iPhone battery draining after iOS 18 Update

It’s the photos app. I’ve had things like background app refresh, dictation and location turned off for years. I have about five (non Apple) apps installed (no social media or entertainment type) and I use my iPhone 15 Pro primarily for talk and text which never accounts for more than 5% of my battery use, even on a heavy use day. I went from holding a two day charge to charging twice a day immediately after iOS 18. I noticed in Battery Heath that Photos was using 32% of my battery in the background which was alarming because I don’t use Photos in that capacity, and for the fact that I have background refresh disabled. My solution was to turn cellular data off for Photos entirely. (Settings > Apps> Photos > Cellular Data> toggle off) It’s been about a week and my battery is holding almost the same charge it did pre-update. I hope this helps!

Apple has essentially overhauled the utility app into their own version of social media, riddled with unnecessary AI and it’s working as such. Imagine it as uploading 5,000+ photos and videos to Instagram all at the same time. As long as you connect to WiFi periodically, your photo’s will continue to sync to iCloud. I don’t use the app much, but I can’t find any reason to have Photos running on cellular.

Side note: I do not connect my iPhone to WiFi on a regular basis. If you are constantly connected to WiFi, this fix likely won’t work for you as the app will continue to run in the background via WiFi and there is currently no way to disable this function (hence the issue).

Here is what Apple says on it's battery support article about iPhone battery drains after updates.

If you notice that your battery life has decreased after updating your iPhone, wait a few days and then check again.

Even though you can use your iPhone immediately after an update, certain tasks related to the update continue in the background and might affect battery life and thermal performance.

Give it a day or so and then see if things improve on their own. Your iPhone is doing a lot of background work after an iOS upgrade, particularly such a significant one as this, and that can take quite a bit of battery power to complete. Check again tomorrow or perhaps Thursday and see what the situation is.

Regards.

Found fix! Had the same issue. Brand new iPhone 16 Pro with iOS 18. Battery was draining super fast while it was overheating at the same time. Charged all night and the phone had only 40% in the morning because it stopped charging due to overheating. Turned out, my calendar app was using more power than the entire phone and all the other apps combined. After I deleted the calendar app, my phone started working without overheating and lasted for almost 2 days with one full charge. Also, I noticed, there is no need to deleting the calendar app. Alternatively, you can just turn off iCloud sync for Calendar and that will also stop it from draining your battery. I hope they will fix that with the next update.

iOS 18.0.1 did not make a difference. The root reason of the drain (in my case) is that the Cellular Data section in Cellular Settings is refreshed every second, draining the battery and heating up the phone. The temporary workaround that worked for me was to run "Reset Network Settings". This will stop the update of the cellular data area, as well as the battery drain and heating issues. This only lasts a day, so I am doing it virtually every day when I notice the phone heating up. It is a difficult workaround until Apple issues a remedy.

The problem was an app called Miles. It is an app that tracks miles for points. It was in some type of runaway loop. I have had the app for years but the upgrade to 18 did something. Once I deleted the app, phone works great. Thanks to you tube and ChatGPT.

I've narrowed the problem down to my Exchange account. The statistics in Settings-Battery show it is actually the Calendar causing the drain. Then I found some very old forum threads suggesting that in the past, Exchange was the culprit in something like this. So I deleted my Exchange account (leaving the three other accounts) and the battery drain stopped completely. Once I re-added the Exchange account, I'm back to massive drain (50% in 6 hours without use). So it seems I can choose between using my work iPad (!) without my work email account, or not using it at all...

Update with partial fix: If Cellular Data statistics are refreshing once a second, there is at least one app causing this. For me, it was the mobile game LOTR: Rise to War. Disabling cellular data access for that app has mostly resolved the issue. There may be other apps which cause the same problem as it has occurred once since I took this step. However, it was definitely LOTR RTW, as opening that app with cell service enabled for it immediately causes the issue to occur when the app is in the background.

You’ll know it’s happening because the phone gets warm almost immediately.

Steps to fix:

1. Close all apps
2. Restart phone
3. Settings -> Cellular -> Cellular Data
4. Turn off cellular data for all of your heavily used apps, especially those that receive notifications during background activities
5. One by one, re-enable cellular data for apps as you need it
6. If the issue occurs again, repeat these steps until you identify the app causing the issue and make peace with only using it on WiFi (until a permanent fix is available)

Apple and app developers will need to both work to resolve the root issue that seems to relate to background cellular data usage.

ZuP_ wrote:

I found one of the root causes: If you go to Settings -> Cellular -> Cellular Data and it’s refreshing once a second, this is what’s draining your battery. Some apps seem to trigger it, restarting seems to stop it temporarily until something triggers it again.

Disabling Enable Cellular Usage Statistics at the bottom of that same screen did not fix it.

18.1 did not fix it, either.

I am still in the process of figuring this out myself but I think the issue seems to happen when you have apps sideloaded / installed from 2 different dev profiles / certificates. For example, I have some LOB app from my company, and I sideloaded a custom app I am personally developing, and this causes a huge drain (99% to 9% in 6 hours), phone gets incredibly hot. The moment I uninstall all apps belonging to one of those profiles, I am ok. E.g. uninstall all LOB apps from my company or uninstall the sideloaded custom app I am developing.

Hey, so just a quick update: I think i’ve managed to resolve the issue! Yesterday I checked my photo gallery, scrolled all the way down and noticed “optimizing gallery” at 76%. Force scroll down once or twice just to be sure. Apparently, it was stuck for me. First clue were double albums generated in my photo app (memories, trips, yearly etc.) so i decided to check icloud sync as well and force start the sync, but it did not work at first. I decided to manually delete few blurry images that appeared in my gallery (clearly they were stuck at some point and were easy to distinguish, mostly). I deleted some duplicates from library, deleted all generated albums and memories (original photos remain untouched). Once again kick started library optimization simply by plugging in the charger, leaving wifi on and locking the phone, i kept photo app open just in case. What happened after surprised me, last 24 hours 5% usage from home and lock screen. Hourly usage is not in double digits anymore, i have 2-8% hourly usage, few intervals it shows no usage at all. I think the issue is gone but it might be too soon to tell. In case you haven’t tried this, do it, triple check if there’s anything stuck syncing/optimzing. Fingers crossed this helps you and anyone dealing with this frustrating issue!

Battery drain can be prevented by resetting the settings of the iPhone (Settings - General - Transfer or Reset iPhone - Reset - Reset all settings). It will not delete any data.

It helped in my case - iPhone 14 plus post updating to ios 18 and battery drain is back to normal scenario.

For me the problem is really caused by the calendar app in combination with my Exchange account.

The screenshot shows my iPad Pro (12.9", 6th generation) battery before adding my Exchange account (before 9pm, or 21:00 in 24h-time), then after adding the account and actively using the iPad (from 9pm to 10pm or 21:00-22:00) and finally in standby (after 10pm or 22:00). It drains approximately 50% in 6 hours of standby. Once I turn off my Exchange calendar synch (Mail, Tasks, Contacts do not matter), I again have several days of standby battery life. Removing and re-adding the Exchange calendar or Exchange account as well as restarting do not help. Only if I keep Exchange calendar synch turned off does the problem disappear. But given that this is my work calendar and my work iPad, not synching is not really an option.

I found one of the root causes: If you go to Settings -> Cellular -> Cellular Data and it’s refreshing once a second, this is what’s draining your battery. Some apps seem to trigger it, restarting seems to stop it temporarily until something triggers it again.

Disabling Enable Cellular Usage Statistics at the bottom of that same screen did not fix it.

18.1 did not fix it, either.

10/18/2024 - iPhone 14 Pro ios18/18.1 - So after trying everything possible to fix the crazy battery drain issue...

Using my MacBook Pro (Windows PC will work too), I backed up my iPhone, put my iPhone in recovery mode, did a factory reset and then restored with my latest backup. Absolute game changer....my battery is back to normal and lasting a full day easily. This corrected my issue and hope it does yours

Found fix! Had the same issue. Brand new iPhone 16 Pro with iOS 18. Battery was draining super fast while it was overheating at the same time. Charged all night and the phone had only 70% in the morning because it stopped charging due to overheating. Turned out, my calendar app was using more power than the entire phone and all the other apps combined. After I deleted the calendar app, my phone started working without overheating and lasted for almost 2 days with one full charge.