Multiple users on Apple's iPhone support forum are reporting big drops in battery life after upgrading their handsets to version 6.1 of the iOS operating system.
The messages, spread over several threads on the message board, all claim battery life of just a few hours after the new operating system is installed. Apple began offering iOS 6.1 to users on Jan. 29.
"I updated my iPhone 4 to iOS 6.1 from 5 (don't recall the full number) and after that the battery drained in 4 hours after a full night on the charger," a typical post said. Another said, "With 6.1, I can actually see battery going down [about] 3% every minute, this is insane."
The root of the problem is far from clear, but Mac blogs are centering on a theory that the OS ends up in an infinite loop with Exchange mail servers, causing the battery to drain fast.
Indeed, several users reported success with deleting or reinstalling accounts.
"The 'mail trick' works! I have exchange and iCloud accounts, deleted them both, rebooted after 5 minutes, added both accounts back (with push on both). 100% --> 94% within 4 hours," one said.
But others said a complete reinstall of the phone's iOS 6.1 resulted in improved battery life.
One user on Twitter posted an image of a message on his iPhone screen, apparently received from Vodafone UK, warning against the upgrade.
"If you've not already downloaded iOS 6.1 for your iPhone 4s, please hold off for the next version while Apple fixed 3G performance issues. Thanks."
Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is email@example.com