I suggest use 3rd party apps ( all of these need root acces)
I personally use Rootdim it adjust the brightness your phone uses hardware-level controls to actually control your backlight, saving you energy and making for a higher-quality dim screen.
One Power Guard = protect your battery
App cache cleaner
All of them can find at google play store for free...
Alternatively, get the perfect combination of rom and kernel to your device...
I hope i help...