A great way to preserve battery life on your iPhone is to kill apps that use a lot of energy on your phone. You can find out which apps drain your battery with these steps:
Select 'Settings' icon
Go into the 'General' tab
Select 'Battery Usage'. This will show you which apps have been using the most battery over the past 24 hours or 7 days
Delete the apps that you do not use at all
For battery-intensive apps that you do use: go back into the 'General' tab and then select 'Background App Refresh'
In 'Background App Refresh': slide the apps into the off position if you do not want them to update when you are not using them.
6 iPhone productivity hacks you can use right now: