New data supports claims that iPhone 6S performance is poor until old battery is replaced, sparking fresh speculation that Apple intentionally slows down phones

This article is more than 2 years old

This article is more than 2 years old

A new analysis of performance data has reignited the debate over whether Apple intentionally slows down older iPhones.



The data suggests Apple reduces the speed of the processors in iPhones with old and worn batteries, making them slower.

Following user reports that older iPhones with ageing batteries performed worse than the same smartphones with replacement batteries, founder of benchmarking firm Primate Labs John Poole collated data from the company’s Geekbench program that is run on thousands of iPhones.

He found that results from benchmark tests from the iPhone 6S running iOS 10.2 pooled around the expected performance peak showing what the iPhone 6S was capable of without any hindrance.

But from the introduction of iOS 10.2.1 in January 2017, the data showed five peaks – the first matching the maximum performance as with iOS 10.2, but the following four at relatively set intervals showing steps downwards in performance.

The same was seen with tests run on the iPhone 6S running iOS 11.2, which was released in December 2017.

Poole wrote: “The distribution of iPhone 6S scores for iOS 10.2.0 appears unimodal with a peak around the average score. However, the distribution of iPhone 6S scores for iOS 10.2.1 appears multimodal, with one large peak around the average and several smaller peaks around lower scores. Under iOS 11.2.0 the effect is even more pronounced.”

iPhone 7 also affected

The results for the iPhone 7 show a similar pattern. With iOS 10.2, 10.2.1 and 11.1.2, the iPhone 7 results show one large peak at the average maximum performance expected of the smartphone. But iPhone 7s running iOS 11.2 then show one maximum peak followed by three smaller peaks.

“The distribution of iPhone 7 scores under iOS 10.2.0, iOS 10.2.1, and iOS 11.1.2 appears identical. However, the distribution changes with iOS 11.2.0 and starts to look like the iPhone 6S distribution from 10.2.1,” wrote Poole.

Facebook Twitter Pinterest According to Reddit users, who first reported the problem, the reason for the performance differences is due to degrading batteries. Photograph: Reddit.com

According to Reddit users, who first reported the problem, the reason for the performance differences is due to degrading batteries. As a smartphone ages, as does the battery inside.

Most modern lithium-ion batteries inside smartphones are designed to last at least 500 full charge and discharge cycles, which works out to around two years of typical smartphone use.

However, the shorter the battery life and the more a user has to charge it, such as topping up during the day as well as charging over night, the faster the battery will age in relation to the smartphone.

Two key things happen when a battery ages. The first is that its maximum capacity is decreased due to the degradation of certain chemical components inside the cell caused by each charge-discharge cycle. But that oxidation also causes the maximum current the battery can supply to diminish as the battery becomes less efficient.

The first means that you have to charge your phone more, but the second means it may not be able to maintain top performance, as the harder the processor and other components have to work the more current they draw from the battery.

Fixing issues

In November, Apple began replacing batteries in some iPhone 6S models due to problems where the phones would suddenly shut down despite having about 40% charge remaining in the battery.

It later issued a software fix for the problem as part of iOS 10.2.1 for the iPhone 6S.

Poole wrote: “The difference between 10.2.0 and 10.2.1 is too abrupt to be just a function of battery condition. I believe (as do others) that Apple introduced a change to limit performance when battery condition decreases past a certain point.”

Reddit users report that replacing worn batteries alleviates the performance degradation, restoring the iPhone to its original speed.

Developer TeckFire said: “I did a Geekbench score [on an iPhone 6S], and found I was getting 1466 Single and 2512 Multi. This did not change whether I had low power mode on or off.

“After changing my battery, I did another test to check if it was just a placebo. Nope. 2526 Single and 4456 Multi.”

The reduced performance also appears to affect the more recent iPhone 7 as of iOS 11.2. Some have speculated that Apple dynamically reduces performance of older iPhones in relation to both battery wear and current charge. The data from Geekbench indicates that there is more than one reduced performance state.

Poole said users expect their smartphones to perform either at maximum performance or at a reduced performance with a reason, such as when low power mode is activated.

If the iPhone is slow because its processor performance has been reduced to mask a deficiency in battery power, Poole says: “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’.

“This will likely feed into the ‘planned obsolescence’ narrative.”

Apple has not replied to a request to comment by the time of publication.