Newer software, ageing hardware

If your iPhone’s battery seems to be vanishing faster than usual after installing iOS 27, Apple says there is a simple reason that your phone may still be busy working on the update even after the installation appears to be complete.

Apple’s latest support guidance says users who notice reduced battery life after an update should “wait a few days and then check again”. A major iOS upgrade can trigger background activity such as indexing data and files, downloading assets, updating apps and completing other system tasks, all of which can temporarily affect battery life and thermal performance.