Apple's new iOS 11.3 update is a big one.

You see, Apple recently admitted it slows down processors used in iPhone 6, iPhone 6S, iPhone 7, and iPhone SE. These phones have aging lithium-ion batteries that might cause random shutdowns. So, to prevent them from shutting down, Apple pushes out an over-the-air update that throttles their CPUs. And slower performance is a direct side effect. Needless to say, many iPhone owners are unhappy.

In response to all the backlash, Apple began offering cheaper battery replacements for older iPhones and said that a new update - iOS 11.3 - would give users a new Battery Health tool as well as the ability to turn off the iPhone's throttling ("battery management") feature. 

Apple has now released iOS 11.3. Here’s how its Battery Health tool works.

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What does iOS 11.3 bring?

Battery Health (Beta)

For this article, we're focusing only on the battery stuff in iOS 11.3. Now rolling out, iOS 11.3 has a Battery Health tool built into Settings. Just go to Settings > Battery >Battery Health (Beta). 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 throttling ("performance management") feature.

You'll even see whether your iPhone needs service and can subsequently turn off the controversial throttling ("performance management") feature that's throttling your iPhone. And finally, there is one other battery-related change in iOS 11.3, according to Apple:

"iOS 11.3 improves this performance management feature by periodically assessing the level of performance management necessary to avoid unexpected shutdowns. 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."

How to disable throttling on an iPhone

What you need

The ability to disable - and even enable - throttling is only available for certain iPhones, as newer iPhones aren’t affected. Apple recently confirmed the iPhones 8, iPhone 8 Plus, and iPhone X all have hardware updates, so they are unaffected by the throttling ("performance management") feature that it rolled out to unsuspecting customers. So, you need one of the following older devices:

  • iPhone SE, iPhone 6, iPhone 6 Plus, iPhone 6S, iPhone 6S Plus, iPhone 7, and iPhone 7 Plus.

And, obviously, your device needs to be running iOS 11.3, which is now available for consumers.

Go to Settings

After updating your iPhone to iOS 11.3, you’ll notice a new menu under Battery in the Settings app: Battery Health (Beta). 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. (Pocket-lint has a detailed guide on how and where to get your iPhone's battery serviced - whether through Apple, a third party, or yourself.)

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 throttling (the "performance management" feature) until you experience another shutdown. Your iPhone will auto-enable it should that ever happen.

What do those percentages mean?

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In the Battery Health (Beta) 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.

For instance:

  • 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

Apple explained that 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 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.

When will iOS 11.3 be available?

You can grab the iOS 11.3 update now over the air via the Settings app. Go to Settings > General > Software Update. Devices eligible to upgrade include the iPhone 5S and later, the iPad Mini 2 and later, the iPad Air and later, and the sixth-generation iPod touch.

To learn more about the update, go to Apple's newsroom.