Facing complaints from users, Apple has admitted that the latest iteration of its iOS operating system restricts the computing power of some iPhone models in order to cut the risk of unexpected shutdowns.
The Wall Street Journal said the admission was a rare statement that showed how the company managed a growing complaint internally.
Apple's statement came two days after Geekbench founder John Poole wrote a post about iPhone performance as a function of battery age.
"While we expect battery capacity to decrease as batteries age, we expect processor performance to stay the same," Poole wrote. "However, users with older iPhones with lower-than-expected Geekbench 4 scores have reported that replacing the battery increases their score (as well as the performance of the phone). What’s going on here?"
{loadposition sam08}Apple's statement said that as iPhone batteries get older, or in cold weather or at low charge, they could not manage the power demands of the device. This could result in the iPhone shutting down to protect its electronic components.
In order to prevent iPhone 6, 6s and SE devices from powering off - there were complaints about this in China last year - Apple said it had changed iOS to curtail the speed of certain tasks that needed more power than the device could provide.
"Our goal is to deliver the best experience for customers, which includes overall performance and prolonging the life of their devices," Apple said.
"Lithium-ion batteries become less capable of supplying peak current demands when in cold conditions, have a low battery charge or as they age over time, which can result in the device unexpectedly shutting down to protect its electronic components.
"Last year we released a feature for iPhone 6, iPhone 6s and iPhone SE to smooth out the instantaneous peaks only when needed to prevent the device from unexpectedly shutting down during these conditions.
"We’ve now extended that feature to iPhone 7 with iOS 11.2, and plan to add support for other products in the future."