Best battery saving application for Nexus 5 ?

Hi friends
I have a NEXUS 5,I buy this phone before one week but the battery of this phone going down very quickly, So i am thinking about any App which is used to save my battery but not sure which one is good? can any one tell me the good app for this phone?
is it Qualcomm's very own battery guru or battery doctor? Or any other good app for saving battery?

I suggest you one app DU Battery saver it is helpful to save your handset battery life. your handset battery last longer, and can help you get up to 50% more battery life for your Android phone. You can solve battery problems and extend your battery life.