According to research carried out for me by an iPhone app developer, the battery issue that some iPhone 4 and 4S owners are experiencing is not, as some have suggested, related to the hardware.
The developer, who at this point wishes to remain anonymous, approached me late last week to discuss the issues he was experiencing with one of his two iPhone 4S handset. The problem he was seeing was pretty much along the lines of what others are reporting - rapid drop in battery when the handset is doing little or nothing.
Nothing new there, but what I thought was interesting was that he had two handsets, one that was displaying the battery problem that some people are screaming about, and another that wasn't. He admitted that the two handsets were very different in their configuration and had different apps installed. One was a test bed for apps he develops, the other was his day-to-day use handset. It was his day-to-day handset that was displaying the battery problems.
Both handsets were bought at the same time (direct from Apple for delivery on launch day), both are connected to the same network (AT&T) and both handsets are now running iOS 5.0.1. This to me was strong evidence to suggest that the problem affecting iPhone handsets was not a hardware issue. However, so that we could totally rule out this being a hardware problem the developer took things a step further. He factory reset both handsets and then recovered them from a backup. However, rather than reloading them with their original backup, he swapped them over. He reloading his day-to-day handset with the backup from his development handset, and loaded the development handset with the backup from his regular day-to-day handset.
Would the battery problem stay with a specific handset or swap over with the software?
The problem jumped handsets. Now the handset that was his development test bed (but loaded with the apps and settings from his day-to-day handset) is displaying the battery drain problem. The other handset (the one that was displaying the problem), is showing excellent battery life.
Note: This is a sample of one so bear that in mind. Ideally I'd like to try this with multiple handsets, but I don't have access to armloads of iPhones.
The problem, it seems, is down to software. What exactly (whether it's an app or set of apps, or a setting somewhere), we're still not sure. However, I am now convinced that this problem ISN'T a hardware issue and will eventually be fixed by a software update.
Sidenote: As an aside, I think that iOS 5.0.1 has introduced the battery bug to my iPhone 4. Typically the handset would drop about 3 - 4% battery capacity overnight (around 7 hours). Since installing iOS 5.0.1 I've noticed a much bigger drop of around 15 - 20% with no change in how I'm using the handset. I'll keep a closer eye on this over the next few days and see if the pattern holds true.