Amid complaints that devices running the iOS 5 operating system are still facing battery drain issues even after upgrading to a software update issued on Thursday, Apple has acknowledged that the iOS 5.0.1 has not fixed the problem for some device owners.

According to AllThingsD, Apple's iOS 5.0.1 update did address some of the battery issues. However, the company acknowledged in a statement that there may still be a few problems that need troubleshooting.

The recent iOS software update addressed many of the battery issues that some customers experienced on their iOS 5 devices, Apple said in a statement, We continue to investigate a few remaining issues.

After the iOS 5.0.1 update was released on Thursday, many Apple device users took to Apple's support forums to complain the software update did not solve the battery drain problem and they were still experiencing low battery life.

Installed the new IOS 5.0.1 two hours ago, wrote one user.  Five percent battery drain in 45 minutes with WiFi and location services turned on and me not touching the iPhone 4S.  The new update doesn't seem to help much.

Many users took to Twitter to discuss the issue and, according to some of them, the upgrade actually made the problem worse.

I upgraded to iOS 5.0.1 and my battery life still decreases. It was better on iOS 5.0, but now it's not. Apple haven't improved it, said Vadim Boyko on Twitter.

iPhone 4S has gone down to 34 percent battery in 7 hours... Update never worked, richcovephoto tweeted.

According to a poll conducted on Mashable, more than 900 respondents (32 percent) reported that they were facing the same battery-related issues, even after the iOS 5.0.1 update. For another 350 respondents (12 percent), the battery performance was even worse. However, 600 respondents (21 percent) said that the update had successfully fixed the problem.

The battery drain glitch appeared immediately after the release of the iPhone 4S. The same problem was reported by other iOS device owners after they upgraded to iOS 5. Apple said that a software issue caused the problem and released the iOS 5.0.1 update on Thursday to fix the bug.

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