There are a lot of questions about mobile phone batteries. Should you leave your phone plugged in overnight? Is it bad for the phone? Is it even safe?
In fact, how much should you charge your phone? When’s the right time to plug in? Should you let it run down to zero every time? Should you charge it up to 100%? How do you get the longest life out of the battery inside a phone? Does it even matter, if you’re going to keep the handset around for just a couple of years and then upgrade?
Longer update pledges mean that battery health is a big deal for modern smartphones, and manufacturers are starting to take note. We already have features like Adaptive Charging, but Android 15 is expected to introduce an optional 80% charging limit in a bid to prolong battery lifespans. This will match a similar feature that Apple already debuted with the iPhone 15.
But doesn’t that number, 80%, seem rather arbitrary? Is there really any point in capping yourself at less than full capacity?
We present to you the myths and truths of iPhone or Android phone charging, in particular regarding whether you should plug you phone in overnight.
Charging My iPhone Overnight Overloads the Battery: False!
One thing all the experts agree on is that most devices are smart enough these days to avoid overloading themselves. Extra protective chips inside make sure that can’t happen in a tablet, a phone, or even alaptop. Once the internal lithium-ion battery hits 100% of its capacity, charging stops.
With older phones, if you leave you phone plugged in overnight, it is going to use a bit of energy by constantly trickling new juice to the battery every time it falls to 99%. That is;eating into your phone’s lifespan .Newer phones and OSes compensate for this; since iOS 13, Apple has shipped phones withOptimized Battery Charging ;turned on, so iPhones will usually not charge past 80% when connected to a charger for an extended period (like, say, overnight). With the latest iPhone 15, you can specifically tell the phone in settings to never go above 80% charge; if it’s on a charger, it won’t even try to recharge until it goes at least to 75%.
The Best Thing to Do
Don’t worry about this too much. Plug the phone in or place it on the wireless charger when you go to sleep. If you wake up in the night, unplug it or move it to prevent constant trickle-charging. You could also plug your phone into asmart plug;that’s on a schedule to turn off.And make sure that the Optimized Battery Charging option is turned on.
Potential Problems With Charging Phones Overnight
Trickle charges can generate some heat. Many experts recommend taking a phone out of the case to charge it overnight. But that’s not always feasible with a complicated protective case.
Battery health has two major arch nemesis: heat and voltage. The former can mostly be controlled by keeping your phone off a hot dashboard, not charging it under your pillow, and using slower charging when you don’t need a quick top-up. Voltage wear, however, can’t be controlled so easily by the user; voltage stress is simply a result of charging a battery.
At the very least, do not stack anything—books or other devices, for instance—on top of a charging device. And for the love of Jobs, do not put your phone under your pillow. Do any of the above, and you can expect the phone to get hot—not necessarily hot enough for spontaneous combustion but enough to damage the battery.
If you’re afraid of fire, some recommend leaving the charging device on a dish or saucer while it’s plugged in or placing it on something metal that is more likely to dissipate heat, the way a heatsink does on the chips inside a PC. That’s not much of an option if you use a wireless charging pad, so don’t sweat it.
I Should Freeze My Phone to Prevent Battery Problems: False!
Lithium-ion batteries hate two things: extreme cold and extreme heat. Repeatedly charging a phone in sub-freezing temps can create a permanent plating of metallic lithium on the battery anode, according to BatteryUniversity. You can’t fix that problem; it’s simply going to kill the battery faster.
Your phone battery is not alone in hating heat; all the internal components of a phone feel the same. Your phone is a computer, and computers and hot air are mortal enemies going back decades. Leave your black-screened phone sitting in the sun as you laze by the pool, but don’t be surprised when it throws a warning that it needs to cool off. Instead, give it some shade. In the summer, keep it off the car dashboard.
Apple specifically says charging iPhones in an environment that’s hotter than 95 degrees F (35 degrees C) does permanent damage to the battery. Expect the same with any modern phone.
The Best Thing(s) Never to Do
Don’t charge a phone when it’s too cold or hot. And don’t put your phone in the freezer.
My Battery Should Always Drop to Zero Power Before I Charge It: False!
Running a phone until it’s dead—a full discharge—is not the way to go with modern lithium-ion batteries. Try not to let it get close to 0%. That wears out a lithium-ion battery faster than normal. Partial discharge is the way to go.
Batteries are on borrowed time from the get-go. The insides are in a constant state of decay that can’t be helped. Over time, the materials inside are simply going to hold less and less power. If you’ve got an older iPhone still in use and wonder why it’s only got a charge for a few hours compared to the almost full day (or two) you got when it was new, that’s why. Capacity diminishes over time.
Drain a phone battery to zero only when you want to recalibrate the internal sensor that displays your phone’s battery level. Success here is hardly guaranteed—in fact, many people don’t think it works at all—but it’s recommended by some, especially with a phone that goes down to 10% (or even 20% or 30%), then abruptly dies.
Note that even when you do use the phone all the way to auto-shutdown, that may not mean the battery is actually at 0%. Leave the phone alone for a few hours, if you want to try recalibrating. Then give it a reset for good measure.
The Best Thing to Do:
Plug the phone in before it asks you to enter a low-power mode; iOS will ask you to turn that on when you hit 20% power. Plug the phone in when it’s between 30% and 40%. If you can’t turn on the Optimized Battery Charging, pull the plug at 80% to 90%; going to full 100% when using a high-voltage charger can put some strain on the battery.
Keep the phone’s battery charged between 30% and 80% to increase its lifespan. Eighty always seems to be the magic number when it comes to lithium-ion batteries.
Apple claims that with fast charging, iPhone batteries can increase 50% in only 30 minutes. That requires a USB-C power adapter, which on older phones in turn means using a special USB-C-to-Lightning cable or a higher-voltage charger such as the one from an iPad or even a MacBook.
Don’t fast-charge your phone if it doesn’t support it. That’s just another thing that’ll strain the battery. But it’s hard to find a phone these days that doesn’t support fast charging.
But,if you plan to swap out your phone every year or two, charge it any way you want for as often as you want, and don’t worry about diminished capacity. But if you want to stretch out your phone’s useful life, pay attention to best practices for lithium-ion batteries, as described above. Or you could just get a new battery installed every couple of years, which is much cheaper than a brand-new phone. Then hold out for 2028!
