Bloggers and users have been registering their discontent with iPhone 4S' battery performance for weeks now, while some early-adopters have complained about the handset overheating.
MacWorld's Chris Breen may have found a cause that could be related to both issues; he discovered with a system activity monitor that the processes 'dataaccessd' and 'CrashReport' were spiking processor usage, and draining the battery in the process.
"The combination of crash reports provided by the iPhone and System Activity Monitor helped me determine that I had an issue with contact syncing that caused my iPhone to drain with alarming rapidity. But wiping the phone and syncing via iCloud solved the problem. Yet it did so the second time rather than the first. Why? I haven’t a clue," Breen explained.
On the other hand, Oliver Haslam writing for iDownloadBlog, places the blame for battery problems on a bug in iOS 5 that makes Location Tracking constantly try to update the coordinates, which is exhausting for the battery. Haslam suggests a solution for this problem: Settings > Location Services > System Services and toggle Setting Time Zone to off.
Other fixes for the battery drain include turning off Sync With This iPhone Over Wi-Fi in iTunes's iPhone Summary pane, or stopping error reports from being sent to Apple by going to Settings > General > Usage > About > Diagnostics & Usage and choosing Don't Send.
Discontented users have reported on various forums that when they took the new iPhone to Apple Service and had it replaced, the problem disappeared.