Apple has launched a battery replacement program for a "very small percentage" of iPhone 5 units. But that could mean hundreds of thousands of phones.
The afflicted iPhones have batteries that suddenly show much shorter battery life or need to be changed often, according to Apple. "The affected iPhone 5 devices were sold between September 2012 and January 2013 and fall within a limited serial number range," according to Apple.
Depending on how Apple defines "very small percentage," it could still mean tens, or even hundreds, of thousands of iPhones. That period is Apple's first fiscal 2013 quarter, and the company sold 47.8 million iPhones according to Statista (including some iPhone 4s, 3, and even 3g) for its second highest quarterly sales by units. If 1 percent were affected, that would mean nearly half-a million phones.
To be eligible for the free battery replacement, your iPhone must show the problems suddenly shorter battery life or frequent replacements and be in otherwise working order.
On Apple's battery support webpage, enter your phone's serial number to see if it falls into the range of affected models. (To find your phone's serial number, tap Settings > General > About and see the list of items, one of which is "serial number." Starting with iOS 6, tap and hold the serial number to show the "copy" option. Then use iOS copy/paste to enter the number in the field. Check here for more details.)
Affected users have three options for replacing the battery: Apple Authorized Service Provider, Apple Retail Store, and Apple Technical Support.
Before replacement, do the following: back up data to iTunes or iCloud; turn off "Find my iPhone;" and erase data and settings (Settings > General > Reset > Erase all Content and Settings).
Finally, if you think your iPhone 5 had a short-lived battery, and you already paid to replace it, you can contact Apple Support here about the possibility of a refund.