Last month, Apple said it had identified a “very small number” of iPhone 6s handsets built between September and October 2015 that could abruptly power off during use. Devices in the affected serial number range can be taken to an Apple Store or Apple Authorized Service Provider for a free battery replacement.
Apple has now elaborated on what caused the issues. In doing so, it has also explained why so few handsets were affected. The company said that components used while building the battery packs had been exposed to ambient air in the factory for longer than usual. This caused the batteries created in the substandard conditions to degrade faster than usual, most likely due to a chemical imbalance in the cells.
“We found that a small number of 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,” said Apple in a statement. “As a result, these batteries degrade faster than a normal battery and cause unexpected shutdowns to occur. It’s important to note, this is not a safety issue.”
The increased rate of cell degradation causes the phones to detect faults with the battery and automatically power off. Apple advised customers that it designs the iPhone to shut itself down when outside of its usual operating conditions. The company said that a sudden shutdown could be caused by variations in voltage or even temperature. It may not always be down to a defective battery.
Apple has insisted that the widely reported problems with the iPhone 6s’ batteries are “not a safety issue.” It appears to be concerned the replacement program could be likened to Samsung’s recall and subsequent discontinuation of its Galaxy Note 7 earlier this year. According to Apple, the impact of the manufacturing issue is limited to a reduced capacity and occasional unexpected shutdowns. There are no wider consequences.
“We looked for any other factors that could cause an iPhone to shut down unexpectedly,” said Apple. “After intensive investigations, no new factors have been identified. We will continue to monitor and analyze customer reports.”
iPhone 6s owners can check if their phone is affected by visiting Apple’s serial number validation tool. Handsets should then be taken to an Apple Store or approved third-party repairer for a free replacement battery pack. Apple is also offering to reimburse customers who have previously paid for a battery replacement. The program is valid worldwide for three years pass the original sale date of the phones.
