Rapid battery drain after iOS 18.6 update on iPhone 12 Pro Max

Installing iOS 18.6.1 also solved the battery drain issue on my iPhone 13.

I installed 18.6 last night before bed, charged overnight, and woke up with 100% charge. Using the phone (web surfing and Wordle with Safari, no other apps open) for 90 minutes this morning it went from 100 to 57% charge and felt very warm. Checked for update and installed 18.6.1. The phone has used 2% battery in the last 2 hours since updating and feels normal (room) temperature.

The measure of battery health deterioration/drainage is subjective and can vary depending on individual usage patterns. There is no universal standard to determine whether the battery health deterioration/drainage is normal or abnormal because it heavily relies on how the battery is used and maintained.

Protect & Prolong the Life of your iPhone's Battery:

1. About the battery usage on your iPhone, iPad, and iPod touch ...
2. Batteries - Maximising Performance - Apple (IN)
3. iPhone Battery and Performance

Try to monitor Battery usage by iPhone Activity as shown below

What is shown under battery usage? Checking that would give you an indication of the usage behavior.

1. Background Activity
2. Notifications
3. Connected to Charger
4. Or any Other

See the pic below (iPhone 12 Pro iOS 17.3.1)

"Show Activity" feature will show you more info see the pic below

Try some of these options too.

To prolong the life of your iPhone battery, you can follow these tips and best practices:

To prolong the life of your iPhone battery, you can follow these tips and best practices:

1. Optimize Battery Charging: Enable the "Optimized Battery Charging" feature on your iPhone. It helps reduce the wear on the battery by slowing down the battery aging process. You can find this option in Settings > Battery > Battery Health. About Optimized Battery Charging on your iPhone - Apple Support (IN)
2. Avoid Extreme Temperatures: Extreme temperatures, both hot and cold, can negatively impact your battery life. Avoid exposing your iPhone to excessive heat or cold, such as leaving it in direct sunlight or in a freezing car.If your iPhone or iPad gets too hot or too cold – Apple Support (UK)
3. Use Original Chargers and Cables: Always use Apple's original chargers and cables or certified third-party accessories. Low-quality chargers or cables can damage the battery and reduce its lifespan. Identify counterfeit or uncertified Lightning connector accessories - Apple Support (IN)
4. Avoid Draining the Battery to Zero: Charge it whenever the charge becomes lower than 20%. The rest is up to you when to charge. how long to charge, how often to charge, which adapter to use starting from 5W to 140W USB-C Power Adapter etc.
5. Optimize Display Settings: Adjust your display settings to optimize battery life. Lower the screen brightness, enable auto-brightness, and use shorter screen timeout durations. Adjust the display and text size on iPhone - Apple Support (IN)
6. Minimize Background App Refresh: Limit the number of apps allowed to refresh in the background. Go to Settings > General > Background App Refresh and disable it for apps that don't require real-time updates. Switch apps on your iPhone, iPad, or iPod touch - Apple Support (IN)
7. Disable Push Email: Push email notifications can drain your battery quickly. Instead, set your email accounts to fetch data manually or at longer intervals. You can change this setting in Settings > Mail > Accounts > Fetch New Data.
8. Disable Unnecessary Notifications: Reduce the number of unnecessary notifications you receive. Go to Settings > Notifications and customize which apps can send you notifications.
9. Limit Location Services: Some apps use GPS and location services in the background, which can drain your battery. Go to Settings > Privacy > Location Services and disable location access for apps that don't require it.

Updating to iOS 18.6.1 fixed it for me.

It's not always the iOS update's fault!  Many things can cause phone problems.  If you tell people you think it's an iOS update, it might make it harder to fix or find a solution for the real issue.

Remember, the right question often leads to the solution!

Was/Is your device Jailbroken? If that's the situation, please be informed that attributing the issues to iOS updates may not be accurate.

iOS updates aim to enhance user experience, boost security, and fix bugs rather than disrupt core features. The majority of the issues after updates might stem from underlying, unmentioned factors. Updates won't typically alter personal data but may refine settings or features. Backup before major updates for safety. Review Apple's update details and backup advice for a smooth process.

Kindly consider checking your settings and addressing any device issues before attributing the issue to external factors. This could be a pure coincidence that the iOS update affected the iPhone functions.

Before initiating a standard iOS update, it's advisable to create a backup. Have you completed this step? If yes, proceed with the restoration from the backup.

See what each update does: About iOS 18 Updates, About iOS 17 Updates, About iOS 16 Updates, About iOS 15 Updates, About iOS 14 Updates, About iOS 13 Updates, About iOS 12 Updates, and so on...

It surely is not iOS 18.6 because...

I conducted a thorough search of this forum using the term 'battery drain after iOS update' and uncovered numerous posts detailing similar issues across various iOS updates. This suggests that iOS updates may not consistently be the root cause. Below are a handful of examples extracted from the search results:

• iPhone 14 Pro Max battery drain after iOS 17.0.1 update
• iPhone 6s battery drain after iOS update 15.7.1
• Re: Battery draining quickly on my iPhone 13 after iOS 18.5 update
• Battery Drain rate after iOS 16 update
• My iPhone 13 battery is draining fast after iOS 18.3.2 update
• Battery Draining after the ios 16.5 update
• Battery Draining after updating iOS 18.1.1
• Re: Battery drain after ios 15.6 update
• battery drain after ios 10 update
• Re: iPhone battery drain after updating to iOS 16.3

I'm sorry but I find your response a little disingenuous. The OP has updated his phone and is experiencing instant battery drain which is an issue that users have been having across the board with all of the IOS 18 updates myself including. I've tried everything, including all of the minor details and fixes that are only really obvious if you're an actual computer programmer! I had remote access analysis from Apple that said my battery was in great shape. The Apple support staff that I spoke to said that I had to back up my iphone, factory reset it and restore it from my mac. Which I did despite it taking several hours (including the time it took me to re-install all of my music) only to find that it didn't resolve the issue and that the battery drain remains terrible. The phone is just over a year old and cost me £899.00 which is an extortionate amount of money for what is given the current battery life, a substandard product.

TannerVegas wrote:

The phone is just over a year old and cost me £899.00, which is an extortionate amount of money for what is given the current battery life, a substandard product.

Purchase Apple Products from the Apple Online Store, Apple Retail Stores, and many Apple-authorized resellers and wireless service providers.

I have the same issue as well on my 13 mini and my watch series 7 (watchOS 11.6) It’s draining rapidly overnight too even when both of them are in airplane mode.