Winter weather is part of life here in Canada, but some winters are colder than others. February 2015 was the coldest month that many parts of Ontario and Quebec have felt in a really long time, with Extreme Cold warnings becoming almost business as usual.
One effect of cold weather is poor battery performance – it’s possible for your iPhone to suddenly die despite reporting 30% battery life left. So why is it that your iPhone battery dies in cold weather?
Winter weather can be beautiful, but a dead iPhone is a sad thing
The iPhone battery
All iPhones use a type of battery called Lithium-Ion (sometimes abbreviated Li-ion). This is the most common battery technology found in rechargeable devices.
Li-ion batteries carry certain advantages – they charge fairly quickly and don’t need to be completely depleted before recharging (in fact, it’s better to recharge at 20% than waiting for your phone to die). Unfortunately, these batteries don’t do so well when the temperature outside drops.
Lithium-Ion batteries suffer in extreme cold temperatures:
According to Battery University, cold temperature “increases the internal resistance and diminishes the capacity” of a Li-ion battery. Specifically, they estimate that at -18 degrees Celsius a Li-ion may only deliver 50% of its capacity.
During last winter’s Polar Vortex, Global News did an experiment showing that an iPhone left outside dropped 14% in only 30 minutes, while an identical phone left inside dropped only 1%.
Apple specifies that their batteries work best at a range of 0 degrees Celsius to 35 degrees Celsius. While we almost never reach the upper range in Canada, temperatures below freezing are typical for the winter months.
Because the battery meter is calibrated for warmer temperatures, the reduced capacity in the cold can cause the reading to be unreliable. This is one of the reasons your phone may die while still showing 30%.
Keep your phone alive as long as possible
To keep your phone working as long as possible while it’s cold outside, the best thing you can do is to keep it warm. Avoid exposing it to the cold air unless absolutely necessary. This means keep it in a warm pocket – your hands will thank you too (it’s too cold to be walking and texting anyway!)
A case may help the phone retain some heat as well, just like a coat keeps you warm in the cold weather.
If all else fails, you may want to bring an external charger with you when it’s extra cold just in case your phone unexpectedly dies on you.
We suggest checking out the Anker PowerCore, which can add over 14 hours of battery life to your iPhone.
Update: January, 2016:
If it’s more than just cold weather…
It’s no secret that your phone’s short battery life might be the result of something more than bad weather (we created an ultimate guide on iPhone battery problems and how to fix them). Apple has gone so far as to launch a battery replacement program for the iPhone 5.
This is why we focus so much of our quality testing on battery life— every used iPhone has been tested to ensure a healthy battery. Check out our inventory here.
