Does Charging Your Phone To 100% Ruin Your Battery? Here’s The Truth.

Many of us are in the habit of plugging our phones in to charge overnight so we start each day at 100%. However, you might not be doing yourself ― or your battery ― any favors in the long run.

You might have heard that charging your cell phone battery and leaving it plugged in once it hits a full charge is bad for long-term battery life. According to Chao-Yang Wang, the director of the Electrochemical Engine Center at Penn State University, there is some truth behind this thought. Over time, “a battery will degrade faster if you charge it to 100% versus a little bit lower state of charge,” Wang said.

Keeping your phone plugged in once it hits a full charge and consistently charging it to 100% keeps the battery at a high voltage, which causes chemical aging in the product, said Dibakar Datta, an associate professor of mechanical and industrial engineering at New Jersey Institute of Technology.

Wang noted that if you frequently charge your phone to 100%, your battery will deteriorate roughly 10% to 15% faster over your phone’s lifetime than if you charged it to consistently to a lower percentage like 90%. “So it’s not a whole lot, but it’s noticeable,” he added.

Overall, this deterioration is slow, and phone batteries now are pretty durable, so you don’t need to be too worried. “[Batteries] last, probably, longer than the other features of the phone,” Wang said. You likely will need a new phone for other reasons, such as camera quality or a broken screen, before you need one for battery issues.

While charging your phone to 100% consistently isn’t great for the battery, this doesn’t mean you can never give it a full charge.

“This all depends on people’s needs and also convenience,” Wang explained. “If you do have a mission-critical day, you will be better off to charge to 100% so you have more electricity and longer usage time.”

Say you have a big travel day and need your phone for directions. You can certainly make sure it’s fully charged before heading out. But if you’re at home for the day and don’t need to rely on your phone, charging to 85% or 90% can help bolster the battery over the long haul, Wang added.

Datta said that it’s also not a good idea to drop your battery to 0% regularly and that instead, you should plug it in once it hits about 20%. Allowing your phone battery to frequently drop to 0% can harm your phone’s ability to hold a charge.

Keeping your phone charged between 20% to 80% tends to be the sweet spot, Datta added.

“I think that the battery is probably more afraid of too cold or too hot [temperatures],” Wang said. “I think that damage under those extreme conditions probably is greater than charging to 100% under normal temperatures.”

In most cases, smartphones are designed to change their charging rate when in different climates, Wang noted. This explains that too-hot-to-charge notification that appears on smartphone screens from time to time. “If you’re consistently getting too hot [notifications], then you need to be aware and pay some attention to the battery usage,” Wang added.

Ideally, your phone should be in room temperature environments whenever possible, Datta said.

It’s natural to be tempted by fast chargers. Who doesn’t want access to their phone more quickly? But experts say they shouldn’t be used too often.

“Slow charging is more preferable,” Datta explained. “Because when you charge very fast, it actually generates some heat in the battery, and when you generate heat in the battery, it can also degrade the battery over time.”

Having a battery that gets too hot can be dangerous, too. Phones have caught fire multiple times because of an overheated battery, Datta said. So, safety is a factor here, too.

If you are concerned about your phone’s battery, most smartphones let you check your battery health in battery settings. Or you can go to an expert at a store like Apple or Samsung, for example, to check your battery health. If your battery health is below 80%, Datta recommends replacing it.

All in all, there’s plenty you can do to keep your phone battery healthy throughout your device’s lifetime ― and most of the ways are pretty easy to follow.