iPhone battery and performance (2024)

All rechargeable batteries are consumables that become less efficient as they chemically age.

As lithium-ion batteries chemically age, the amount of charge they can hold decreases, reducing the time it takes for a device to charge. This may be referred to as the battery's maximum capacity - a measure of battery capacity compared to when it was new. In addition, a battery's ability to deliver maximum instantaneous performance or "peak power" may decrease. For a phone to function properly, the electronics must be able to draw power directly from the battery. One property that affects this instantaneous power supply is the impedance of the battery. A high impedance battery may not be able to provide enough power to the system that needs it. The impedance of a battery can increase as a battery has a higher chemical age. The impedance of a battery will temporarily increase at a low state of charge and in a cold environment. In combination with a higher chemical age, the impedance increase will be greater. These are battery chemistry characteristics common to all lithium-ion batteries in the industry.

When current is drawn from a battery with a higher impedance, the battery voltage will drop more. Electronic components require a minimum voltage to function properly. This includes the internal storage of the device, the power circuit and the battery itself. The power management system determines the battery's ability to provide this power and regulates the loads to maintain operation. When operations can no longer be supported with the full capabilities of the power management system, the system will perform a shutdown to preserve these electronic components. While this shutdown is intentional from the device's perspective, it may be unexpected to the user.

With a low battery state of charge, higher chemical age or colder temperatures, users are more likely to experience unexpected outages. In extreme cases, shutdowns can become more frequent, making the device unreliable or unusable. For iPhone 6, iPhone 6 Plus, iPhone 6s, iPhone 6s Plus, iPhone SE (1st generation), iPhone 7, and iPhone 7 Plus, iOS dynamically manages performance spikes to prevent unexpected device shutdowns so that iPhone can still be used . used. This performance management feature is specific to iPhone and does not apply to other Apple products. As of iOS 12.1, the iPhone 8, iPhone 8 Plus, and iPhone X include this feature; iPhone XS, iPhone XS Max, and iPhone XR include this feature starting with iOS 13.1.Learn more about performance management on iPhone 11 and later. The effects of performance management on these newer models may be less noticeable due to their more advanced hardware and software designs.

This performance management works by looking at a combination of device temperature, battery state of charge, and battery impedance. Only when these variables require it, iOS dynamically controls the maximum performance of some system components, such as the CPU and GPU, to prevent unexpected outages. As a result, the workload of devices will self-balance, allowing for a more even distribution of system tasks rather than large, rapid performance spikes all at once. In some cases, a user may not notice any differences in the day-to-day performance of the device. The level of change observed depends on how much performance management is required for a particular device.

In cases requiring more extreme forms of this performance management, the user may notice effects such as:

• Longer app launch times
• Lower frame rates while scrolling
• Dim backlight (this can be overridden in Control Center)
• Decrease the speaker volume by up to -3 dB
• Gradual reductions in frame rate in some apps
• In the most extreme cases, the camera's flash will be disabled as visible in the camera's user interface
• Apps that update in the background may need to be reloaded on startup

Many important areas are not affected by this performance management feature. Some of these are:

• Mobile call quality and network throughput performance
• Recorded photo and video quality
• GPS performance
• Location accuracy
• Sensors such as gyroscope, accelerometer, barometer
• Apple Pay

For low battery and colder temperatures, performance management changes are temporary. If a device's battery has been sufficiently chemically aged, performance management changes may take longer. This is because all rechargeable batteries are consumables and have a limited lifespan that will eventually need to be replaced. If you are affected by this and would like to improve the performance of your device, replacing your device's battery may help.

iOS 11.3 and later improves this performance management feature by periodically assessing the level of performance management required to avoid unexpected outages. If the battery health can support the perceived peak load, the amount of performance management will be reduced. If another unexpected outage occurs, performance management increases. This review is ongoing, enabling more adaptive performance management.

iPhone 8 and later use a more advanced hardware and software design that provides a more accurate estimate of both power consumption and battery capacity to maximize overall system performance. This provides another performance management system that allows iOS to more accurately anticipate and prevent an unexpected shutdown. As a result, the effects of performance management may be less noticeable on iPhone 8 and later. Over time, the rechargeable batteries in all iPhone models will decline in capacity and peak performance and will eventually need to be replaced.

For iPhone 6 and later, iOS 11.3 and later adds new features to show battery status and recommend if you need to replace the battery. You can find them in Settings > Battery > Battery health (with iOS 16.1 or later, you can find them in Settings > Battery > Battery health & charging).

In addition, you can see if the performance management feature, which dynamically controls maximum performance to prevent unexpected shutdowns, is enabled and you can choose to disable it. This feature is only activated after a device shuts down unexpectedly for the first time with a battery that has a reduced capacity to deliver maximum power immediately. This feature applies to iPhone 6, iPhone6 ​​Plus, iPhone 6s, iPhone 6sPlus, iPhone SE (1st generation), iPhone 7 and iPhone 7 Plus. As of iOS 12.1, iPhone 8, iPhone 8 Plus, and iPhone X include this feature; iPhone XS, iPhone XS Max, and iPhone XR include this feature starting with iOS 13.1.Learn more about performance management on iPhone 11 and later. The effects of performance management on these newer models may be less noticeable due to their more advanced hardware and software designs.

Devices updating from iOS 11.2.6 or earlier initially have performance management disabled; it is reactivated if the device then shuts down unexpectedly.

All iPhone models include performance management as standard to ensure that the battery and overall system are working as designed and that internal components are protected. This includes hot or cold temperature behavior, as well as internal voltage management. This type of performance management is required for security and expected functionality and cannot be disabled.

The maximum capacity of your battery

As the health of your battery deteriorates, so does its ability to deliver peak performance. The Battery Health screen includes a Peak Performance Capability section where the following messages may appear.

Performance is normal

Performance management applied

Battery condition unknown

Performance management is disabled

Battery health has deteriorated

Important message about the battery

If your device's performance has been affected by an old battery and you want help replacing the battery,contact Apple supportfor service options.

Learn more about battery service and recycling.

iOS 14.5 and later includes an update where the battery health reporting system recalibrates the maximum battery capacity and maximum performance on iPhone 11, iPhone 11 Pro, and iPhone 11 Pro Max to address inaccurate battery health reporting estimates for some users.

Learn moreabout battery health recalibration in iOS 14.5.