very worst battery backup of my 5s after the update of 11.1.2

Hi.

Sorry to hear about your battery problem.

There are several things you can do to increase the duration of your battery charge.

First make sure that your charger and/or your battery is not at fault.

If you are certain that they are O.K., then you can take the following measures until a real solution is found. Then you can take back what you have done by undoing the changes:

1) Turn off background app refresh

Settings>General>Background App Refresh ( Turn off those apps that you do not constantly need to be refreshed )

2) Turn off Auto-brightness

Settings>General>Accessibility>Display Accommodations>Auto-brightness

3) Reduce Screen brightness

Settings>Screen and Brightness> Bring the slider to halfway

4) Reduce visual effects

Settings>General>Accessibility>Reduce Motion ( Enable/Turn on the setting )

5) Turn off "Hey Siri"

6) You must also remove or update the apps that are not compatible with iOS 11 in their present state. They may deplete the battery quickly enough if not removed or updated to be compatible with iOS 11.

Hope this helps.

Hi.

Sorry if my post is misunderstood. You don't have to do anything. They are only suggestions and it is up to you to do them or not.

You didn't give the info that you upgraded from 11.1.1. In this case, a simple restart or a force-restart may do the job.

Hope this helps.

Replace the battery with one that is not so old, batteries wear out, that is why they are replaceable.