Right after updating my brand new iPhone 16 to iOS 26, the battery started draining really fast. Before the update, it was fine, but now it loses power quickly even with light use. I can’t use it for long periods without charging. Please fix this issue — it’s a brand new device and shouldn’t have this kind of battery problem.
iPhone 16, iOS 26
iPhone 16 Battery Draining Fast After Updating to iOS 26
As iOS26 was a major iOS upgrade,
seems much re-indexing etc., was going on in the background afterwards, in order to complete the update process. Memory and storage space could be in use for quite some time after installation, although we were able
to make use of our iPhones. Seems wise to keep iPhone well-charged during the first few days after installation.
If you haven't already: you may want to update your iPhone to iOS 26.0.1.
About iOS 26 Updates - Apple Support
Eg: says:
"iOS 26.0.1 : This update provides important bug fixes and security updates for your iPhone, including fixes for the following issues:
... and there's more info. in the above linked article:
iPhone 16 Battery Draining Fast After Updating to iOS 26
