PSA: What to do if you leave your phone in the cold

It’s happened to all of us: you accidentally left your smartphone in the car. Sometimes you might rush back to get it, and other times you might think, “Hey, I don’t need it now. I’ll get it when I’m back.”

Typically, a cold phone sitting in a vehicle for a few hours is not too big of a deal, but when the temperature outside is below freezing, it could cause unexpected problems for your phone’s battery. The biggest problem is a quick drain — depending on how cold it is, a smartphone battery could go from fully charged to completely dead in minutes.

What’s worse is that it will be impossible to recharge the device right after that quick drain. But don’t worry! Your battery is probably OK, and your smartphone is most likely going to be OK. Read on for tips on what to do if you face these issues, and then continue reading further to learn about why this happens. Also, keep in mind that the same principles apply to pretty much any device with a lithium-ion battery, including laptops, tablets, portable game systems, etc.

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Don’t try to charge your cold phone

Robert Triggs / Android Authority

If your phone isn’t working, or isn’t turning on, chances are you won’t be able to charge it either. This is because the battery’s capabilities to recharge may be affected by extremely cold temperatures. We’ll talk more about this later in the post.

For now, you’ll have to get it to normal temperatures before it starts working again. During this warming process, do not charge your cold phone. Just let it warm up on its own with no charging cable attached.

Try to keep the phone off for some time

Edgar Cervantes / Android Authority

Condensation is another thing you should consider. This is especially the case if you leave your phone in a humid place. Some of that humidity might leak inside the phone in non-liquid form. Not only that, but an operating phone naturally warms up. Bringing the phone to normal temperatures will liquify said humidity, and your phone might be prone to water damage.

If you, say, dropped the phone in the snow and picked it up later, your best bet is not to take any chances and let the cold phone dry before you turn it on. You might even be able to see some moisture under the screen, or inside the ports. We have a list of tips for fixing water-damaged phones. Those steps will work while trying to get your cold, wet phone dry.

Get the phone back to room temperature

Dhruv Bhutani / Android Authority

Now it’s time to get to work. You need to get that freezing phone back to average temperatures. This could be as simple as bringing the phone inside and just letting it sit for a few hours while it naturally gets back to a regular state.

If you can’t wait that long, you can very carefully heat the device by placing it near a warm surface. This could be putting it into your pocket, laying it near (but not on) a radiator, or leaving it on your car’s dash while the heater pushes hot air.

Be careful, though: you should never put the phone in an oven or a microwave, and you should never place it on or near something incredibly hot such as an electric hot plate or stove. You want the device to get a little warm, not cooked. Additionally, you want the phone to warm up slowly.

Also: The best touchscreen gloves to use with your phone

Extreme temperature changes can make parts crack, especially screens. The screen isn’t the only part you should worry about, though. Internals are also cold, and those parts cracking can mean a much bigger problem.

Please turn it on once the phone warms up and you know it’s dry. The battery might be at the same level it would have been before it got so cold. If it’s not, feel free to plug it in and charge it up as usual.

Why does the cold drain the battery?

Ryan Haines / Android Authority

Interestingly, scientists don’t quite understand why this happens. The science is clear that incredibly cold temperatures drain lithium-ion batteries very quickly, but the reasons why are still somewhat mysterious. We know that lithium-ion batteries rely on chemical reactions to charge, hold that charge, and then release that charge, and the cold slows these reactions.

Each smartphone battery has two sections: the anode and the cathode. When the battery is fully charged, lithium ions are embedded in porous graphite located in the anode, and when it’s drained, the ions are on the opposite end in the cathode. Electricity is produced when individual lithium-ions flow from the anode to the cathode.

For some reason, when lithium-ion batteries are placed in cold temperatures, the chemical reaction produced by the movement of the lithium ions slows to a crawl — or even stops altogether. The smartphone senses that the battery no longer produces a charge and drops the charge meter to 1% or even 0%. If enough time passes, the phone will shut off.

Next: These are the best Android phones with the best battery life

If you try to charge the phone while it’s in this state, the reactions still won’t happen because the battery is still too cold. In fact, this new introduction of electric current could cause problems for the battery.

Only when the battery is brought to a warmer temperature will the lithium ions move as usual. Then everything will once again work as expected. This is why a cold battery can go from empty to full again just by warming up: the lithium ions (i.e., the amount of battery charge) didn’t fully move from one end of the battery to the other; they just stopped moving.

Keep this in mind next time you are in a cold place! Try to keep your smartphone warm.

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