iPhone 13 battery drain and warmth after iOS 26 update

Martyn2605 wrote:

Prior to this downgrade battery health was 100%, now it isn't. Battery use shows that System Settings is responsible for 80% of the drain.

If your iPhone 13 showed a Battery Health of 100% a year and a half after it had been discontinued by Apple, that is usually a sign that the health had been artificially "boosted" and common when purchased from a third party. Another possibility is that you had replaced the battery and where that was done would be relevant. It simply is not possible an original battery on an iPhone 13 would be showing 100% Battery Health today without any unsupported manipulation in the Battery Controller.

The System Settings usage of your battery is indicative of the file indexing being performed in the background after the update. That will continue for about 4 days and also generate heat and some lag will be noted in the UI. That is seen here in the Apple Support Article:

About Apple software updates - Apple Support

You can continue to follow up with the requested screenshots if it has been longer than the 4 days (or maybe 6 in some cased depending on charging habits).

Martyn2605 wrote:

Well, I finally got to speak to a real live Apple Support person using a different phone (one that works). It passed the hardware tests that they sent so the diagnosis was that the update had failed.

The phone has now bricked.

That is actually good news, as a Hardware failure would likely cost you money for a repair and an update failure is restorable using a computer. That can be either a Mac or PC and you can even borrow a friends to do it. If you would like Apple to do that on one of their computers, yes it will require a trip to an Apple Store or any other Authorized Apple Service Provider.

• Restore your iPhone, iPad, or iPod to factory settings using a computer - Apple Support
• Genius Bar Reservation and Apple Support Options - Apple
• Find Locations

iOS version 26.0?

I assume you mean 26.4 since you mentioned a recent update, but if that is not what you have installed I would recommend to update. You can also post a screenshot of the Green battery graph and the top 5 apps consuming your battery from Settings > Battery > View All Battery Usage.

If background processing from the recent update is still being performed, you will see a message on the screen there that battery drain & heat will continue until that setup in the background has completed.

Martyn2605 wrote:

Prior to the 26.4 downgrade my iPhone 13's battery health was at 100% and a full charge would last for 3 days with my typical light use. Since the software change health has reduced to 85% and I have to charge every day.

The update does not change your Battery Health. Your iPhone 13 is expected to last 500 charge cycles before the health drops below 80% and need to be replaced. Not charging it overnight means that your battery is going to continue to be used to maintain power to the cellular/wifi antenna when you are not even using it and the background processes performed overnight will also be done under batter power. That results in an increase in Charge Cycles since 1 charge cycle occurs when the battery has consumed its full capacity, not how often it is charged.

Personally I recommend to use Optimized Charging and charge your phone all night, every night. Letting it go for several days, you are more likely to have the battery completely drain and if that happens multiple times you can expect the battery to be damaged.

To see what apps are consuming the battery, go to Settings > Battery > View All Battery Usage and post the top 5 apps. You will find some apps are updated frequently and you may not even know when that happens as the only indicator is a little blue dot next to its icon the first time it is launched after the update. Some of those app updates have been problematic. Instagram is one example where it has 15 updates over just the last month and the most recent one was yesterday. The battery usage of Instagram has been on a roller coaster across some of those updates.

You don't have to go to the Apple Store. Contact Support and ask them to run remote diagnostics on your phone.

You can also use the Support app on your iPhone. Check the App Store for that.

This may be frustrating though, because the results are very likely going to indicate that things are fine.

Please report on your results.

The iPhone 13 was discontinued in September 2024. Even if you bought one of the last phones off the line, the phone must have sat somewhere for almost a year before it was activated in August 2025.

That could not have been good for the battery, and it would not be surprising to see unusual battery performance numbers.

The iPhone 13 Battery settings do not show Cycle Count information, so you must be using some third party software to see those numbers.

If you did activate the phone in August 2025, the warranty should be good until August 2026. If the Battery Capacity drops under 80% in the first year of operation, Apple will normally replace the battery at no charge unless there are more details that we are not aware of.

Make an appointment at the Apple Store / Genius Bar or take the phone to an authorized Apple service shop. You can find a list of authorized shops in your area using this link:

Find Locations - AppleAppleFind Locations

Literally last night the same thing happened me the 13 was an older phone of mine get last night it completely went Haywayire If u have apple care on it it’s with it to go to the Apple Store and also Best Buy has apple genussis too just so u know

You have a hardware problem, not a software problem. Not sure when you purchased it from Apple, but it was sold between 2021 and 2024. Activation date is irrelevant and a phone that has been sitting and even powered off in a sealed box is going to completely discharge and damage the battery after years of non use. Lithium batteries need a nominal charge to prevent deterioration.

Check your AppleCare coverage in Settings. That will be helpful to determine your support options.

Find information about your warranty or AppleCare plan - Apple Support

Well, I finally got to speak to a real live Apple Support person using a different phone (one that works). It passed the hardware tests that they sent so the diagnosis was that the update had failed.

The phone has now bricked.

Since the phone has "bricked" and you don't want to spend a day taking it in for service, you can ship the phone in to Apple Service.

My prediction......there will be a charge for service / repairs / replacement, despite your "new" claims. I hope I am wrong about that though.

Prior to the 26.4 downgrade my iPhone 13's battery health was at 100% and a full charge would last for 3 days with my typical light use. Since the software change health has reduced to 85% and I have to charge every day.

The (hopeless) Support app reports nothing wrong.

It has been downgraded to 26.4. The phone overheated and needed to be connected to the mains for 48 hours. During this period it over-rode mobile data settings and burned a month's worth of data despite being connected to broadband via wifi for the whole time.

Seemingly the replies I post are not getting through.......

For about 2 days after the 26.4 downgrade the phone was 'hot' and needed to be recharged every 4 hours. During that period the mobile data settings were ignored and, despite being connected to wifi for most of that time, a month's worth of mobile data was consumed in a couple of days.

It was not bought from a third party. It was brand new, sealed box, from Apple but it was not activated until August 2025, ergo has been in light service for 6/7 months.

Following the latest round of random glitches the battery maximum capacity is reported as 80% and the cycle count as 43.

If the technician reports that the battery is normal, I don't think that we will be able to change that.

About how old is the iPhone 13? When was the last time that you replaced the battery?