When I first got my S3 the battery life was great - would easily last over 12 hours. Now rarely gets me through a working day.
Here's what I have tried (none of these worked)
1. Replacing the battery
2. Replacing the handset completely
3. Replacing the SD card
4. Removing the SD card
5. Using a different SIM
6. Keeping the phone in flight mode when not using it
7. Turning off all automatic updates
8. Keeping screen brightness turned down low
9. Uninstalling all my apps
10. Factory resest (many times)
11. Downgrading back to Android 4.1.2 using these instructions - "Google: How to downgrade Galaxy S3 back to Android 4.1.2: tutorial" (I could not do this I just kept getting error messages)
12. Speaking to EE technical help (totally useless)
13. Speaking to Samsung help (completely clueless)
14. All the other tips on the Samsung website - Google "Cell Phones: How do I sustain my Android battery life?"
15. Turning off "Keep WiFi on during sleep"
Not sure what's left. Any ideas? Here's what I have;
Samsung Galaxy S3 LTE (I9305)
Android version 4.3
Baseband version I9305XXUEMK1
Kernel Version 3.0.31-2051278
Build Number JSS15J.19305XXUEML5
SELinux Status Enforcing SEPF_GT-I9305_4.3_0021
My partner has a HTC One which has a great battery life. Don't think I'd buy another Samsung phone after this. Just wiating till my contract ends so I can switch to an HTC.