iOS 11.3 will add a Battery Health menu, this is how it works

Apple has revealed the new Battery Health menu that will allow users to disable speed throttling that was implemented by Apple to preserve the battery health of the phone. The company also shared how the new functions will work, and they have also mentioned that the iPhone 8 and X will not be slowed down when the battery performance degrades.

iOS will start slowing down when the battery capacity drops below 80% which will usually take roughly, 2 years or after 500 charge cycle. The new menu will be able to show the battery capacity and if the phone shuts down on its own a message will be displayed in the menu saying “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…”

Once this happens you will have the option to disable the throttling but you will not be able to turn it back on unless the phone shuts down on its on again. Once it goes below 80% a new message will pop-up and indicate that a battery replacement is required.

Lastly, if you have acquired a pre-used iPhone and the menu cant detect the battery capacity, that could mean that there is an issue with the iPhone or the previous owner has installed a third-party battery which is not supported by Apple.