iPhone Battery Woes Rooted In Hardware Or Software?

Apple hoped the latest iOS 5.0.1 release would fix the iPhone 4S battery woes. It was disappointed. One problem is that it's unclear whether this is a hardware or software bug. My technical instincts point to the former, but there are anecdotal reasons to blame software.

The logic for hardware as the source of the problem is based on three observations:

1) Most 4S users (myself included) don't experience excessive battery drain, and those who do typically see it right away, before adding apps and tweaking settings. This indicates that the base OS, at least as shipped, doesn't have a systemic problem.

2) The problem doesn't affect other iOS 5 devices, like the iPad 2, iPod Touch, or original iPhone 4. It's more anecdotal evidence, but I upgraded both an iPad 2 and a fourth-generation Touch and have noticed no degradation in battery usage even with heavy use.

3) The reports usually can't trace the battery drain to any specific activity; in fact, many of those affected say they can literally see the battery drain while doing nothing more than watching the home screen.

[ Learn more about Apple's battery problems. Read iOS 5.0.1: The Battery Fix That Wasn't. ]

Thus, the symptoms point to a hardware defect present in some of the new phones. But wait--a report on Monday, again anecdotal but seemingly credible, points the finger at software. An iOS developer has two 4Ses, one that exhibits the battery drain and one that doesn't. According to this account, the devices were purchased on the same day and use the same carrier; he uses one for application testing and the other as his regular phone. The everyday phone had the battery woes, the test device didn't. Here's where the story gets interesting: He factory-reset both handsets and then recovered from a backup. However, rather than reloading them with their original images, he reloaded 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.

And the problem switched devices. The good phone went bad and the formerly bad phone went good, suggesting the problem is unrelated to hardware.

Unfortunately, it's clear there's still a lot we don't know, starting with the scope of the problem. Sure, there are plenty of complaints on Apple's discussion boards--this thread alone has over 5,000 replies--but they hardly represent a statistically relevant sample. Only Apple could gather statistically meaningful diagnostics on the distribution of the battery drain issue, and the company isn't sharing.

Second, there haven't been any rigorous A/B comparison tests of devices exhibiting the problem with those that aren't--the type of head-to-head benchmarking and diagnostics that could isolate hardware, configuration, and performance differences. Apple has likely repeated the switcheroo test described above, and if it can successfully recreate the results, it should be able to methodically diagnose the configuration differences. But again, it isn't sharing.

Many iPhone users, including yours truly, experience very good battery life, so this doesn’t seem like a systemic problem. In my case, the contrast with my previous Android phone, which was lucky to last eight hours on a single charge, is positively striking--my iPhone 4S rarely drops below 75% by the end of even a long day. None of the early published 4S product reviews mentioned abnormal battery drain, and it was only after millions of devices were shipped that reports started surfacing. For those who are seeing a problem, until Apple definitively identifies and publicly describes the root cause and extent, all you can do is continue bugging the Genius Bar and, should Apple's experts prove incapable of fixing things, demand a hardware replacement. Then hope it's not a software problem.