For about two years, I have been meaning to get a new iPhone. The phone is almost five years old and the battery is absolute crap. I have to carry around a backup battery pack if I’m going to be away from a charger for more than, say, two hours, and I charge it at least twice a day – once overnight and again around 2 p.m. (if I haven’t been using it, of course). Two days ago, I woke up around 3:45 a.m. to use the restroom and had this thought out of nowhere, ”Oh, I should unplug my phone. I wonder if leaving it charging overnight isn’t helping with my battery situation.”

I must have been intuiting something, because later that morning, an article popped up in my inbox that talked about the effects of charging your phone to 100% and then leaving it charging before you’re ready to use it. According to research done by Penn State University, constantly charging your phone to 100% actually makes it “degrade faster.” Letting your phone get too hot is bad too.

Bad for battery life: 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.

A slow deterioration: 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.

Go on ahead and charge it to 100% if you need to: 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.

20-80% is that “sweet” spot: 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.

Temperature damage: “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.

A fast charger is a bad charger: 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.

Check your battery’s health: 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.

[From HuffPost]

Well, then…the more you know. I have always been a “plug it in and leave it” kinda gal, so I have no first-hand anecdotal experience about saving your battery by only charging it (in general) to 80%. Does anyone do that on the regular for the purpose of extending your battery’s life? Mr. Rosie infamously rarely charges his phone and although we got ours on the same day, for whatever it’s worth, his battery did last a solid year longer than mine did. My phone also tends to overheat when charging it in the car, so I guess I’m double-screwing it up.

Part of me still thinks that Apple secretly puts some sort of “self-destruct” coding in these batteries because they always seem to go right around the same time in their lifecycle. That said, I’ll give it a shot because why not? It’s definitely too late for my current battery, but I will totally try this 80% method with my next phone. Speaking of, I need to make sure I get a new one ASAP, before the new tariffs make it like $10,000 for an iPhone.

Photos credit: The Painted Square, Sini Leunen and Ketut Subiyanto on Pexels