Eli Blumenthal

USA TODAY

Apple's iPhone 6S battery issue is larger than the company first thought.

The problem: iPhone 6S devices that shut down the phones abruptly. After announcing an exchange program last month for certain phones, Apple said Tuesday that the issue may extend beyond phones manufactured in September or October of 2015.

Apple to replace faulty batteries on some iPhone 6S models

"A small number of customers outside of the affected range have also reported an unexpected shutdown," wrote the iPhone maker in a posting on the company's Chinese support page.

Apple notes that some phones shut down "under normal conditions in order for the iPhone to protect its electronics," but that it would be releasing a software update next week to garner more information. It is also exploring a possible software fix that would be deployed in a future version of iOS.

The issue seems to be affecting iPhone 6S phones purchased around the world during that time period, with the company setting up a support page for users to check their serial numbers to see if their phone is one of the bad ones.

The company stresses that the issue poses no safety risk to users.

Apple declined to comment on how many phones are impacted or if the issue extended to other devices such as the iPhone 6S Plus.

The problem stems from a component in the battery that was "exposed to controlled ambient air" for a longer period of time than it should have been before it was put into the battery packs.

Those with iPhone 6S phones that they feel have been having issues can go to their local Apple Store or an authorized service provider, the small repair shops that say they're authorized by Apple as well as retailers such as Best Buy. If it is determined that your phone is one of the affected units, the company will swap out the battery free of charge, though those with other issues, such as cracked screens, will need to pay to have those problems fixed before the battery can be replaced.

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Apple is the latest major tech company to suffer from battery issues. Samsung notably recalled and canceled its Galaxy Note 7 phone this fall after numerous devices saw their batteries catch fire or explode. There have thus far been no reports of similar issues from the iPhone 6S.

Follow Eli Blumenthal on Twitter @eliblumenthal