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Apple explains why some iPhone 6S models are randomly shutting down

After launching a battery replacement program for some iPhone 6S users on Thursday, Apple has now explained what caused the problem in the first place.

In a post on its Chinese support site, the company said those devices manufactured between September and October 2015 contained a battery component that was exposed to ambient air for too long.

The company also reaffirmed this was not a Note 7-like safety issue and told users that not all unsolicited shutdowns are indications of a problem. For example, an iPhone shutting itself off in extremely cold temperatures can be a self-protective measure.

The company is replacing the affected batteries free of charge and users can insert their serial number in order to check eligibility.

Related: iPhone 6S long-term review

The post (via Neowin) reads. “…iPhone 6s devices made in September and October 2015 contained a battery component that was exposed to controlled ambient air longer than it should have been before being assembled into battery packs.As a result, these batteries degrade faster than a normal battery and cause unexpected shutdowns.

“It’s important to note, this is not a safety issue.

“We also want our customers to know that an iPhone is actually designed to shut down automatically under certain conditions, such as extremely cold temperature. To an iPhone user, some of those shutdowns might seem unexpected, but they are designed to protect the device’s electronics from low voltage.”

The battery replacement program is the second such initiative introduced in the last few weeks.

However, whereas the battery replacements are free, devices affected by the Touch Disease flaw, which causes degradation of display sensitivity and, in some cases, screen flickering will be subject to a $149 charge.

This is because Apple believes the issue has, in part, been caused by users repeatedly dropping devices on hard surfaces.

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Have you been experiencing random iPhone 6S shutdowns? Share your experiences in the comments section below.