iOS 13.4.1 battery drain and heating - iPhone 7 plus

Hi There,

I have been experiencing drastic battery drain and heating after the 13.4.1 update and was hoping to get it resolved in next update ie. 13.5. But to my disappointment, nothing changed with the battery nor heating. My device was running normal and used to get a good backup and suddenly an update spoiled, resulting in drastic battery drain of about 1-2% per minute of use and around 10-13% drain in idle for a period of 8 hours.

Battery health: 87% and supports peak performance and optimized charging.

Below steps might help someone, on probable settings you can check in your device who has battery drain issues: irrespective of your iOS version or device model.

The battery app did not show any apps that use battery excessively. So just helpless. I started to troubleshoot myself.

Here is what I tried:

1. Mail - Fetch (manually) - (happened during an earlier update)- Saved some battery drain but not solved.
2. iCloud backup - Turn OFF : thinking it might be stuck in between upload and causing battery drain (happened during an earlier update). - No change
3. Disabled background app refresh - No change
4. Turned off location services - No change
5. Vibration - OFF - No change
6. Update all apps - No change
7. Reset - "Reset All Settings" - No change
8. Removed apps one by one - No change (At this point i was already frustrated and took number of days to troubleshoot and observe changes. It made me think either my device has become faulty and even thought of getting a repair or new device).
9. Installed CPU-x to monitor CPU usage, RAM & Network. Found CPU usage was high causing heating during browsing and charging. High CPU usage in idle along with other apps usage and charging etc was causing heating issues (may be a bug leftover from iOS update).
10. Bluetooth and WiFi - Turn OFF from settings when not used (not from control center). - Saves battery, but issue not solved.

Why buy an expensive device with all features and turn its best features off to use the device, worthless!! I was not ready to give up.

1. Did a factory reset, erased all content and used the device for a day (in stock condition) without restoring backup. - Battery is back to normal. All good.
2. CPU-x shows stable cpu usage, idling when not used and no network usage. Heating issue disappeared.
3. I was happy and did a restore from iCloud (i noticed users complaining about restore from PC did not help, so did not bother to try it). Allowed time to finish all downloads and become stable after the restore.

Result:- Battery drain during idle disappeared. From 10-13 % overnight came back to normal 2-3% drain, but during screen on time, the battery continued to drain 1-2% per min. I had reset all the settings & removed apps one by one earlier which did not help. So what is left!!

The battery app now started showing usage hours in "Home and Lock Screen" category which never came to top of the list (as far as I could remember). I had no steps left to try. Being a home screen thing, i just tried and turned off dark mode. Voila. Sudden change in battery drain. The battery drain has now become normal (1-2% for 10-12 mins of screen on time/app usage).

So for all who have battery drain issues out of nowhere after the update, please try above troubleshooting steps which I have come across in various versions of iOS updates. Would be glad at-least one person get benefited. Fingers crossed till next update. Probably I wont update iOS from now on. Currently running on 13.5.

Apple, you need to check the dark mode bug. I can show you how much battery drains if i just turn on dark mode and things back normal if i switch it off ( no other changes). I am not a techie or apple engineer. Above facts are based on my observation during my journey from iOS 9 - iOS 13.5.

Thanks,

Krish