iOS 11 is has a issue of draining battery in iPhone. Here I am suggesting 3 ways or tricks to improve your battery life of iPhone specially with iOS 11. 1st turn off your Wifi and Bluetooth directly from setting not from toggle bars buttons because the toggle buttons turn off only it in semi state not completely therefore its catch unnecessarily wifi or bluetooth signal and drains battery. 2nd Is the Background refreshment, this process is synchronising process of all apps which refresh apps data from servers and internal with specific app, you here can turn off the sync process of the unnecessary apps and can save your battery life. And improve battery life of your iphone. 3rd one is Battery saver mode which is design from apple but in this case you may affect with performance of your phone, I am personally use it very less. Thank you guys I hope your will find improve battery life of your iphone.