This tweak automatically
switches to the Low Power Mode when your device is locked. On this count
you will have less charge left and your device will charge faster. You can
also set a battery level to turn on the Low Power Mode automatically.
Low power will also stay on while charging when the device is locked to facilitate faster charging.
Confirmed working on iOS 10, I have tested this on my iPhone X on 11.1.2 and need results from other devices and iOS versions. It should work for 9.3+ but I do not have anything to test on.
This is an alpha build and should be stable you can get it FREE on my repo at https://smokin1337.github.io