Just like major initiatives before it like Project Butter, Android L brings a new project called "Project Volta" to improve battery life in the latest version of Android. Project Volta is an umbrella name for several improvements in Android L, including optimizations of subsystems, better display of battery usage, a new job scheduler and of course a new Power Saver mode.
A new app called "Battery Historian" will give users a better idea of what's using battery on their phone, giving a true representation of what was draining battery throughout the day so they can take action. On the developer side, a new Job Scheduler API can keep the device asleep a higher percentage of the time, then schedule tasks to run at more opportune times such as when it is charging.
Battery Saver mode in Android L, similarly to what Samsung and HTC are doing in their latest software suites, shuts down unnecessary processes, slows refresh rates, slows down the CPU and even cuts down on background data to extend battery. Google says that Battery Saver can extend battery by up to 90 percent if it is used for a full day on a Nexus 5.