iPhone 6 Plus on ice
Photo provided by Paul Bodnar

Hiking Tip: What To Do When Your Phone Battery Gets Too Cold

Your battery indicator doesn’t always tell you the truth. We have noticed a lot of confusion about how low temperature affects your phone’s battery life, so we decided to run an experiment and check it out. When hiking, here is what you should do if your phone battery gets too cold…

Long-distance backpackers experience a wide range of temperature. Which means that if you carry a phone, your phone also experiences a wide range of temperature. We have noticed a lot of confusion about how low temperature affects your phone’s battery life, so we decided to run an experiment and check it out.

But first, what is the acceptable operating temperature range? Apple recommends a range of 32º to 95ºF (0º to 35ºC) for the iPhone and Google recommends the same for its Android Pixel 2. You should always turn your phone off if you expect you are going to be outside this temperature range.

Battery level of a cold phone

We ran an experiment on an iPhone 6+ to see what happens to battery level when your phone is cold. Here is what we did:

  1. Put an 85% charged iPhone in a 36ºF / 2ºC refrigerator for 11 hours with power ON
  2. After 11 hours the battery level is 27%
  3. Warm the phone to room temperature and the battery level is still 27%
  4. Restart the phone and the battery level is 71%*

*The temperature discrepancy appears to be a bug in the iPhone 6+, which has since been corrected in newer models of the iPhone, i.e. when newer iPhones warm up, the battery level is reported correctly rather than staying at it’s cold-temperature level.

These results are as expected — a battery works with a chemical reaction, and chemical reactions slow down when it’s cold. So your phone is tricked into thinking there is less battery capacity, when in reality, the stored energy has not changed (read this for a full explanation).

iPhone Fridge
iPhone 6 Plus cooled down to 36 degrees Fahrenheit in a refrigerator.

Recommendations

  • Turn your phone off if the temperature is higher than 95F/35C or lower than 32F/0C
  • If your phone is cold and you need to use it, warm it up in your pocket before you use it so that you know the true battery life.