Do iOS updates wear out your iPhone's battery? The answer is not so obvious

Every iOS update - big or small - generates a torrent of comments and complaints about battery degradation. But the real culprit is something else.
Written by Adrian Kingsley-Hughes, Senior Contributing Editor
Reviewed by Min Shin
Purple iPhone with a white MagSafe battery back on its back
Jason Cipriani/ZDNET

Apple really needs to change the way it displays battery wear in iOS, as the current method is causing confusion among iPhone owners. Each time there's an iOS release -- either a big one or a small security update -- both my social media and my inboxes become awash with people worrying about their iPhone's battery.

Also: Here's what Apple doesn't want you to know about your iPhone's battery

And the latest iOS 17 update has not been any different. In fact, based on the feedback I've received, it feels like this update could be the worst to date (or just more people are noticing, that's a possibility too)

Not sure what I mean? Let me bring you up to speed.

Grab your iPhone, tap on Settings, and head over to Battery and then Battery Health & Charging.

Here you'll find a Maximum Capacity number.

That number starts out at 100%, and slowly ticks down as you charge and discharge your iPhone.

The one number that has caused so much confusion among iPhone owners -- Maximum Capacity.

The one number that has caused so much confusion among iPhone owners -- Maximum Capacity.

Adrian Kingsley-Hughes/ZDNET

If you want to geek out about what this number means or know more about your battery, I've written about that in detail.

The misconceptions

What I want to do here is clear up some misconceptions surrounding this number.

1. This is just one measure of battery wear

Maximum Capacity number is not a measure of overall battery wear. Instead, it is "a measure of battery capacity relative to when it was new." Put that another way, it's how much power the battery can hold.

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The lower the capacity, the less usage you're going to get between charges.

But it's a poor measure of the health of the battery. I've seen batteries die while this number is in the 90% range, and I've also seen iPhones plod on with this number down in the 70% zone.

2. iOS updates aren't causing battery wear

Updates don't wear your battery. What does is the normal charging and discharging of the battery as part of using the iPhone, subjecting the battery to overheating, and, far less commonly, using poor quality chargers and cables.

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Doing things like keeping your iPhone on charge all the time or never letting it fully charge can also sometimes cause the Maximum Capacity figure to display an erroneous value, and I've also seen it jump about following an update. But this isn't causing wear. Instead, it's causing iOS to display an incorrect number.

3. Hitting 80% is not death for your battery

I think this is a common misconception that arises from Apple's own documentation.

Apple has published information about recharge cycles and how they affect batteries, and here it says that the iPhone's battery "is designed to retain up to 80% of its original capacity at 500 complete charge cycles."

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I think that this gives the impression that the battery is dead at that point.

While the battery is undoubtedly worn, if you got 10 hours out of a charge when the iPhone was new, you're now getting eight hours. This might not be a problem for you, and the battery might give you many months of use.

So, what's the problem here?

There are two problems at play here.

1. The Maximum Capacity percentage is pointless

I get that Apple was perhaps trying to be helpful here, or maybe just filling space on a screen in the Settings app. 

Also: Battery bad after installing iOS 17? Try these 7 tips

Either way, this is just a single number and not a measure of general battery health. Apple would do better to eliminate this number and replace it with something more meaningful, like recharge cycles. Apple could also come up with a better way to portray battery health.

2. Maximum Capacity is highlighting a problem with modern iPhones

iPhones need a lot of recharging. Gone are the days of getting days out of a charge.

Or, to turn that on its head, batteries are too small for the demand we are putting on them.

If you're pretty much fully discharging your iPhone daily, then 500 recharge cycles are going to take you around a year and four months. If you're using about 50% of your battery's capacity daily, then 500 charges are going to take you about three years.

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What I'm seeing, both in my usage and in the usage of others, is that there are a lot of people who are barely making it through a day on a single charge, and as such, are going through those 500 recharge cycles within two years.

The solutions

There are three solutions to this -- use your iPhone less, Apple needs to equip it with a bigger battery, or battery replacements need to become a part of iPhone ownership (and Android smartphone ownership, because the batteries in those devices wear in the same way).

That's it. 

You can't, despite the endless stream of blog posts and YouTube videos, keep your battery's Maximum Capacity figure at 100% no matter what you do. Even if you keep it in its box in the drawer. 

Eventually, that battery is going to wear.

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The best solution would be for Apple to engineer a battery that's easy for owners to replace -- you know, like gadgets used to have. Until we get that, battery wear is going to continue to be an issue and owners are going to have to have to replace it or buy a new handset.

Because one thing's for sure: You can't change the laws of physics.

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