iPhone owners have discovered that replacing the battery in an old phone can boost its speed, suggesting that Apple is limiting the processing speed on phones with older batteries.

Benchmark data from Geekbench backs up that theory, according to the company's founder.

Lots of conspiracy theories say Apple slows down old devices to encourage customers to get new iPhones.



One way to spruce up an aging iPhone is to replace its battery. It costs $79 from Apple, and while it's not like purchasing a new phone, it's a lot cheaper and should help your phone last a full day.

In fact, replacing your battery might even speed up your old iPhone.

Reddit users discovered last week that shortly after the battery on an old iPhone was replaced, benchmark tests — which measure a computer's processor speed — saw a dramatic and noticeable increase in performance.

But new data from Geekbench backs up what those Reddit posters said. Geekbench is one of the most commonly used iOS speed tests, so John Poole, its developer, pulled the data.

A typical Geekbench distribution should show one big peak — that's the score an iPhone model should get when it's running at full strength, and iPhones of the same model should get about the same score.

But Poole found that the benchmark distributions of iPhone 6, iPhone 6S, and iPhone 7 units running any version of iOS newer than 10.2.1 had multiple peaks — suggesting a software limitation was restricting some devices to a slower processor speed.

Older phones had more-pronounced peaks.

Here's the distribution he found for the iPhone 6S:

This suggests Apple is slowing down the processor on phones with older batteries, presumably to boost performance. But some will point to the findings to say that Apple is purposely slowing down older iPhones to sell new phones. (Google searches for "iPhone slow" spike shortly before a new iPhone is released.)

"I believe (as do others) that Apple introduced a change to limit performance when battery condition decreases past a certain point," Poole wrote.

Apple didn't immediately return a request for comment.

Poole surmises that his findings are the result of a software fix Apple released in February as part of the iOS 10.2.1 update. That update was a response to reports of older iPhones shutting down randomly with 30% battery life left, and reducing the iPhone's processor speed could have helped address the issue.

Apple told Business Insider at the time: "The diagnostic data we've received from upgraders shows that for this small percentage of users experiencing the issue, we're seeing a more than 80% reduction in iPhone 6s and over 70% reduction on iPhone 6 of devices unexpectedly shutting down."

"This fix will also cause users to think, 'My phone is slow so I should replace it,' not, 'My phone is slow so I should replace its battery,'" Poole wrote. "This will likely feed into the 'planned obsolescence' narrative."

All batteries will eventually start to fail, as they have a limited lifespan.

Apple says its batteries should still have 80% of their original capacity after 500 charges. However, Apple expects an iPhone to get three years of use, so if you charge your iPhone every night, you might want to get a new battery before its third year of service.

Not only will it help your phone last an entire day — it might give it a speed boost too.