Since Apple released the iPhone 4S Oct. 14, owners have complained about serious battery drain issues compared to previous models. After hours of tinkering, Oliver Haslam from iDownloadBlog appears to have a solution.

It appears that iOS5's [golden master] release introduced a bug that causes the Setting Time Zone function to keep the location tracking circuitry running constantly, draining battery power considerably, Haslam writes. 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.

Haslam has reportedly tested this method on four different iPhone 4S handsets, as well as an iPhone 4 and an iPhone 3GS running iOS 5. All phones demonstrated greatly improved battery life after switching Setting Time Zone off.

To turn off the Setting Time Zone function, visit the phone's Settings application, then choose Location Services and visit System Services at the very bottom of the screen. Find Setting Time Zone, which will be the second to last option from the bottom, and toggle it off.

When battery complaints began to arise soon after the launch of the iPhone 4S, Apple, based in Cupertino, Calif.,  was reportedly not even close to finding a fix. Some users were experiencing drops in battery life as much as 10 percent every hour. When a British user posted his battery issues online, he received a call from a senior Apple engineer.

[The Apple engineer] admitted this was an issue and asked lots of questions about my usage and then asked if he could install the file below and that he would call back the day after to retrieve the info, the user said. I extracted the file from my Mac after a sync and e-mailed it to him. He was incredibly helpful and apologetic in the typical Apple way!

The iPhone 4S varies in a few significant ways from its predecessor, the iPhone 4. The new model actually has .05 more watt-hours capacity than the iPhone 4, according to online repair guide producer iFixit, but features a more dynamic dual-core A5 processor, a more powerful 8-megapixel camera that can shoot video in full 1080p HD, and a dual antenna system to maximize reception. The phone also comes with Siri, a voice-activated personal assistant, which many believed was the real source of the battery drain.

On Oct. 28, Apple began shipping the iPhone 4S to 22 more countries, including Mexico, Italy and Spain, and has plans to ship the new smartphone to 70 more by Dec. 31.