Cold weather is brutal on batteries, and the reason comes down to chemistry. Here is why your phone dies at 30 percent and your car groans on frosty mornings.
Cold Slows the Chemistry
Batteries make power through chemical reactions, and cold slows those reactions. Engineers explain that a lithium-ion phone battery cannot deliver its full charge when freezing, so the phone shuts off though energy remains. Warm it up and the missing percentage often returns.
Your Phone Is Lying to You
That sudden drop from 40 percent to dead is the phone protecting itself. Engineers say the battery management system cuts power when voltage sags in the cold. Keeping the phone in an inside pocket instead of a bag can prevent the shutdown.
Car Batteries Suffer More
Lead-acid car batteries lose about a third of their cranking power at freezing, automotive experts say, while the engine needs more power to turn thick cold oil. AAA says most car batteries last three to five years, and the first hard freeze exposes the weak ones.
How to Protect Both
Auto experts recommend having your car battery tested before winter and cleaning corrosion off the terminals. For phones, avoid charging in freezing temperatures and never leave devices in a cold car overnight. A little prevention beats a dead battery.
Sources: AAA, Battery University