Apple has admitted the battery meters in the iPhone 6S and 6S Plus are unreliable and can display higher battery levels than they actually have.
The bug works by failing to update the battery percentage displayed, resulting in some phones shutting off when their batteries deplete, even though their battery meters still read fully or partially charged.
Apple says the bug is caused when users manually change the time or time zones on their iPhones, for example when travelling.
The tech giant says it is "aware of this issue and is investigating the cause and a solution."
Patches for iPhone bugs usually come with the next iteration of Apple's iOS software and Apple has not disclosed when its next software update will be available, although a beta version of iOS 9.3 was released on 11 January.
In the meantime, according to Apple, users experiencing battery meter problems should:
- Turn off and restart the phone
- Update settings to ensure date and time are programmed to set automatically
Apple iPhones by default use the Internet to automatically check and correct their displayed time, including changing time zones when necessary.
If iPhone users experience battery meter problems when they have not manually changed the time or time zone on their device, they should contact Apple Support.