Apple Confirms that it Slows Down Older iPhones Due to Aging Batteries

Apple Confirms that it Slows Down Older iPhones Due to Aging Batteries

We normally don’t cover topics related to Apple products on XDA-Developers, but recent iPhone-related news has drawn a lot of attention from Android users. Apple has confirmed that it intentionally slows down older iPhones in order to extend the functional lifetime and prevent aging lithium ion batteries from shutting down the devices.

If you’re confused, you’re not alone. For some background information, many users have been complained that their iPhone started to feel slow after owning it for a few years. The devices said to be affected were the iPhone 6, the iPhone 6s, and the iPhone SE. Although Apple didn’t release any statement at the time, the issue came to the forefront again when the iPhone 7 received the iOS 11.2 update. Users started to make the same complaint: their devices were slowing down.


It turns out, their devices were slowing down due to intentional behavior in iOS. This was confirmed by investigations from two developers. First, Primate Labs researcher John Poole investigated the issue after discovering that a changed battery on his iPhone 6s resulted in performance being almost doubled. We have previously interviewed Mr. Poole on XDA regarding the release of his Geekbench 4 benchmark in 2016.

Mr. Poole confirmed the increase in performance of his iPhone 6s via multiple tests. Although iOS told him that the phone had only had a battery level of 20%, the performance increase was much more than that. So he plotted the kernel density of Geekbench 4 scores for the iPhone 6s on multiple iOS versions. iOS 10.2 turned out to be the version where the performance of the device showed signs of being throttled. With iOS 11.2, the effect became even more pronounced.

On repeating the tests with an iPhone 7, Mr. Poole found that the same thing was happening on the newer device. On the iPhone 7, iOS 10.2.1 was not the affected version; instead, the impact was seen in iOS 11.2. He also stated that he believes the problem to be widespread.

Image Source: Primate Labs

Secondly, iOS developer Guilherme Rambo‏ followed up Mr. Poole’s work and found the existence of ‘Powerd’ in iOS code: a power mode which he stated to be “responsible for controlling the CPU/GPU speed and power usage based on iPhone battery health.” Apart from having a failsafe to make sure that users’ iPhones and iPads don’t catch fire, Powerd is said to “increasingly slow down your device as your battery degrades” while working independently of Low Power Mode in iOS.

In response, Apple confirmed that the software process is working as intended (that is, slowing down CPU and GPU speeds on detection of poor battery health), and stated:

Our goal is to deliver the best experience for customers, which includes overall performance and prolonging the life of their devices. Lithium-ion batteries become less capable of supplying peak current demands when in cold conditions, have a low battery charge or as they age over time, which can result in the device unexpectedly shutting down to protect its electronic components.

Last year we released a feature for iPhone 6, iPhone 6s and iPhone SE to smooth out the instantaneous peaks only when needed to prevent the device from unexpectedly shutting down during these conditions. We’ve now extended that feature to iPhone 7 with iOS 11.2, and plan to add support for other products in the future.

What Apple is doing does make some sense as lithium-ion batteries do have a characteristic of degrading over time. As such, the amount of power stored and the peak current does drop. Obviously, there are variations and some batteries last longer than others, but without access to data, it’s difficult to say whether iPhone batteries are specifically vulnerable to aging at an abnormally fast rate.

As it is, the facts are that Apple is choosing the smaller of two evils here by deciding to slow down users’ devices in order to let them remain functional. The alternative is to do nothing, which may have led to devices shutting down early. Owners of certain devices such as the Nexus 5X and Nexus 6P have had devices becoming inoperable due to this issue, so it’s certainly plausible. However, the lack of transparency by Apple has led some to believe that this move is intentionally designed to entice users into upgrading to a newer device.

What would be the real step forward? The answer: batteries which don’t spontaneously degrade at a quick rate. We will be watching for developments in this space.

Source 1: Primate Labs Source 2: The Verge

About author

Idrees Patel
Idrees Patel

Idrees Patel is a smartphone enthusiast from India. He has been an Android user since the time he got the LG Optimus One in 2011. He has a bachelor's degree in Management Studies. The subjects in which he is interested are mobile processors, real-world UI performance, in-depth camera quality analysis, and many more. Contact him at [email protected]

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