(Pocket-lint) - In 2017, Apple revealed it slows down older iPhones such as the iPhone 6, iPhone 6S, iPhone 7, and the first generation iPhone SE in order to prevent unexpected shut downs by managing the performance peaks.
The performance management feature - or throttling as some have described it in the past - is also included on the iPhone 8, 8 Plus, iPhone X, iPhone XS, iPhone XS Max and iPhone XR, but it only kicks in after an unexpected shutdown first occurs on a device with a battery that has diminished ability to deliver maximum instantaneous power.
Apple iPhones from the iPhone 6 and later also have a Battery Health tool that was introduced with iOS 11.3 back in March 2018, along with the ability to turn off the iPhone's battery management feature. Here is everything you need to know about Apple iPhone's Battery Health and performance management features and how to control them.
What is the iPhone performance management feature?
Apple's performance management feature is specific to iPhones and it's designed to prevent a device from unexpectedly shutting down so the device can still be used. Unexpected shutdowns can occur for a number of reasons, be that extreme cold temperatures, or a device with a battery of high chemical age, for example.
Apple's iOS software will dynamically manage performance peaks in order to manage shutdowns. It looks at a combination of things, like device temperature, battery state of charge and battery impedance. The software then assesses whether action is required and if it is, the maximum performance of some of the system components, like the GPU and CPU, will be managed in order to balance out workloads and allow for a smoother performance overall.
Some of the things you might notice when the performance feature has kicked in are: Longer app launch times, lower frame rates when scrolling, backlight dimming, lower speaker volume, gradual frame-rate reduction in some apps, disabled camera flash in extreme cases and apps refreshing in the background may require reloading upon launch.
Some of the things that won't be impacted by the performance feature are: Mobile call quality and networking performance, captured photo and video quality, GPS performance, location accuracy, sensors like gyroscope, accelerometer, barometer and Apple Pay.
With regards to the performance management feature, Apple describes it as: "If the battery health is able to support the observed peak power requirements, the amount of performance management will be lowered. If an unexpected shutdown occurs again, then performance management will increase. This assessment is ongoing, allowing more adaptive performance management."
What is the Battery Health feature?
Apple iPhones running iOS 11.3 and later have a Battery Health tool built in. To access the tool, go to Settings > Battery > Battery Health. From there, you'll see information about your iPhone's maximum capacity and peak performance capability.
You'll also see if your iPhone is being slowed by Apple's performance management feature.
For example, we have an older iPhone XR showing as having a 94 percent battery capacity. Apple is not yet throttling the phone though: "Your battery is currently supporting normal peak performance".
In the Battery Health feature, you'll also see whether your iPhone needs service and you can subsequently turn off the controversial performance management feature that's throttling your iPhone if you want to.
How to disable throttling on an iPhone
The ability to disable - and even enable - throttling is only available for iPhones more than a year old running iOS 11.3 and later.
Under Battery in the Settings app you'll notice the Battery Health option. Tap it. You'll then see a screen with a link to more information about lithium ion batteries. Below that, you'll see your battery's maximum capacity.
If this indicator is under 80 per cent, you'll see another message at the bottom of the screen that warns your iPhone's battery is "significantly degraded". There will be another link that will point you to a page about how to get your phone serviced.
Disable 'performance management' feature
If your device has shutdown due to battery degradation, this same screen will tell you that "performance management has been applied to prevent this from happening again".
There will also be an option to disable the throttling. You can't enable the performance management feature until you experience another shutdown. Your iPhone will auto-enable it should that ever happen.
It's also worth noting that "all iPhone models include fundamental performance management to ensure that the battery and overall system operates as designed and internal components are protected. This includes behaviour in hot or cold temperatures, as well as internal voltage management. This type of performance management is required for safety and expected function, and cannot be turned off".
What do those percentages mean?
In the Battery Health menu, you'll see a percentage that indicates your iPhone battery's maximum capacity, followed by a message explaining your iPhone battery's peak performance capability. The message you get depends on the percentage shown.
- 100 percent: Your battery is currently supporting normal peak performance.
- 95 percent: This iPhone has experienced an unexpected shutdown because the battery was unable to deliver the necessary peak power. Performance management has been applied to help prevent this from happening again. Disable...
- 79 percent or less: Your battery's health is significantly degraded. An Apple Authorized Service Provider can replace the battery to restore full performance and capacity. More about service options…
- Unknown: This iPhone is unable to determine battery health. An Apple Authorized Service Provider can service the battery. More about service options…
Maximum capacity and peak performance
Maximum battery capacity measures your iPhone's battery capacity relative to when it was new. Batteries will start at 100 per cent when first activated and will have a lower capacity as the battery ages. According to Apple, a normal battery is designed to retain up to 80 per cent of its original capacity at 500 complete charge cycles when operating under normal conditions.
Now, as far as peak performance capability goes, it is the ability of your iPhone's battery to supply adequate charge. If your iPhone's battery maximum capacity is under 80 per cent, then its health has been significantly degraded and it needs replacing.