Apple's battery cases can keep your iPhone running longer, though they do add quite a bit of bulk to the devices. They cost around $130 each, so you may want to take advantage of the program while you can: Apple says it will replace cases up to two years from their date of sale. If you can't go to an Apple Store or an authorized service provider yet, don't worry. While malfunctioning batteries may sound alarming, the tech giant says the program isn't related to a safety issue.