The iPhone 4S has reported problems of faster than usual battery drainage. Apple engineers are currently looking into solving the problem that has affected its latest smartphone.

The Guardian reported that some iPhone owners are now being contacted by Apple after complaining about their batter performance problems. One 4S owner tells The Guardian that an Apple engineer responded giving him instructions for installing a diagnostic file on his phone so it can be sent back to the company for investigation. There haven't been any updates on this user's experience yet.

Other users are also saying they have similar problems of really fast drainage even with minimal use. In some cases, owners said their iPhones lasted no more than a few hours regardless of usage and disabled features.

Launched a mere two weeks ago, the iPhone series has traditionally sealed the battery internally. Unlike most other phones, therefore, users are unable to swap batteries. This poses an even more serious issue for Apple to solve as quickly as possible. According to iFixit, the battery of the 4S compared to the iPhone 4's battery life is not too much better. On average, the 4S gives owners an extra .05 watt-hours' capacity.

Some owners seem to be blaming Siri for the unusually short battery life, but Apple says it's likely due to other issues. Although the 4S does pack the more powerful dual-core processor A5, other explanations are pointing to corrupted contacts from Apple's MobileMe and iCloud services. Google's Contacts may also be a cause, but some people found that deleting and reinstalling somewhat fixes the problem. Others tried backing up their iPhone content and then restoring it to improve battery life.

With so many unsatisfied 4S owners posting to discussion boards, Apple's support is definitely taking the issue seriously and reaching out to users one by one. Most people that have been contacted are finding Apple engineers friendly and helpful with their situations, admitting that there are problems causing the short battery life.

The Guardian also performed their own test on an unrestored iPhone 4S. They found that running MobileMe and Google Contacts by far drained the phone faster than Wi-Fi, location services, and Siri do.