With Apple’s little-known feature, dubbed Power Reserve, it’s possible to locate a misplaced iPhone and use certain other features for hours after the battery dies.
- The Find My app on iOS 15 supports finding iPhones in Power Reserve mode
- iOS puts your iPhone in Power Reserve mode when the battery hits 0%
- You can locate an iPhone this way for up to 5 hours after the battery dies
Using Find My to locate a lost iPhone in Power Reserve mode
It used to be that when the iPhone battery dies, you had to plug the phone into power to recharge the battery before using it again. With a feature called Power Reserve, certain functions continue to be available even if iOS isn’t running because the device needs to be recharged. Read: How to turn on battery percentage on iPhone 13
With iOS 15.2 and later, you can put your iPhone into this mode on the slide-to-power-off screen. The device automatically enters this mode after the battery is depleted. Power Reserve doesn’t kick in when the user initiates a manual shutdown.
Apple acknowledges in the iOS 15.2 release notes that the software update brings the ability for Apple’s Find My app to locate a lost or misplaced iPhone for up to five hours when in Power Reserve mode.
Power Reserve, digital keys and Express Card transactions
This feature requires an iPhone model that supports Ultra Wideband networking, meaning any iPhone from iPhone 11 onward. Provided you have the required hardware and software, turning on the Find My network shall allow you to locate a misplaced device for up to five hours when in Power Reserve mode, or up to 24 hours after it’s turned off.
In addition to Find My, the Power Reserve feature is used in a few other places in iOS.
The ability to unlock and start a compatible car with digital keys may be available for up to five hours when the iPhone battery needs charging. The same applies to using digital keys for your home or hotel room stored in the Wallet app. With Power Reserve mode, those keys work even if the iPhone battery runs low.
Finally, those who use digital transit cards can use a payment or transit card designated as the Express Transit card for up to five hours after the battery dies, provided there’s still enough power in the battery to support Express Card transactions.
All iPhones from iPhone XR/Xs onward support Express Cards and Power Reserve.