iPhone 14 rapid battery drain and heating issue after updating to IOS 16.5

What I did is given below

1. Took a backup on iCloud (Which I do regularly)
2. Logged out of the Apple ID
3. Erase --> Erase iPhone - Apple Support (IN)
   1. Keep eSIM Data was the option I chose (See the pic)
   2. .
4. Set up my iPhone and restored it from iCloud Backup
5. 

I continued to have the same issue with the heating.

I repeated the above steps but this time I did not restore from the iCloud Backup. I set it up as a new iPhone.

Waited for 3 days. There is no heating issue, now.

Conclusion.:

• There is no hardware issue!
• This is not an iOS 16.0.3 issue
• Some Apps or iPhone storage and some settings may be heating up the device.

Action Plan:

• I will now slowly get my all data back one by one.
• Using the elimination process I will try to find out which app or settings were causing this...

Now the heating issue isn't there anymore. I am adding apps one by one and keeping tab on the heating issue.

My experience says this is purely caused by some third-party app that you may have installed.

I am not aware of the ambient temperature in which you are using the iPhone. However --> Keeping iPhone, iPad, and iPod touch within acceptable ...

Store the device where the temperature is between -20º and 45º C (-4º to 113º F). Don’t leave the device in your car, because temperatures in parked cars can exceed this range.

Use iOS devices where the ambient temperature is between 0º and 35º C (32º to 95º F). Low- or high-temperature conditions might cause the device to change its behavior to regulate its temperature. Using an iOS device in very cold conditions outside of its operating range might temporarily shorten battery life and could cause the device to turn off. Battery life will return to normal when you bring the device back to higher ambient temperatures. Using an iOS device in very hot conditions can permanently shorten battery life.

The measure of battery health deterioration is subjective and can vary depending on individual usage patterns and not on iOS version updates. There is no universal standard to determine whether the battery health deterioration 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 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.
10. Update iOS: Keep your iPhone's operating system up to date. Apple regularly releases updates that can include optimizations and improvements for battery life.
    1. Update Over-the-Air (OTA) —> Update your iPhone or iPad - Apple Support (IN)
    2. Update using iTunes/Finder —> Update your iPhone, iPad, or iPod touch - Apple Support (IN)
11. Enable Low Power Mode: When your battery is running low, enable Low Power Mode in Settings > Battery. It reduces power consumption by disabling non-essential features.
12. Avoid Battery Drain during Storage: If you need to store your iPhone for an extended period, make sure to charge it to around 50% first. This helps prevent the battery from draining completely, which can be harmful.
13. Disable Dynamic Backgrounds and Motion Effects: Dynamic backgrounds and motion effects use additional processing power and can impact battery life. Use a static wallpaper and disable parallax motion effects in Settings > Accessibility > Motion > Reduce Motion.
14. Limit Widgets: Widgets on the Today View can consume battery life. Remove or limit the number of widgets displayed by swiping right on the home screen, scrolling to the bottom, and tapping Edit.
15. Adjust Auto-Lock Time: Shorten the auto-lock time on your iPhone. Go to Settings > Display & Brightness > Auto-Lock, and select a shorter time interval to turn off the screen more quickly when not in use.
16. Use Wi-Fi Instead of Cellular Data: When possible, connect to Wi-Fi networks instead of relying on cellular data. Using Wi-Fi consumes less power than using cellular data.
17. Enable Airplane Mode in Low or No Coverage Areas: When you're in an area with low or no cellular coverage, enabling Airplane Mode can prevent your iPhone from constantly searching for a signal and draining the battery.

By following these tips, you can help prolong the battery life of your iPhone and maintain its overall performance over time.

Sadly I’ve had the exact same issue since updating, and was hoping it would resolve with 16.5.1…, to no avail. I get the same cut and paste answer, and service centers have told me to change my plug, my battery , or told me I need to reset my phone (loose all my data as I’m not supposed to use a backup or “I’ll just reinstall the same problem..” this is ridiculous as I know Apple has had many complaints on this issue, but no fix!

There are two issues reported by you. Health Drop and Getting heated up.

While heating of the iPhone and battery health deterioration are related, it's important to note that the heating itself is not primarily caused by battery health deterioration. However, it is possible that excessive heating could potentially accelerate the deterioration of battery health over time.

I will address both Battery Health and Heating issue separately in my next two posts.