Battery and charging
Peak Performance Capability
Most people call this whether the phone is slowing itself down to avoid shutdowns.
This line tells you whether your battery can still supply power fast enough, or whether the phone is limiting performance to stop unexpected shutdowns.
This setting is present on your iPhone.
- We have this path on file but have not yet confirmed it against an official source.
Where to find it - iOS 18 and later
- Settings
- Battery
- Battery Health
- Peak Performance Capability
What it does
A worn battery can fail to deliver a sudden burst of power, which makes the phone switch off even though it shows charge remaining. After that happens, performance management may be applied so peaks are smoothed out.
When management is active you can turn it off, but the shutdowns can return.
What changes
When it is on
The phone caps how hard it pushes the processor when the battery cannot keep up. Apps launch and scroll a little slower, and the phone stays on.
When it is off
Full performance returns, along with the risk of the phone shutting down without warning.
Should you turn it on?
Good reasons to turn it on
- Unexpected shutdowns are worse than a small slowdown.
- It lets an ageing phone stay usable until you can replace the battery.
Good reasons to turn it off
- You want full speed and can live with occasional shutdowns.
- You are replacing the battery shortly anyway.
Battery
No real change
Privacy
No real change
Performance
Depends how you use it
Cellular data
No real change
Storage
No real change
Out of the box: Not applied until the phone experiences an unexpected shutdown.
Worth reading first
Where this setting used to live
Apple moves settings between releases. This is every location we have on file.
-
iOS 18 and later
Settings > Battery > Battery Health > Peak Performance Capability
-
iOS 16 to iOS 17
Settings > Battery > Battery Health & Charging > Peak Performance Capability
Questions people actually ask
- Is Apple slowing down my old iPhone?
- Only after a battery has failed to deliver a power peak and caused a shutdown, and the screen tells you when that has happened.
If it is not working
- The option to disable management only appears after management has actually been applied.
- A new battery clears the condition entirely.