If you have an iPhone or indeed, an iPad, we presume you will have now downloaded the latest iOS 5.0.1 upgrade for your device. It was made available at the end of last week, promising to iron out a few problems from the first iOS upgrade, with battery problems the main focus. Has it worked? Not quite, it seems.Apple has made an official statement on the upgrade and battery problems. Speaking to the All Things D site, it said: 'The recent iOS software update addressed many of the battery issues that some customers experienced on their iOS 5 devices. We continue to investigate a few remaining issues.' Doesn't exactly fill you with confidence, does it? Obviously it's a tough one to call for Apple. Not everyone is suffering with the battery problems, so it's not something that the company has found easy to replicate. Indeed, it has contacted some owners to install software to track potential problems. That should at least make the problem easier to pinpoint.In some cases, Apple's research might well have helped in reducing or eradicating the problem. But according to BGR, some Apple users are complaining that the update has actually made things worse. 'After upgrading to 5.0.1 my iPhone is draining the battery even faster,' said just one of many users on the Apple forums. Some have reported a 50% loss of charge in less than two hours.If that's widespread, you can see why Apple is continuing to investigate. A phone that runs out of juice at the end of your morning commute isn't exactly a lot of use. iOS 5.0.2 might well be here sooner than we would have thought.