 4S "issue" with Battery.

Apple engineers have begun contacting iPhone 4S owners about a known "issue" with its battery.
Ever since the iPhone 4S hit stores two weeks ago, owners have been complaining of inexplicable drops in the iPhone 4S' battery, even during standby.

When Apple CEO Tim Cook launched the iPhone 4S, he promised a longer battery life. In PCMag's review of a Sprint iPhone 4S, lead mobile analyst Sascha Segan said the iPhone 4S got 7 hours, 33 minutes of 3G talk time, versus 6 hours, 17 minutes on a Verizon iPhone 4.
Users get an extra .

05 WHrs of juice compared with the battery that was in the iPhone 4. But is that enough to compensate for power consumed by the iPhone 4S' dual-core A5 processor?
Meanwhile, Sprint iPhone 4S owners have also been complaining about slow data speeds. See Sprint: iPhone 4S Isn't Crushing Our Network for more. Apple's iPhone 4S, as did its predecessor, has a problem.

The scope of the battery issue isn't clear: Apple did not respond to a request to provide more information about claims from iPhone 4S users about poor battery life.
But the growing thread of complaints about poor iPhone 4S battery life on Apple's iPhone support forum--1,327 replies and 100,349 views as of 1:32pm PT on Friday, and 1,384 replies and 101,567 views an hour later--suggests more than a handful of Apple customers are dissatisfied.

According to a report in The Guardian, Apple engineers have been contacting some iPhone 4S customers and asking them to install performance profiling software. iOS 5 already includes a capability to report diagnostic information to Apple, with user consent. Presumably, the standard diagnostic routines do not provide data that Apple engineers need to identify the issue.

Speculation about the source of the power drain has suggested a number of possible culprits related to iPhone 4S features: iCloud, Siri, Location Services, Bluetooth, Calendar/Reminder Sync, and automated diagnostic transmissions to Apple, among others.
Some users report being able to improve battery performance by disabling various network access and location data settings, and restoring only necessary services.