As promised, Apple has included a new section in Settings -> Battery to include battery health information. Battery Status (Beta) available on iOS 11.3 and later and is displayed on all models starting with iPhone 6. You can view the estimated battery capacity and the screen explains if iPhone battery performance is optimal. iOS will now tell you on this screen if your device is slowed down due to a worn out battery.
When you upgrade to iOS 11.3, a new performance management feature will be activated on the device. The device will be automatically adjusted by reducing iPhone battery performance when the system first experiences an unexpected shutdown. In this case, you can also choose to disable performance management by going to the screen Battery status.
Apple claims that all devices with iOS 11.3 start with the function performance management disabled. Performance management reduces the CPU capacity if the battery can no longer provide peak power.
Currently, performance management can be enabled by the system on iPhone 6, iPhone 6 Plus, iPhone 6s, iPhone 6s Plus, iPhone SE, iPhone 7 and iPhone 7 Plus. IPads are not affected by this limitation as they have much larger batteries which take much longer to degrade.
iPhone 8 and iPhone X will have new hardware upgrades that allow Apple to apply power management on demand, so the limitation on these devices will be much less obvious than previous iPhones.
The capacity of iPhone battery performance can be viewed on any iDevice introduced from 2014 onwards, starting with iPhone 6. You must have iOS 11.3, then go to Settings -> Software update if you haven't downloaded this iOS version yet. After the update, open Settings -> Battery -> Battery status (beta).
The maximum capacity reading provides an estimate of the amount of total capacity that the battery can hold. The new phones should report 100% capacity. A lower capacity means that the iPhone reduces the duration between recharges.
The second section entitled "Maximum performance capacity". You must read the gray text below this section to see if battery management is activated (ie the limitation).
When your iPhone undergoes an unexpected shutdown, it enables the limitation of power management. When the device restarts, a notification on the lock screen alerts you that a sudden shutdown happened. The notice say something like: "This iPhone has suffered an unexpected shutdown because the battery was unable to provide the necessary peak power. Performance management has been applied to prevent it from happening again". Read on to find out how to disable it, if you want to risk sudden stops.
If the battery is still in good health to provide peak power (maximum capacity 90% / 100%), it is confirmed that the battery is supporting the maximum possible performance. In this case you cannot enable or disable anything.
If the iPhone stops unexpectedly because it cannot support maximum performance, the device will enter the state performance management enabled. Performance management slows down the CPU dynamically to reduce battery power spikes.
In this case users can get a physical replacement of the battery (at a discounted rate of 29 from Apple until the end of 2018) or disable the limitation. To learn more about this, you can read this guide:
To disable this feature, select the link Disablecolored in blue. You may need to open your eyes wide, the text very small.
In cases where the battery is severely degraded, often when the maximum capacity falls below 80%, Apple will still allow users to disable performance management, but the probability of sudden shutdowns increases dramatically. The iPhone will show a further notice in Battery status which advises users to get help with their device. You can touch the link "More info …?To find out how to send your iPhone for assistance.
In some cases, the system may not be able to determine the status of the battery. The Battery Status screen will allow users to obtain a replacement battery, if this is the case.
iOS 11.3 no longer in beta, while the screen of Battery status still shows a label (Beta). It means that Apple will add more features to this screen in future versions. For now, this is a good response to customer complaints and the inevitable court cases born because Apple has hidden iPhone battery performance limitations.