iOS 12.1 Extends Battery-Related Performance Management Feature to iPhone 8, iPhone 8 Plus, and iPhone X

Apple on Tuesday released iOS 12.1 following six weeks of beta testing. As mentioned in the release notes, the software update extends Apple's performance management feature to the iPhone 8, iPhone 8 Plus, and iPhone X.

iphone x battery
From the release notes:

Adds a performance management feature to prevent the device from unexpectedly shutting down, including the option to disable this feature if an unexpected shutdown occurs, for iPhone X, iPhone 8 and iPhone 8 Plus.

Apple has reflected this change on its iPhone Battery and Performance website, noting that performance management "may be less noticeable" on those iPhone models due to their "more advanced hardware and software design."

The performance management system was first enabled in iOS 10.2.1, but it was limited to the iPhone 6, iPhone 6 Plus, iPhone 6s, iPhone 6s Plus, iPhone SE, iPhone 7, and iPhone 7 Plus until yesterday's release of iOS 12.1.

Last December, Apple did mention that the design of the iPhone 8, iPhone 8 Plus, and iPhone X allows for a "different" performance management system that "more precisely" prevents unexpected shutdowns, but prior to iOS 12.1, no performance management feature of this kind had been enabled on the trio of iPhones:

iPhone 8 and later use a more advanced hardware and software design that provides a more accurate estimation of both power needs and the battery's power capability to maximize overall system performance. This allows a different performance management system that more precisely allows iOS to anticipate and avoid an unexpected shutdown. As a result, the impacts of performance management may be less noticeable on iPhone 8 and later. Over time, the rechargeable batteries in all iPhone models will diminish in their capacity and peak performance and will eventually need to be replaced.

Why is Apple slowing down some iPhone models if necessary?

From our January 2018 article What to Know About Apple Slowing Down iPhones to Prevent Unexpected Shutdowns:

iPhones, like many other consumer electronics, are powered by lithium-ion batteries, which have a limited lifespan. As the battery in your iPhone ages, its ability to hold a charge slowly diminishes.

A chemically aging battery can also have increased impedance, reducing its ability to provide a sudden burst of power when demanded by other components in an iPhone, such as the CPU and GPU. A battery's impedance will also temporarily increase when it has a low charge and/or in cold temperatures.

A battery with a high enough impedance may be unable to provide power quickly enough to the iPhone when needed, and Apple safeguards components against the drop in voltage by shutting down the device.

Apple recognized that iPhones unexpectedly shutting down on users is not a good experience, and starting with iOS 10.2.1, it quietly implemented a power management feature to prevent these shutdowns. The update was released in January 2017, and a month later, Apple said it saw a major reduction in shutdowns.

The performance management feature can be disabled if desired in the Settings app, under the Battery Health menu. At this time, the feature does not appear to extend to the new iPhone XS, iPhone XS Max, or iPhone XR.

Top Rated Comments

1144557 Avatar
31 months ago
I'd be fine with it if the battery lasted more than a single year before needing it. In fairness it's probably only a small group where the battery is bad enough to need throttling but even so, for the price of the phone the batteries should have better longevity.
Blame battery tech not Apple. Apple didn't invent lithium-ion batteries. They simply chemically degrade over time due to charge and discharge cycles. No devices (not just smartphones) are immune from battery degradation. Same reason your cordless dustbuster/stick vac battery wont hold a charge after a certain amount of time; it has nothing to do with the device the battery is in but number or charge/discharge cycles.

Seems like a problem that could have been solved if Apple bothered to ship their phones with an appropriately sized battery...
Huh? What does battery capacity have to do with number recharge cycles and chemical degradation of a lithium-ion battery? ALL batteries degrade over time.


"The lithium-ion battery works on ion movement between the positive and negative electrodes. In theory such a mechanism should work forever, but cycling, elevated temperature and aging decrease the performance over time. Manufacturers take a conservative approach and specify the life of Li-ion in most consumer products as being between 300 and 500 discharge/charge cycles."

Temperature 40% charge 100% charge
0°C 98% (after 1 year) 94% (after 1 year)
25°C 96% (after 1 year) 80% (after 1 year)
40°C 85% (after 1 year) 65% (after 1 year)
60°C 75% (after 1 year) 60% (after 3 months)

So charge cycles and ambient temperature make a HUGE difference in life of a battery. And since no one keeps their devices at 0°C (freezing point) and factoring most charge the battery to 100% each time, a 20% degradation after 1 year per the chart is proven by science. It's not simply "Apple said"
Score: 19 Votes (Like | Disagree)
NexusUser Avatar
31 months ago
Seems like a problem that could have been solved if Apple bothered to ship their phones with an appropriately sized battery...
Score: 16 Votes (Like | Disagree)
neliason Avatar
31 months ago
Apple’s management of batteries across devices is odd. Why doesn’t iPad have a low power mode? More importantly why doesn’t iPad have a battery health report? These are important features for all devices and not just the one’s Apple decides to surreptitiously tinker with.
Score: 13 Votes (Like | Disagree)
gnipgnop Avatar
31 months ago
Why doesn’t iPad have a low power mode?.
Because the overall size of the battery plays a role in whether or not it can supply the proper voltage under certain conditions. The iPad battery does not have the same constraints as the smaller iPhone batteries.
Score: 11 Votes (Like | Disagree)
BulkSlash Avatar
31 months ago
Totally fine with me. Better than a phone becoming unusable, but of course they've should've been disclosing it and allowing users to toggle it on and off from the beginning.
I'd be fine with it if the battery lasted more than a single year before needing it. In fairness it's probably only a small group where the battery is bad enough to need throttling but even so, for the price of the phone the batteries should have better longevity.
Score: 9 Votes (Like | Disagree)
Nicksd84 Avatar
31 months ago
Totally fine with me. Better than a phone becoming unusable, but of course they've should've been disclosing it and allowing users to toggle it on and off from the beginning.
Score: 8 Votes (Like | Disagree)

Top Stories

imac pro featured black

Apple Confirms iMac Pro Will Be Discontinued When Supplies Run Out, Recommends 27-Inch iMac

Saturday March 6, 2021 7:33 am PST by
Apple on late Friday evening added a "while supplies last" notice to its iMac Pro product page worldwide, and removed all upgrade options for the computer, leaving only the standard configuration available to order for now. We've since confirmed with Apple that when supplies run out, the iMac Pro will no longer be available whatsoever. Apple says the latest 27-inch iMac introduced in August...
bloodoxygenapplewatch

Apple Watch Series 7 to Gain Breakthrough New Health Feature

Friday March 5, 2021 5:34 am PST by
Apple is reportedly planning to bring a new, first-of-its-kind health technology to the Apple Watch Series 7, in what could be a breakthrough for managing conditions such as diabetes more easily. According to a recent report from ETNews, the Apple Watch Series 7 will feature blood glucose monitoring via a non-invasive optical sensor. Measuring blood glucose levels, also known as blood...
Top Stories 48

Top Stories: iPhone 13 Leaks, OLED iPads and Macs, New AirTags Evidence

Saturday March 6, 2021 6:00 am PST by
iPhone rumors are heating up, with noted analyst Ming-Chi Kuo this week releasing a wide-ranging report outlining his expectations for the iPhone lineup over the next three years. This week also saw rumors about OLED displays potentially coming to iPad and Mac starting next year, increasing signs of AirTags functionality in iOS 14.5 betas, and more, so check out all of the details below! i...
apple products refurbished store banner

Class Action Lawsuit Over Apple Providing Refurbished Replacement Devices Proceeding to Trial in August

Friday March 5, 2021 9:53 am PST by
Initially filed in 2016, a class action lawsuit that accuses Apple of violating the Magnusson-Moss Warranty Act, Song-Beverly Consumer Warranty Act, and other U.S. laws by providing customers with refurbished replacement devices is set to proceed to trial August 16, according to a notice this week from law firm Hagens Berman Sobol Shapiro LLP. Apple's repair terms and conditions state that,...
Oled iPads and MackBook Pro

OLED 10.9-Inch iPad Rumored for Early 2022, 12.9-Inch iPad Pro and 16-Inch MacBook Pro Could Follow

Thursday March 4, 2021 8:37 pm PST by
Earlier today, DigiTimes shared a preview of an upcoming report claiming that Apple is working on both iPad and Mac notebook models with OLED displays that could launch starting in 2022. The full report from DigiTimes is now available, and it includes several new alleged details about Apple's plans. According to the report, the first of these devices to adopt an OLED display is likely to be...
iPhone 13 Notch Feature2

iPhone 13 Rumor Recap: Smaller Notch, Larger Batteries, 120Hz for Pro Models, Improved 5G, Wi-Fi 6E, and More

Friday March 5, 2021 8:20 am PST by
While we are likely at least six months away from Apple unveiling the so-called iPhone 13 lineup, rumors about the devices are starting to accumulate, so we've put together this recap of everything that is expected so far. The upcoming iPhone 13 lineup will consist of the same four models and the same screen sizes as the iPhone 12 lineup, according to reputable analyst Ming-Chi Kuo,...
imac pro while supplies last

iMac Pro No Longer Custom Configurable, Available 'While Supplies Last'

Friday March 5, 2021 10:14 pm PST by
Apple appears to be on the verge of discontinuing the iMac Pro, with the store page for the high-end all-in-one Mac including a "While supplies last" tagline and only the base model with no custom configurations available for purchase. The iMac Pro launched in December 2017, and while there have been a few tweaks to the available configurations over the years, it has received no substantial...
hlh030121feafutureoffitness012 1614286673

A Look Inside Apple's 23,000 Square-Foot Fitness+ Studio

Friday March 5, 2021 10:59 am PST by
Apple Fitness+, the latest service to join the Apple family, integrates tightly with the Apple Watch to offer a comprehensive and growing selection of workout and exercise videos made by a team of professional trainers. Apple Fitness+ Studio (via Men's Health) Apple curates and records all of the videos at a location in Santa Monica, California, and each video features a similar background...
maxresdefault

What's on Your iPhone Home Screen?

Thursday March 4, 2021 10:31 am PST by
Over on our YouTube channel, MacRumors videographer Dan has a new video up where he shares his Home Screen, wallpaper, and all of his current favorite widgets. Subscribe to the MacRumors YouTube channel for more videos. Check out Dan's video to see his setup, and then comment below and show us your own Home Screens. It's always fun to see other peoples' Home Screens, and with widgets and...
microsoft edge vertical tabs

Microsoft Edge 89 Brings Vertical Tabs and New History View

Friday March 5, 2021 4:06 am PST by
Microsoft has officially released version 89 of its popular Chromium-based Edge browser, bringing its long-trialed vertical tabs feature to Mac for the first time. Vertical tabs are intended to make more efficient use of screen space, and should prove a welcome addition for users browsing on 16:9 ratio displays in particular. Users can click vertical tabs to switch between them and...