iPhone 4S battery drain - Is it the handset or iOS 5 that's at fault?

Three handsets in a head-to-head drain-off!

[UPDATE: Apple has released the iOS 5.0.1 update which incorporates a bug fix for the battery drain issue. Download via iTunes or over the air.]

I'm hearing a lot of complaints from iPhone owners, specifically owners of the new 4S handset, who claim that they're not getting good mileage from their battery. But is it the iPhone 4S that's to blame, or iOS 5?

Want to get more from your iPhone battery? Check out these iOS 5 battery saver tips!

Sascha Segan of PCMag carries out a test, putting a new iPhone 4S running iOS 5 up against an iPhone 4 running iOS 4 and another running iOS 5. The results are interesting in that basically there's little difference in the time taken for the battery to run out between the three handsets.

  • iPhone 4/iOS 5 - 6 hrs 55 mins
  • iPhone 4S/iOS 5 - 7 hrs 27 mins
  • iPhone 4/iOS 4 - 7 hrs 29 mins

Here's a timelapse video of the three handsets ... I warn you in advance, it's not that exciting!

Conclusion - It's iOS 5, not the iPhone 4S.

But ... it's not that clear cut. I'm hearing from some iPhone 4S owners who aren't seeing any problems, and others who are seeing their battery literally drain away in front of their eyes. Other people are seeing the same issue on the iPhone 4 and iPhone 3GS with iOS 5, while others aren't seeing any problems at all. Something is going on, that's for sure, but it's hard to put a finger on what the issue actually is. Personally, I think the problem comes down to usage, which means that Apple will have to rely on telemetry sent from handsets to narrow down the cause.