How to charge batteries so they last longer
There’s a darker aspect of gadget ownership: Lithium batteries are tricky. They’re all gradually losing capacity, meaning it’s only a matter of time before your device just doesn’t have enough juice to be useful. But how much time? Some of this is baked into the design – but how we charge and use batteries can also make a difference.
For example, keeping your device plugged in most of the time can save you the stress of being caught with a low battery. But it could also drain your battery.
So what can we do to make batteries last longer? I called two scientists working on lithium batteries, Gregory A. Keoleian at the University of Michigan and Michael G. Pecht at the University of Maryland. “The main drivers that influence degradation are temperature, state of charge and rate of charge,” says Keoleian.
They advised us to always follow manufacturers’ specific advice. (For the record, here’s what Apple and Samsung say.)
But the scientists also shared some useful general tips on how charging habits can help our batteries live long, happy lives.
1) Don’t charge until you’re down to 20 percent
To get the most out of your lithium battery, your goal is to slow the rate at which you go through so-called charge cycles. All devices are designed and manufactured with a certain number of times that the battery can be fully discharged and recharged. It is usually between 300 and 1,000.
So here’s a handy rule: Don’t start charging until your battery is about 20 percent — and try to stop when you’re about 80 percent. This ensures you’re maximizing each cycle while keeping the battery stress-free. (Read on to learn how some smart devices like iPhones do this for you.)
“It’s better to charge just before use — that’s ideal,” says Keoleian.
It’s also true that the slower you charge, the less damage the battery will take. Today, some products are sold with “fast” charging capabilities when using special bricks or car chargers. Fast is obviously great when you’re in a hurry, but Pecht says avoid it unless you need it.
2) Don’t leave it 100 percent plugged in — or let it go to zero
Many of us charge devices overnight while we sleep, which is fine. But then we also plug them in for the commute to work or at the desk all day. “Avoid leaving devices plugged in 24/7,” says Keoleian, as it can drain your battery.
Conversely, being completely drained drains your battery, so avoid draining your battery to zero if you can.
And forget a myth that says you occasionally have to fully discharge and recharge to clear the battery’s “memory”. That’s true of lead-acid batteries, but not the lithium batteries that most mobile devices use today.
Pecht recommends that devices that you do not use for a long time, e.g. B. an electric drill, with about 50 percent charge. That means it’s also not a good idea to leave things in their chargers if you won’t be using them for a while. (We’ll get to laptops in docking stations below.)
3) Don’t let it get too hot
Like most of us, our batteries are happiest at 72 degrees or cooler. And it’s particularly bad for battery chemistry to be exposed to heat above 30 degrees, such as on a muggy summer day in the car. “Remember, when a battery is enclosed in a case, it can get even hotter,” says Pecht.
Cooler temperatures (above freezing) aren’t so bad, although some manufacturers advise against charging in extreme cold. Pecht says he keeps unused batteries in the fridge — just make sure they’re not exposed to moisture, which could corrode the electronics surrounding the battery.
4) Don’t get too hung up on charging with a newer phone or laptop
Good news: Over the past decade, products including high-end smartphones and laptops have become much smarter when charging, automatically preventing some of the errors mentioned above.
Many laptops that can sit in docking stations for weeks now know to stop charging and keep the battery below 100 percent — though Keoleian says it’s still a good idea to unplug it every now and then.
Apple iPhones running iOS 13 or later have a nifty feature called Optimized Battery Charging that can track your typical routine and automatically time the charge to make sure it’s full before you wake up and need to use it.
5) Do not upgrade if the battery dies – fix it
When your device’s battery finally dies, you don’t necessarily have to dispose of it. Ask the manufacturer if there’s a way to replace the battery — or even see if you can do it yourself using a repair website like iFixit.
Using an existing device for a few more years saves you money and it’s a lot better for the environment too.