Moses Johnson

You should always let your iPhone battery reach zero before you charge it up. Charging your iPhone overnight is bad for it, and you should always charge on airplane mode.

Be honest, how many of those claims have you heard? Better still, how many have you believed?

Well, not surprising, there are a lot of claims out there regarding the charging of iPhone batteries, but how many of them are true?

That’s what I’m going to try and find out in this article. I’m going to look at 10 common claims regarding the charging of iPhone batteries and find out whether they’re true or false.

Read through to the end of the article. I reckon there’s going to be at least one claim in here that you can officially stop worrying about.

Let’s get into it.

—

1. Charging your phone overnight isn’t good for it

This is a bit of a classic, really, isn’t it?

I think we’ve all heard this at one point or another, this idea that we should only ever be charging our phone when we’re able to keep an eye on it and remove it from charge the second that it’s full, for fear of it somehow overloading.

Quite simply, any quality modern device like a smartphone, or a tablet, or a laptop, or a smart watch is not going to overcharge, even if you leave it on the charger overnight.

Your iPhone has the smarts to know when your battery is full, and it will essentially stop charging at that point. And if the battery depletes sufficiently enough while the phone is still on the charger, it will then charge again to top it up.

In fact, if you’ve recently picked up your iPhone in the middle of the night whilst it’s charging, you might notice that it now uses optimized charging.

This is where the phone will immediately begin charging when you plug it in. But if it knows that you’ve got it plugged in overnight, and if the phone knows that your routine is usually to sleep until, say, 7am, the phone will only charge to around 80% initially and then finish off charging much closer to your waking up time.

This not only means that your phone is full and ready to go in the morning, it means that rather than blasting the battery with a full, high-speed charge very quickly, it can charge it much more gradually, which is better for the battery’s overall health.

If you want to see whether you’ve got this feature enabled on your iPhone, head to Settings > Battery Health & Charging and ensure that Optimized Battery Charging is enabled.

Notice here that you can also see the current maximum capacity or chemical health of your battery.

—

2. You shouldn’t charge your phone under your pillow

This is true, but not necessarily for the reason that you might expect.

Let’s put concerns about your phone with all its radioactivity being that close to your head overnight to one side for a moment.

The process of recharging a phone battery generates heat. Not enough heat to set fire to your bedding—if that’s happening, you’ve got a faulty phone or battery—but heat nevertheless.

Heat is the number one enemy of modern lithium-ion batteries and can cause severe permanent damage to it.

This is the main reason why you should never leave your iPhone sitting out in the hot sun, and why your iPhone will warn you if it begins to reach a dangerous temperature level. And whilst it might not reach those same temperatures when charging under your pillow, prolonged exposure to that kind of temperature is really not good for the battery at all and is a guaranteed way to reduce its lifespan.

To be fair, extreme heat isn’t good for any part of your phone, so leaving your phone out in the sun is just something you should avoid at all costs.

If you’re charging your phone overnight, do so in a place where it’s got plenty of room for airflow. Sitting on your bedside table or a charging pad should be more than sufficient, and don’t cover it with anything.

If the screen lighting up is an issue for you, either change the phone settings to have it not disturb you, or just sit it with the screen facing down rather than up.

—

3. The cable you’re using doesn’t matter

This isn’t true.

Technically, any cable with the right connector can charge your phone, but just because something can do something doesn’t mean that it should.

You wouldn’t apply the same logic to your brake pads for your car or windows for your house.

There are certain products where you really need them to be up to a certain standard, even if it means paying a little bit more.

This doesn’t mean that you have to buy official Apple cables, by the way.

Apple do charge a premium, but you should also avoid the absolute bargain-basement cables unless they’re coming from a reputable manufacturer or retailer.

You need to know that the cable you’re using is MFI certified.

MFI stands for Made for iPhone, and it’s an Apple licensing program that covers all manner of iPhone peripherals.

An MFI certified product will be allowed to display the badge on their packaging, and when it comes to a charging cable, it means that the cable can pass power to your phone correctly without risk of it overcharging.

MFI cables aren’t expensive in the grand scheme of things, so whilst it can be tempting to go for the absolute cheapest cables that you can, I’d advise you not to.

—

4. You should fully discharge your battery each time before charging

The need for fully discharging your battery is another popular battery myth and simply isn’t the case these days, thanks to the type of battery that phones use.

There are lots of different types of batteries out there. Some, like nickel-cadmium batteries, for example, should be nearly completely discharged before charging them up again, while lead-acid batteries should never be fully discharged.

Thankfully, lithium-ion batteries—the type found in modern phones—are much more forgiving and built for the kind of charging and discharging patterns you’d expect from a regular consumer.

So long as you’re following the other battery advice, things like not allowing them to overheat, and using certified cables and chargers with them, you can charge your phone fully overnight if you like, or you can plug in for 10 minutes for a quick top-up right before you go out, or a combination of all these things.

It really doesn’t matter. The battery on your phone has been built to work around you, and not the other way around.

—

5. You should charge using airplane mode

This one isn’t true, but it’s also not false as such.

The belief here is that charging on airplane mode will allow you to charge your phone much faster than charging it in regular mode, and this isn’t entirely false.

Airplane mode essentially shuts down all of the wireless communication features of your device—so no wi-fi, no cellular connection. As your phone is typically constantly looking to create and maintain wi-fi and cellular connections whilst it’s powered on, this will reduce some of the power usage of the phone.

The charge coming into the phone isn’t any more powerful. It’s just that the incoming power isn’t being offset by power usage as much.

But if you really want to charge your phone up more quickly, say in an emergency, a much more effective way to do this would be to power off your phone and charge it with the power off.

Because even in airplane mode, your phone is still using power—power for the screen, power for any apps that might be running, or apps you have running in the background.

An analogy would be filling a bucket of water that has a number of holes. If airplane mode plugs one of those holes, the bucket will fill up faster. But if there are still some other holes, you’re still going to lose water.

It’s only by plugging all the holes that you’ll be able to really take advantage of all of the water you’re pouring in, and that’s kind of the case with your phone and charging it.

But even then, it’s generally considered that with a good fast charger, unless you’re power using your phone at the same time that you’re charging it, you should be able to quickly charge your phone up without the need to put it into airplane mode.

Keep in mind, airplane mode basically renders the phone element of your phone useless, and you have to question whether it’s worth it just to slightly speed up your charging.

If it is, power the phone off, give it a rapid charge, then power it back on.

—

6. Batteries have a memory

This is kind of the same belief as the idea that batteries must always be fully discharged.

It just isn’t true with modern lithium-ion batteries.

Where some people get mistaken is mixing up battery memory with battery health.

You can find out your battery health by going into your iPhone Settings, choosing Battery, and then Battery Health & Charging.

My iPhone 15 Pro Max, purchased about seven months ago, still has 100% battery health, which is excellent. But if I was leaving this out in the sun all day, perhaps using dodgy cables with it, that figure could have dropped.

If this was, say, 80%, that just means that I’ve got 80% battery capacity to play with compared to the 100% that I had when it was new.

So, if a new battery would give me 10 hours of constant use—purely for illustrative purposes—then I would expect to get only eight hours off of a full charge when I’ve got 80% capacity.

But this aging process is, unfortunately, entirely normal.

Apple allude to it here when they talk about your iPhone battery chemically aging.

Your battery has a limited number of charge cycles in it before it can’t charge anymore, which is why, if you have a particularly old iPhone, you’re going to notice that it isn’t lasting as long as it did when you first got it, no matter how careful you might have been with regard to charging it.

When you reach this point, the best thing you can do is swap out your phone. A brand new phone will, of course, have a brand new battery. Or, if that’s not an option for you, a battery swap would also be a good solution, and there are companies out there that can help you with this.

—

7. You should use low power mode all the time

This is another myth that is more of an opinion than an absolutely factual answer. But I’m going to call this one false—you don’t need to use low power mode all the time.

Low power mode is exactly what it sounds like. It will switch your phone into a mode where it impacts a number of the power-hungry features of your phone.

According to Apple themselves, this includes 5G data, auto-lock, display brightness, display refresh rate, some visual effects, iCloud photos, automatic downloads, email fetch, and background app refresh.

You might be perfectly fine with some of these being disabled, but many of these features are what makes the iPhone experience so good, so it would be a shame to routinely switch them all off.

I guess the comparison would be buying a Porsche but installing a limiter that stops it from going over 20 miles an hour.

Low power mode is designed to eke out the last bit of power that your phone has, which is why Apple will suggest you switch it on once your phone reaches 20% or 10% power.

It’s there to help keep your phone running for just that little bit longer until you can get it plugged in to charge.

Also, keep in mind that once you reach 80% charge, low power mode will automatically switch off, so you can see that from Apple’s perspective, this isn’t a feature they expect you to have on all the time.

—

8. You can save battery by closing apps

This is another myth; quite the opposite is generally true.

The theory behind this is that phones that have apps running in the background are having to dedicate battery to those apps. So if you have 10 or 20 apps running in the background, that’s 10 or 20 lots of power from your battery that’s being dedicated to running apps that you’re not actively using. So closing them down would save you some battery life.

The reality is that your iPhone is built for multitasking, and in general, it’s very good at putting those background apps into a low-power, near-idle state.

Essentially, those apps aren’t running in the same way that the app you’re currently using is, but when you swipe on your phone to move from an active app to a background app, your phone has that background app in a state that makes it very easy for it to spring to life.

For you, the user, the experience feels like all of the apps are constantly running, so the fact that they aren’t is irrelevant to you.

This is actually one of those myths where the opposite is true.

Opening up apps is the thing that requires the most power usage, so constantly closing your apps down and then opening them up again can use more of your battery life, not less.

Think of it like an oven or a kettle. In general, it takes more electricity to heat your oven up or boil a kettle of water than it does to simply maintain a high temperature.

A professional kitchen will heat up their oven and then hold it at that temperature for the duration of the shift because it doesn’t make energy-efficient sense to keep powering something on, waiting for it to heat up, powering it off, and then repeating the process.

So yeah, use your apps as you wish. Your phone’s built-in multitasking smarts have got you covered.

You can force quit an app if something goes wrong with it, but other than that, you’re good.

—

9. You shouldn’t use your phone while it’s charging

This is kind of a myth.

The truth element of this comes from the fact that when your phone is charging—especially if it’s fast charging—that fast charge is putting some stress on the phone and the battery.

If you use your phone while it’s plugged in, most phones will automatically default to a low-power charge mode to allow the phone to continue drawing the power it needs to do what you want it to do while it’s charging.

You’re absolutely fine to use your phone while it’s charging. You’re not going to be putting yourself at any risk, nor are you damaging your battery.

The only real consequence you’re going to face is that your battery isn’t going to charge as quickly as it might if you simply plug it in, leave it alone, and allow it to fast charge.

But ultimately, you’re the consumer—it’s your phone, and you should use it how you wish. So I really wouldn’t worry too much about this.

—

10. Fast charging kills your battery

Again, another myth.

Fast charging has gone from being a kind of “oh, by the way, we have fast charging” feature a few years ago to a major, significant, almost dealbreaker feature of modern smartphones—and for good reason.

The latest iPhones are essentially insanely powerful computers that you carry around with you in your pocket, and with each year, their capabilities become even more impressive.

Consumers would be more than happy with more powerful, longer-lasting batteries provided that doesn’t equal a thicker phone. And while battery tech is improving all the time, an area where manufacturers have realized they can make improvements and increase consumer satisfaction is charge time.

If you can get to the point where a battery can be fully charged from 0% to 80% in only 10 minutes, battery capacity suddenly isn’t so much of an issue.

You could power use your phone all day long, then plug in for a quick charge while you have a coffee.

Plus, the charge on your iPhone isn’t that fast, certainly not compared with what some other phone manufacturers are doing right now.

The iPhone 15 Pro Max can charge at up to 27 watts with a compatible charger, and tests have shown that a Pro Max phone can charge from empty to full in around 90 minutes at this speed. Which is quick, but when you consider that there are phones like the Vivo IQ 7 which features 120-watt charging and can go from empty to full in 18 minutes, you realize that Apple is moving along carefully with this.

Apple sells millions of iPhones, and it really isn’t in their interest at all to sell phones where the battery seriously degrades each time you charge it.

Part of the technology behind this is the same kind of technology that stops phones from overcharging.

With fast charging, your iPhone will automatically receive a charge in different phases.

The first phase of the charge is the higher voltage phase, charging your battery from anywhere from 50% to 80% capacity very quickly, which does generate some extra heat and put some stress on the battery.

But for the remaining part of the charge, your phone will switch to a slower trickle charge phase, massively reducing the stress on the battery for that part of the charge, keeping the charge process both safe and healthy for your battery.

It’s why you’ll often see a notification informing you of exactly how long you’ve got left in your current charge cycle and what time the iPhone will be fully charged by.

Your phone is smart enough to be able to calculate exactly how long the charge is going to take.

So fast charge away, and as and when Apple releases even faster-charging iPhones, you can be pretty confident that they will have done their homework prior to launching the phones.

---

So there you go, 10 claims about battery charging with my thoughts on whether or not there’s something you need to worry about.

I think the main takeaway throughout all of this is that ultimately you’re the consumer—it’s your phone, and you should use it how you like.

Phone manufacturers like Apple know this, and they build their devices around your usage habits.

They don’t expect you to significantly change what you do to work for them.

Use your phone how and when you want to use it, charge it how and when you want to charge it, and trust that your phone is smart enough to be able to take care of itself.

---

What about you? How often do you charge your phone? Or are there any battery charging myths or tips that I’ve not included here?

Drop me a comment and let’s talk about it.