Hey, I’ve had my S9+ for a less than a year. In the past week my battery has died very quickly.
From 100% to 13% in less than ten hours while the phone is barely in use and locked.
What could be the problem and how can it be fixed?
Have you downloaded any new apps recently or maybe you have some pending updates for the ones you have downloaded.
You can try some self help troubleshooting tips such as....
Check your Battery Stats to see if something stands out.
Can you screenshot yours and post it in your reply please.
You could try a soft reboot by turning the phone Off and On to reset it.
More detailed reboots are to...
Clear the phones system files cache.
No info is lost this way.
Tondo this Turn the phone off and then from a set series of button presses go into the phones system files cache and clear it.
A more broad sworded option is to back up then remove any relevant Sd card and Factory Reset as a very last resort.
That and or a Samsung Experience Store or Samsung Service Centre can run a diagnostic test on the phone.
Current Phone ~
Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+
Samsung One Ui 3.1/ Android 11.