Apple caught heat earlier this year when it was found to purposefully slow down iPhone 6, iPhone 6s and iPhone 6s Plus devices with older batteries. The company said the intention was to slow the phones to preserve aging batteries and prevent the devices from automatically restarting.
Cook explained Apple's thinking with ABCNews: "At the heart of any decision we make is the user, and we felt it would be better to take something off of the performance to prevent [iPhones from restarting] ... We deeply apologize for anybody who thinks we have some other kind of motivation," Cook said.
"We've listened to the feedback very carefully and in addition to giving everyone a very low price on a battery if they'd like to get a new battery, we're also going to, in a developer release that happens next month, give people the visibility of the health of their battery. It's very very transparent. This hasn't been done before. We will tell someone we're reducing your performance by some amount in order to not have an unexpected restart and, if you don't want it, you can turn it off."
Apple began offering $29 battery replacements in early January.