Upgrading to ios 12.4 And the battery ends quickly

Hello,

1) Have you tried a restart?  If not, do it now.

2) See the section "View battery usage information" in the link below to see the apps that are consuming your battery:

Maximizing Battery Life and Lifespan

3) Check “Battery Health” in the link: 

iPhone Battery and Performance

4) If all else fails, consider a battery replacement:

iPhone Battery & Power Repair

Good luck.

Several people have found that performance settles after 48 hours of spotlight reindexing etc.

There is also anecdotal evidence of one or more social media apps with runaway background activity and total overnight battery drain. If still suffering high drain try a backup then restoring to factory settings.

If that fixes it add back essential apps one buy one. Report back if successful.

There is no way of going back.

Did you try any remedy ?

There's no such thing as iOS 12.4. At least not yet... The current version is iOS 12.1.4

I will say it once more.

Backup in iTunes

Ensure you photos are somewhete safe

Restore the phone *as new*

If it still drains it is a hardware fault.