iOS 11.3 is going to be a pretty major update, and one of its most notable tweaks is in response to one of the bigger PR controversies to hit Apple in recent times. It recently became apparent that iOS contains a feature to slow down older iPhones’ processors when their batteries degrade to the point that they’re no longer able to deliver peak performance; Apple says it’s designed to prevent the phones from unexpectedly shutting down altogether.

A lot of people were unhappy with the revelation, and Apple responded by cutting the price of an iPhone battery replacement from $79 to $29 and pledging to give users the ability to turn off the throttling in iOS 11.3. That ability has now arrived in versions of iOS 11.3 rolling out to developers; it should come to public beta testers within the next few days, and it’ll likely be available in a final release within the coming weeks — whenever it does arrive on your phone, here’s how to use it for yourself.

First of all, you’ll need to be running iOS 11.3 — which, at this point, requires some waiting and a few extra steps. Apple hasn’t said when the final version will be released, but anyone can register their device to receive beta builds of the software. The battery management features were only added in the second beta version, so you’ll need to update even if you downloaded the first iOS 11.3 beta last month.

Ordinarily we wouldn’t advise installing beta software on a primary device, because it often isn’t stable — that’s why it’s in beta. If you’re running into serious performance issues because of power management in earlier versions of iOS, however, it might be worth making an exception this time.

You can sign up for public betas at this website. The process involves installing a profile to your device that will seed it with beta software updates rather than the final, official versions. Once the profile is installed, restart your phone and check for a software update as usual in the Settings app. If you want to get off the beta track, you can delete the profile and update the next time a final iOS version is released.

The ability to enable and disable throttling is only available for certain phones, since newer models aren’t affected — Apple says the iPhones 8, 8 Plus, and X all have hardware updates to make such dramatic power management unnecessary. Of course, that doesn’t necessarily preclude Apple from releasing a similar feature in the future, when millions of 2017-vintage iPhones are suffering from depleted batteries. In any case, this iOS 11.3 feature only applies to the iPhone SE, 6, 6 Plus, 6S, 6S Plus, 7, and 7 Plus for now.

Upon updating one of these phones to iOS 11.3, you’ll notice a new page under Battery in the Settings app. Tap “Battery Health (Beta) and you’ll see a page that starts off with a link to more information about how lithium ion batteries work. Below that, there’s an indicator of your battery’s maximum capacity. If this is under 80 percent, there’ll be a message at the bottom of the screen saying that the battery’s health is “significantly degraded” along with a link detailing how to get it serviced. (You may be in for a long wait.)

If your device has experienced a shutdown due to battery degradation — which could happen with a given battery health of as high as 95 percent — the page will tell you that “performance management has been applied to prevent this from happening again” along with the option to disable the throttling. You can’t turn this back on until you get another unexpected shutdown, at which point it will automatically be re-enabled.

It’s not quite a simple throttle that you can turn on and off as the mood takes you, then. It’s clear that Apple still believes that its default approach to power management is the right one for most users. But if you really want to be sure that your older iPhone is working as fast as possible, the option is now there.

https://www.theverge.com/2018/2/7/16984234/how-to-iphone-throttling-ios-11-3