Running out of battery is extremely frustrating, so I consider extended and consistent battery life essential features for the devices I use.
The release of Android 6.0 include Doze, which I’ve found to be an extremely effective battery saver because unlike other battery savers like “Battery Saving Mode,” I never notice when my Device is dozing. Doze is described on the Android site:
Doze extends battery life by deferring application background CPU and network activity when a device is unused for long periods.
Idle devices in Doze periodically enter a maintenance window, during which apps can complete pending activities (syncs, jobs, etc.). Doze then resumes sleep for a longer period of time, followed by another maintenance window. The platform continues the Doze sleep/maintenance sequence, increasing the length of idle each time, until a maximum of a few hours of sleep time is reached. At all times, a device in Doze remains aware of motion and immediately leaves Doze if motion is detected.
I have found that since updating to Marshmallow, my Droid Turbo 2 and TouchPad both have significantly better battery life.
Battery Saving Mode
Battery Saving mode is also an extremely effective battery saver, but comes at the expense of considerable limitations to functionality.