How to save battery power
1. Off the wifi when not in use
2. Off the bluetooth too.
3. Off Apps notifications for those that you are not using. set them to Manually
4. Bring the brightness down to 50% and set auto brightness : ON.
5 When you have off your Hotspot, Please return to Setting to off your Wifi and Bluetooth after using it. Normally Apple store do not tell their customer on this matter. When you on the hotspot, Wifi and Bluetooth are automatically turn On
6. Finally examine yourself. Fully charge your Iphone before going to bed. Unplug your Iphone at 100% battery and leave overnight till morning and check the following morning how many person left. For me, I managed to save almost 80%. If you find that it has dropped to a very low level then you examine all the apps that you have in it .
7. Always turn off and reboot your Iphone once a week. Iphone is like a computer and doing it will help
8. Last, off the apps by pressing the Home button twice and delete all apps that were running in the back ground.
9. Whatever I have missed, Just Do It , to save the battery.