Apple is replacing the batteries in iPhone 6S models that randomly shut off

Only iPhone 6S phones made between September and October 2015 are included. Photo / Jason Oxenham

Is your iPhone 6S randomly shutting down? Apple may owe you a new battery.

The company said this week in a post on its website that some iPhone 6S owners are eligible for a free battery replacement because their phones unexpectedly cut their power even when they have enough charge.

Apple did not offer many details on why the phones are shutting down, except to say that the problem is "not a safety issue" and that it affects a "very small number" of phones.

A look at Apple's support forums suggests that people have been reporting similar problems since at least 2015; users said their phones shut off and could not be restarted until they were plugged in again.

The replacement program was announced shortly after a state-approved consumer-protection group in China - a key market for Apple - asked the iPhone maker to address reports that some phones shut off even when their indicators said the phones were charged more than halfway.

The Chinese Consumers Association said the issue affected the iPhone 6 and the iPhone 6S, the Wall Street Journal reported.

Only iPhone 6S phones made between September and October 2015 are included in the program. Smartphone owners who have been having this problem should take their phones to an Apple Store or authorized repair shops to get the official replacement.

And users should know: If there are other problems with the phone, such as a cracked screen, Apple will replace the battery free only if you fix (and pay for) those repairs first.

The company said other problems with the phone can make it harder to replace the battery.

If you have already had your battery replaced because of this problem, you can contact Apple's support team and ask for a refund.

Apple launched another replacement program last week after acknowledging that some of its iPhone 6 Plus models had what consumers have called "touch disease" - a long-standing issue in which an iPhone's screen becomes unresponsive. But Apple did not offer a free fix for that problem, which the company said is caused by users' dropping their phones repeatedly.

Apple is facing a lawsuit over the "touch disease" issue.