Is It Bad to Leave Your Phone in the Sun?

Google Pixel 7
Joe Fedewa / How-To Geek

Metal and glass are good conductors of heat, and batteries can be dangerous if they get too hot. Leaving a phone out in the sun for extended periods will almost certainly lead to overheating.

A hat and sunscreen can protect you on a hot summer day, but the sun can damage more than just your skin. Your phone doesn’t have the option to slather on sunscreen, however, so let’s look at the risks of leaving your phone to bake in the hot sun.

Your Phone Is Designed to Release Heat, Not Absorb It

Smartphones are made up of all sorts of materials, but metal and glass are two of the most common. This is especially true of high-end phones, which usually opt for glass and metal over plastic. This can be a problem in the sunlight.

Metal is an excellent conductor of heat and quickly moves heat away from the internal components of the phone when your phone heats up under normal use conditions. Metal body phones are designed to work as heat sinks, absorbing the internal heat and helping it dissipate out of the phone—much like the heat sinks inside your computer move heat away from the CPU and GPU. When the only heat is from the phone itself, everything typically works as it should.

Heat from external sources like the sun changes the dynamic, though. The excess heat overwhelms your phone’s ability to effectively cool itself and the heat sink design is effectively reversed. The sun pumps heat into the components through the metal instead of the metal releasing the heat into the air. Plus, the glass used on a smartphone touchscreen is typically pretty thin. So, if your phone is lying face up in the sun, it’s going to get hot very quickly, and that can lead to display defects. There’s simply too much heat for your phone to deal with.

Regardless of what kind of your phone you have though—be it a chunky plastic budget phone or a sleek premium metal one—you want to avoid the excessive heat the sun pumps into the body of the phone.

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Excessive Heat Degrades Your Phone Battery

iPhone overheating

Let’s put some numbers to all this talk about heat. Just like computers and other electronics, a smartphone works best in a relatively cool environment.

Almost everywhere you look, you’ll find the ideal internal temperature for phones is between 32°F to 95°F (0°C to 35°C). Apple and Samsung both list this temperature range as the “normal operating conditions” for iPhones, iPads, and Samsung Galaxy devices. Apple also suggests storing devices where the temperature is between -20º and 45º C (-4º to 113º F).

The reason for these temperature ranges is battery degradation. The hotter a battery is, the harder it has to work to convert chemical energy into electricity. That in turn leads to decreased battery health—which you can check on iPhone and Android—and shorter battery life. Your phone has safeguards to protect against excessive heat from charging, but there’s only so much it can do to mitigate the heat from the sun.

Thankfully, most smartphones will alert you if temperatures get outside safe operating ranges. You’ll probably notice it yourself, too, if you touch the device. Anything over 99°F will feel warm to the touch. For example, if an iPhone gets too hot, you’ll see a big message on the screen that says, “iPhone needs to cool down before you can use it.”

RELATED: How to Check Battery Health on Android

Overheating Batteries Are Dangerous

Justin Duino / How-To Geek

A non-functional touchscreen is pretty problematic, and nobody wants to lose battery life, but there are worse things that can happen when you leave your phone to roast in the sun. The component in every smartphone that has the most potential for danger is the battery, and batteries and a hot battery is an unhappy—and potentially dangerous—battery.

Battery degradation is just one of the things that can happen with an overheated battery. Even worse is battery swelling and battery failure. When your phone can’t dissipate heat fast enough and the battery begins to catastrophically break down. Batteries move ions through an electrolyte substance, and as this substance decomposes through use, it generates gas that can build up and cause the battery to swell. Batteries in use are in a constant state of degradation, but normally the process is a slow bit-by-bit erosion of battery life and doesn’t pose a danger to anyone.

But high temperatures from the sun accelerate the process, which can lead to gases building up more quickly. A noticeably swollen battery is much more susceptible to tearing and combustion. Battery integrity is not something to take lightly. You’re much more likely to only experience shorter battery life than a flaming phone, but it’s important to know the worst-case scenario.

RELATED: 9 Smartphone Battery Myths You Should Stop Believing

Don’t Cool It Off Too Quickly

If your iPhone or Android device does get too hot, you might be tempted to cool it off quickly in the refrigerator, freezer, or even pop it in your cooler at the beach. That seems like a fast way to solve the overheating problem, but you want to avoid trying to “chill” your phone rapidly.

The big temperature change from being out in the sun to quickly cooling down can create condensation inside the device. Water inside your phone is obviously not good—but don’t reach for rice to fix it—the cold temperature itself can also be bad.

Just like batteries don’t like hot temperatures, they also aren’t fond of cold temperatures. As mentioned above, the ideal temperature for electronics is 32°F to 95°F (0°C to 35°C). While we’re talking about phone operating temperatures, it’s worth noting that extreme heat is the real thing to watch out for. In extremely cold temperatures, your phone will behave erratically and the battery will, temporarily, incorrectly report the battery life. But upon warming back up to room temperature, everything should be fine as long as moisture hasn’t condensed inside the device.

When dealing with an overheated phone that has sat too long in the sun the best course of action is to simply power it off and move it to the shade or somewhere cooler like the counter in your air-conditioned home. Let the phone cool down slowly on a cool surface. Don’t rush it or you’ll replace the overheating problem with another problem.

RELATED: Stop Putting Your Phone in Rice

While it’s probably fine to leave your phone in the sun for a few minutes, you shouldn’t let it cook in the sun for an extended period of time. Heat is generally not great for electronics, and smartphones are no different. Keep your phone in a bag under your chair or somewhere else shaded from the sun. The phone will be right there when you need it and you’ll avoid the intense heat of the sun shaving life off your phone battery.

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