Is It Safe to Charge a Cell Phone Overnight?

No, your phone won't explode but there are a few things to know

Smartphone plugged in to charge


One of the questions people still have about their smartphones is about the battery. They wonder if charging a phone overnight will damage the battery, if they should let the battery drain completely before recharging it, and if it's safe to use right out of the box without a full charge. There are still a lot of myths about smartphone batteries out there, so here are some straight answers about it.

Every smartphone is different. If you're truly concerned about the way you charge your phone, your best option is to read the user's manual that came with it. Every manufacturer (including Samsung, Apple, Google, Motorola, and many others) provides specific instructions for charging your device to maintain the longest possible battery life.

Can You Charge Your Phone Overnight?

In short, yes, you can leave your phone plugged in overnight. Today's phones are smart enough to be left plugged in overnight without damaging the battery. They have extra protection on the chips and in the software that stop the charging process when the battery reaches 100 percent, even if it's still plugged in. Plug it in before you go to bed (or place it on the wireless charging pad) and forget about it. Your phone will be fine.

Your battery should last for as long as you have the smartphone. Barring a manufacturer's defect or other non-authorized care, your smartphone's battery should last you for as long as you have the phone, because phone batteries measure their lifespans in charge cycles, not years.

Battery Life and Charge Cycles

A charge cycle is when you discharge up to 100 percent of the capacity. For example, if your phone is at 70 percent, you use 30 percent (you're now at 40 percent) today, and you charge it back up to 70 percent tomorrow, then use 30 percent of the charge again tomorrow, that's one charge cycle. However you divide the 30 percent you use is up to you, but as soon as you charge that 30 percent back on the phone, that's a cycle.

The average smartphone battery today, brand new, has anywhere from 300-500 charge cycles available in it before the battery's performance starts to degrade. So, if you're charging it reasonably, you should have a nice long battery life to work with.

Should You Fully Charge a New Phone?

Despite dire warnings when cell phones were much less mature, you aren't required to charge your new smartphone right out of the box anymore. Your new smartphone is shipped with minimal juice in the battery, and using it up won't affect your battery life long-term.

The only reason some manufacturers suggest fully charging your phone before you use it is to make a good first impression. After all, by the time you get the phone, it might only have 10 or 15 percent battery and won't last long at all as you set it up and download apps. Manufacturers want to ensure you're getting what you paid for, which is a fully functioning smartphone right from the start. You can wait till it goes to zero as you set it up, or you can charge it up to 100 percent right out of the box. It's up to you.

The Best Time to Charge a Phone

Which brings up another point: your battery doesn't need to drop to zero percent before you recharge it. Early cell phones had nickel-cadmium batteries, which did perform better if you let them empty before recharging them.

Today's smartphones use lithium-ion batteries, which are okay to charge no matter the percentage of unused power left. Some experts say you should never let a lithium-ion battery drain entirely as it can wear out the battery faster than normal. So, charge your phone whenever you need to, the battery will be fine.

Manufacturers place limits on devices, chargers, and cords, so they don't charge the battery too quickly and damage it. You should always try to use the cord that came with your phone or an original replacement when charging your device to keep from damaging it.

Tips for Charging Your Phone

  • You can use your phone while it's charging: You can use your phone while it's charging, it just may take a little longer to charge completely. That's because instead of using the battery's charge to power whatever you're doing, it uses the electricity you're getting from the plug.
  • Your phone will charge faster if it's turned off: Turning off your phone when it's plugged in will charge it faster simply because nothing is using the battery or power. Apps that are open and still working in the background can slow down the charge. Individually, these apps don't use a lot of power, but when you have 10+ apps open, they'll suck the juice out of your battery faster. When your phone is off, it's not processing or checking anything, meaning all the electricity flowing from the charger can go to charging it.
  • Charging your phone through your computer or laptop won't damage the battery: It will usually take longer to charge your phone when it's connected to your computer because the speed of the charge depends on the cord and the type of USB port your computer has. Many still have USB 2.0 ports, so even with a USB 3.0 cord (lightning cable or otherwise), your phone will charge more slowly. If anything, charging your phone from your laptop is a little better than through an outlet, because it puts less strain on the lithium-ion battery (and its internal workings) as they accept the charge. Less strain means a happier battery.

Use the Right Chargers and Cords

Ideally, you should use the charging cord and plug that came with your phone. They're made according to the standards in place to charge your phone using the correct voltage. An off-brand charger or cord can damage the charger port in your phone and, by extension, the battery. If you must, you can use an approved cord or charger that has the stamp of approval from your phone's manufacturer. 

If you find yourself away from an acceptable charger and your battery is getting low, you can try a few tricks for making your battery last longer like turning off Bluetooth when you don't need it, lowering the screen brightness, closing any apps you're not using, or turning on airplane mode to conserve the battery. 

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