Bloomberg News Experts say many users of older iPhones would be better off getting new batteriesApple Inc., facing questions from users and tech analysts about reduced performance in older iPhones, acknowledged Wednesday that its latest software curtails the computing power of some models to prevent unexpected shutdowns. It was a rare statement from the company that shed light on how Apple internally dealt with a growing user complaint. The statement came two days after John Poole, founder of the computer-performance testing group Geekbench, wrote a blog post illustrating how iPhone computing performance slows as battery health declines on iPhone 6s and iPhone 7 devices. Apple AAPL, -0.11% said that as iPhone batteries age, or in certain conditions such as cold weather or at low charge, they can struggle to respond to a phone’s power demands. This can cause the device to unexpectedly shut down to protect “its electronic components,” the company said. To prevent iPhone 6, iPhone 6s and SE devices from powering off — something that drew complaints last year from Chinese consumer-protection groups — Apple said it tweaked its iPhone operating system, iOS, to slow certain tasks that required more computing power than the device could provide. An expanded version of this report appears on WSJ.com.