If you’re caught outside—heaven forbid!—in this week’s polar vortex, an Arctic air spillover numbing North America, your phone might act peculiar. Indeed, you may notice the battery life of your handset take a hit. If you’re not careful, the charge could drop precipitously, without warning, from 30% to…well, zero.
It’s true: Cold weather worsens the performance of phone batteries. While this may seem mysterious, there’s a simple reason for the juice-sapping affliction. Here’s what’s behind the phenomenon and a few tips, mostly common sense, for keeping your devices alive.
Put simply, phone batteries worsen in the cold because of chemistry.
The rechargeable batteries in most modern consumer products, including cellphones, laptops, and electric vehicles, use Lithium ion technology. In these systems, an electrical current flows from a positively charged anode, typically made of graphite, to a negatively charged cathode, a metal oxide. In between, an electrolyte, usually a salty liquid or gel, conducts electricity.
Under normal conditions, charged particles flow seamlessly between opposing nodes, creating an electric current and source of power. But cold temperatures complicate the situation. Put a liquid in a freezer and it will freeze; a similar principle is at work inside a battery cell.
Cooling causes the electrolytic medium to thicken and become more viscous, explains Linda Nazar, a chemistry professor at the University of Waterloo in Canada. This makes the material a poorer conductor, reducing the mobility of the charged particles that drive the battery’s chemical engine.
“Batteries work on electrochemistry and those processes get slow when the temperature drops,” Nazar says. “That’s just a consequence of the laws of nature.”
What tech companies say
Most major phone-makers alert customers that frigid environments will affect their products’ performance.
Apple, maker of the iPhone, says that battery life decreases in colder temperatures, but notes that “this condition is temporary.” As the company’s website reassures, “Once the battery’s temperature returns to its normal operating range, its performance will return to normal as well,”
The “ideal comfort zone,” as Apple puts it, ranges from 62° Fahrenheit to 72°F. But iPhones should remain unaffected as long as they’re kept above the freezing point of water, as the Apple graphic below advises.
Screenshot from Apple’s website
On the other end of the spectrum, hot temperatures can “permanently damage battery capacity,” Apple warns. In other words, cook your phone and a charge will forever carry less juice.
Samsung seeks, meanwhile, to dispel what it calls a “common myth” persisting among some consumers: that batteries last longer if stored in a freezer. The company specifically advises against this practice, warning that it “is not correct and can damage your battery.”
Always be prepared
Now that you understand the science behind temperature and battery performance, here are our tips for you. To reiterate, yes, they’re mostly common sense.
—Keep your phone within the right temperature range. (Samsung, for instance, advises against stashing phones in the glove compartments of cars on very hot or cold days.)
—Bring a portable, external battery pack with you. They’re cheap, and they can come in handy in a pinch.
Now bundle up out there!