Never mind all the camera improvements and edge-to-edge screens and face-scanning security systems. There are two main areas where phones could get better, but never really do: repairability and battery life. The new iPhone 8, with its expensive-to-replace glass back, is a great example of the former. But it's also a perfect example of why battery life does not meaningfully improve.

According to reviews and Apple's own assertions, the iPhone 8's battery life is just about on par with that of the iPhone 7. Sure, it didn't go up, but hey, at least it didn't go down! However, iFixit's teardown of the phone reveals that the iPhone 8's battery is actually smaller than the 7's. The iPhone 8 has a 1821-mAh cell rated for 6.96 Wh of power, compared to the1960-mAh cell rated for 7.45 Wh in its predecessor.

So what gives? The practical answer is that the battery had to shrink to make room for the 8's new inductive charging coils—since, for whatever reason, making a thicker phone is apparently out of the question. Apple managed to avoid a loss in battery life because of better efficiency in iOS and microchips that draw less power, which can eke out power savings that make up the difference.

Win-win, right? Sort of, except that those same power savings could have increased the battery life of the iPhone 8 had its battery not shrunken down to bring things back to the status quo.

That is the battery life conundrum. We've become accustomed to roughly day-long battery life—or, at least, we've agreed to settle for that—and so that is what phonemakers tend to target. Any battery-power surplus that happens to arise is swallowed up in favor of a trim profile or a new power-hungry feature. In fairness, these gains are almost always small, but they could add up over the years if left to accumulate. The only real exception to the rule is when a phone becomes well-known for having a truly awful battery, in which case its successor can claim "fine battery life!" almost as if it were a bonus feature.

This situation isn't the product of malicious design. Rather, it's just an annoying outgrowth of the way the market tends to work. For the most part a phone's battery is either "bad" or "fine," and it seems there's little interest, from phone buyers or makers, in experimenting with giving a phone a truly great battery out of the box. The whole situation is made even worse by the fact that phones' batteries naturally degrade, and so a phone that's "fine" can be "bad" within a year or less. And because phones are hard to repair, a replacement battery can seem like more trouble than its worth, especially when there are brand new phones coming out. Which, of course, plays right into a phonemaker's hands.