In most cases, the culprit behind an iPhone shutdown in the cold is the lithium-ion battery. In colder temperatures, ions lose their properties, causing an increase in internal resistance. Consequently, the battery’s capacity decreases, leading to unexpected shutdowns, even when there’s seemingly ample charge remaining.

This issue affects all iPhones, but older models, with batteries more worn due to the standard 500 charge cycles, tend to suffer more. As these batteries age, their capacity diminishes, impacting performance and making them susceptible to cold-related shutdowns.

Apple states that iPhones function optimally within a temperature range of 0 to 35°C. Operating below this range can result in performance degradation or rapid discharge leading to shutdowns.

What to do if your iPhone turns off and won’t turn on in the cold?