Apple engineers are contacting some iPhone 4S users after its support forums were flooded with complaints about poor battery life and overheating handsets.

Though the official documentation accompanying the iPhone 4S reveals that its battery life would be less than previous models, clocking it at around 200 hours rather than 300, some early adopters have complained that power to the handset drains after around eight hours' usage.

Apple has contacted some users to ask questions about usage and in some cases has asked people to install monitoring software so it can get to the bottom of the problem. While some believe that the recent iOS 5 update could be to blame, The Guardian offers one potential fix, citing the ‘Setting Time Zone’ feature as a potential culprit.

The Guardian writes: “Location services can prompt large drains on any smartphone’s battery: they use a combination of the Wi-Fi network name, where available, plus mobile mast data and GPS sensor input, to calculate the phone’s position. The mobile mast data, for example, is usually calculated by comparing the strength of signals from the three nearest phone masts and triangulating against them. However if such a calculation is made too often, by polling the masts, it will begin to use battery power unnecessarily.”

Location services can be turned off manually by heading to Settings -> Location Services -> scroll to bottom to System Services -> Setting Time Zone.

The official Apple support forums are currently awash with users speculating as to what could be causing the battery drain and a number of potential fixes have been suggested, including re-installing imported contacts.

An official statement, and hopefully a quick-fix, from Apple is expected after a thorough investigation. If you don't want to wait until then, you could try searching the Apple support forums for some possible fixes.