iPhone battery and performance

Understand iPhone performance and its relation to your battery.

Your iPhone is designed to be simple and easy to use. This is only possible through a combination of advanced technologies and sophisticated engineering. One important technology area is battery and performance. Batteries are a complex technology, and a number of variables contribute to battery performance and related iPhone performance. All rechargeable batteries are consumables and have a limited lifespan – eventually their capacity and performance decline such that they need to be replaced. Find out more about iPhone batteries and how battery ageing can affect iPhone performance.

About lithium-ion batteries

iPhone batteries use lithium-ion technology. Compared with older generations of battery technology, lithium-ion batteries charge faster, last longer and have a higher power density, giving more battery life in a lighter package. Rechargeable lithium-ion technology currently provides the best technology for your device. Find out more about lithium-ion batteries.

How to maximise battery performance

'Battery life' is the amount of time a device runs before it needs to be recharged. 'Battery lifespan' is the amount of time a battery lasts until it needs to be replaced. One factor affecting battery life and lifespan is the mix of things you do with your device. No matter how you use your device, there are ways to help. A battery’s lifespan is related to its 'chemical age', which is more than just the passage of time. It includes different factors, such as the number of charge cycles and how it was cared for. Follow these tips to maximise battery performance and help extend battery lifespan. For example, keep your iPhone half-charged when it's stored for the long term. Also avoid charging or leaving iPhone in hot environments, including direct sun exposure, for extended periods of time.

When batteries chemically age

All rechargeable batteries are consumable components that become less effective as they chemically age.

As lithium-ion batteries chemically age, the amount of charge they can hold diminishes, resulting in shorter amounts of time before a device needs to be recharged. This can be referred to as the battery’s maximum capacity – the measure of battery capacity relative to when it was new. In addition, a battery's ability to deliver maximum instantaneous performance, or "peak power", might decrease. For a phone to function properly, the electronics must be able to draw upon instantaneous power from the battery. One attribute that affects this instantaneous power delivery is the battery’s impedance. A battery with a high impedance might be unable to provide sufficient power to the system that needs it. A battery's impedance can increase if a battery has a higher chemical age. A battery’s impedance will temporarily increase at a low state of charge and in a cold temperature environment. When coupled with a higher chemical age, the impedance increase will be more significant. These are characteristics of battery chemistry that are common to all lithium-ion batteries in the industry.

When power is pulled from a battery with a higher level of impedance, the battery’s voltage will drop to a greater degree. Electronic components require a minimum voltage to properly operate. This includes the device’s internal storage, power circuits and the battery itself. The power management system determines the capability of the battery to supply this power and manages the loads to maintain operations. When the 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 perspective, it might be unexpected by the user.

Preventing unexpected shutdowns

You're more likely to experience unexpected shutdowns when your battery has a low state of charge, a higher chemical age or when you're in colder temperatures. In extreme cases, shutdowns can occur more frequently, 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 peaks to prevent the device from unexpectedly shutting down, so you can still use your iPhone. This performance-management feature is specific to iPhone and doesn't apply to any other Apple products. Starting with 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. Find out about performance management on iPhone 11 and later.

iPhone performance management works by looking at a combination of the device temperature, battery state of charge and battery impedance. Only if these variables require it, iOS will dynamically manage the maximum performance of some system components, such as the CPU and GPU, in order to prevent unexpected shutdowns. As a result, the device workloads will self-balance, allowing a smoother distribution of system tasks, rather than larger, quick spikes of performance all at once. In some cases, you might not notice any differences in device performance. The level of perceived change depends on how much performance management is required for your device.

In cases that require more extreme performance management, you might notice effects such as:

• Longer app launch times

• Lower frame rates while scrolling

• Backlight dimming (which can be overridden in Control Centre)

• Lower speaker volume by up to -3 dB

• Gradual frame-rate reductions in some apps

• During the most extreme cases, the camera flash will be disabled as visible in the camera UI

• Apps refreshing in the background might require reloading upon launch

Many key areas aren't affected by this performance-management feature. Some of these include:

• Mobile call quality and networking throughput performance

• Captured photo and video quality

• GPS performance

• Location accuracy

• Sensors like gyroscope, accelerometer, barometer

• Apple Pay

For a low battery state of charge and colder temperatures, performance-management changes are temporary. If a device battery has chemically aged far enough, performance-management changes might be more lasting. This is because all rechargeable batteries are consumables and have a limited lifespan, eventually needing to be replaced. If you are impacted by this and would like to improve your device performance, replacing your device battery can help.

For iOS 11.3 and later

iOS 11.3 and later improve performance management 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, performance management will increase. This assessment is ongoing, allowing more adaptive performance management.

iPhone 8 and later use an advanced hardware and software design that provides a more accurate estimation of both power needs and the battery's power capability to maximise overall system performance. This allows iOS to anticipate and avoid an unexpected shutdown more precisely. As a result, the effects of performance management might be less noticeable on iPhone 8 and later. Over time, the rechargeable batteries in all iPhone models will diminish in their capacity and peak performance and will eventually need to be replaced.

Your battery's maximum capacity

The Battery Health screen includes information on maximum battery capacity and peak performance capability.

Maximum battery capacity measures the device battery capacity in relation to when it was new. A battery will have lower capacity as the battery chemically ages, which might result in fewer hours of usage between charges. Depending upon the length of time between when the iPhone was made and when it's activated, your battery capacity might show as slightly less than 100 per cent.

Batteries of iPhone 14 models and earlier are designed to retain 80 per cent of their original capacity at 500 complete charge cycles under ideal conditions.* Batteries of iPhone 15 models are designed to retain 80 per cent of their original capacity at 1000 complete charge cycles under ideal conditions.* With all models, the exact capacity percentage depends on how the devices are regularly used and charged. The one-year warranty (two-year warranty in Türkiye) includes service cover for a defective battery in addition to rights provided under local consumer laws. If it is out of warranty, Apple offers battery service for a charge. Find out more about charge cycles.

As your battery health degrades, so can its ability to deliver peak performance. The Battery Health screen includes a section for Peak Performance Capability where the following messages might appear.

Getting further assistance

If your device performance has been affected by an aged battery and you would like to get help with a battery replacement, contact Apple Support for service options.

Find out more about battery service and recycling.

Recalibration of battery health reporting on iPhone 11, iPhone 11 Pro and iPhone 11 Pro Max

iOS 14.5 and later include an update to address inaccurate estimates of battery health reporting for some users. The battery health reporting system will recalibrate maximum battery capacity and peak performance capability on iPhone 11, iPhone 11 Pro and iPhone 11 Pro Max.

Learn more about recalibration of battery health reporting in iOS 14.5.