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This Is What’s Killing Your Batteries

An iPhone with low battery indicator, no plugged in

There are few things more frustrating than a phone or laptop that won’t hold a charge. When a battery starts to fail, a gadget can become far less portable or, in some cases, completely useless. So what causes battery degradation, and what can we do about it?

Battery degradation is something we’re all familiar with, but it isn’t something that happens overnight. When you notice your phone isn’t holding a charge all day anymore—or that laptop that used to last hours isn’t making it past 30 minutes—it’s probably too late. You might not even blame the battery, instead pointing the finger at an app or pondering if you’ve been using the device a lot more.

You can, of course, switch a failing battery for a new one. But that can be expensive and impractical. Just under half of smartphone and tablet users, along with a third of laptop owners,  would instead get a new device than repair their old one. Other people make the best of it, which is why the laptop I’m writing this article on is plugged into the wall.

So if repairing or replacing a battery isn’t your thing, what can you do to get the most out of the one you have?

Not All Batteries are the Same

a pile of batteries, with one very different from the others

Several kinds of batteries are available, and each type has a different function. Your TV remote probably has a couple of alkaline or zinc-carbon batteries in it. These are cheap, disposable, and easy to replace. When you start your car in the morning, the chances are it’s a lead-acid battery that’s doing the work. These are expensive but durable and should last a few years—even under challenging conditions.

Then there’s the lithium-ion battery. Unlike an alkaline or lead-acid battery, which has been pretty much the same for decades, much focus has gone into developing and advancing lithium-ion batteries. Lithium-ion batteries are preferred because they are relatively light and can hold a lot of energy—which is why you’ll find them in cellphones, laptops, and portable gaming devices. They are also what this article will be focusing on.

Overcharging Is Bad

A phone on a wireless charging, showing 100% charge
Jevanto Productions/Shutterstock.com

Overcharging is probably the most dangerous thing you can do to a lithium-ion battery. In a worst-case scenario, they could catch fire or explode. Safety circuits prevent overcharging by stopping more power from going into a “full” battery. However, those safety circuits can fail. While those failures may not be catastrophic or common, they can still damage your phone.

A more significant issue is what happens when your phone spends a long time sitting with a full charge. Time spent at full capacity can corrode a lithium-ion battery, reducing its capacity and overall lifespan. The convenience of plugging your charger in before you go to sleep and waking up with a full battery comes with a cost.

However, Apple and Google have identified this problem and implemented a solution. Adaptive charging systems will note the times you tend to charge your phone. Then, armed with this information, your phone will charge itself to 80% before topping that charge up to 100% just before you are likely to wake up.

Adaptive charging tech is likely to become more common, but if you have an older phone or a new phone that lacks this feature—try to limit the time it spends plugged in.

Totally Draining Your Battery

Like overcharging, most companies put safeguards in place to stop you from draining a lithium-ion battery completely. A “full discharge” can severely and permanently damage your battery. On the plus side, if your phone says it is dead, it more than likely has a few percent of its battery life remaining.

However, a battery in storage will lose charge over time. Lithium-Ion batteries are better at holding on to their juice than most—but will still lose around 2% charge each month. That safety circuit that stops your battery from being overcharged will also drain about 3% of that battery’s charge each month.

So if a gadget is out of charge and you decide to throw it in a drawer for a few months, it might need an entirely new battery the next time you use it.

Excessive Temperatures

The back of a smartphone with a visibly swollen battery
Thongchai S/Shutterstock.com

The safe temperature range of a lithium-ion battery is between minus 4° Fahrenheit and 140° Fahrenheit (-20° Celsius to 60° Celsius). You do have to go beyond these ranges to kill your battery, but the more time spent outside the “safe zone,” the more performance damage your battery will suffer.

There are many ways your phone could find itself far above or below its ideal temperature. If you live in the northern US or Canada, there’s a good chance the place you live will drop below -4°F at some point during the year. And while the outside temperature doesn’t quite reach 140°F, a car can go far beyond both human and battery limits on a hot day.

Beyond nature, doing something as simple as pushing your phone or laptop to the limits as its charging can pump the battery temperature up. Equally, letting a laptop get dirty to a point where the fans can’t run properly or putting it on a surface covering its ventilation ports can spike the device’s temperature. Most devices will shut off when they heat to a certain point, but that won’t stop the sun baking your gadget, and it won’t cool the device off instantly.

Remember, the longer your battery spends outside its safe temperature range; the more damage will be done to that battery.

You Can’t Fight Time

An iPhone and a MacBook charging on a desk
Lee Charlie/Shutterstock.com

Although batteries lack moving parts, repeated usage will still make them wear out. Lithium-ion batteries typically last around 300-500 charging cycles.

However, a battery is unlikely to completely “break” at the end of its “lifespan.” You are likely to see a vastly decreased level of performance, which will only continue to worsen. Your battery won’t store as much energy, hold on to the energy that is in there, and pump out as much power as it used to. When it hits the point where it can’t power your device, the chances are it will still have some life in it—just not enough to do its job.

Make the Best of It

So, what can you do about it? The best option is simply managing your phone’s battery usage, so you have to recharge less often. On the plus side, you’ll run out of battery far less, and that battery will last a lot longer. That said, micromanaging your battery might be more of a pain than just replacing the dead battery or the whole device when it eventually degrades beyond any usefulness.

Make sure your device isn’t perpetually on the charger, and make sure it has a good amount of charge in it if you plan on storing that device for an extended period. Although charging your phone while you’re asleep is convenient, you could damage your device if it lacks adaptive charging. Fast charging capabilities are far more common and can fill your phone in no time at all. So getting into the habit of charging your phone for an hour in the evening, or topping it up when you wake up for work, may give your battery a longer life.

Regarding temperature, batteries can survive greater temperature extremes than most humans, so just keeping the device with you will solve a lot of problems. If that’s not possible, try and keep it indoors and be aware of how intensely you are using it—especially while charging.

You can protect your battery as much as possible, and it will fail. But by taking a few of these steps, you may get a lot more use out of it and the device it powers.

Dave McQuilling Dave McQuilling
Dave McQuilling has spent over 10 years writing about almost everything, but technology has always been one of his main interests. He has previously worked for newspapers, magazines, radio stations, websites, and television stations in both the US and Europe. Read Full Bio »