[Android General] BatteryMentor:
Screens are the largest consumers of power in mobile devices, but exactly how much power does a screen use? And more importantly, how do different types of screens compare to each other in terms of power consumption? To answer these questions, we used a new tool called Battery Mentor to evaluate the screens of several different devices.

We used Battery Mentor’s Screen Test* feature to collect the following metrics**:

SCREEN POWER: The amount of power the screen is currently using (lower is better).

POWER / BRIGHTNESS: The amount of power the screen uses for each percent of brightness. Since this metric is independent of the screen's brightness level, it is useful for comparing screen power across different devices (lower is better).

MAX POWER / PIXEL: The amount of power one pixel uses when the screen is at maximum brightness. This is a good indicator of how power-efficient the screen is (lower is better).

* The option to run the screen test is not supported on devices that use estimated power.

** These metrics are available in Battery Mentor 1.0.1 and above.

For more details about Battery Mentor, please see here:

http://xdaforums.com/android/apps-games/app-battery-mentor-t3498470

Test Procedure:

Close all apps running in the background

Launch Battery Mentor

Wait for 30 seconds or until the real-time power stabilizes

Open the Navigation Drawer and press Settings

Press Run Screen Test (or Rerun Screen Test if it was run previously)

Select 10 minutes

Wait for 10 minutes until the screen test completes

Press Screen Details

Make a note of the POWER / BRIGHTNESS value and the MAX POWER / PIXEL value

Repeat steps 1-7 to verify the results (for our test, we repeated the test 5 times, dropped significant outliers, and calculated the average of the POWER / BRIGHTNESS and MAX POWER / PIXEL values across all tests)

Devices:

Here are the devices that we tested (specs obtained from www.gsmarena.com):

Nexus 6 (2014)(Android 7.0)

Display Type: AMOLED (AMOLED capacitive touchscreen, 16M colors)

Display Size: 5.96 inches

Resolution: 1440 x 2560

Nexus 5 (2013)(Android 6.0.1)

Display Type: IPS (True HD IPS+ Capacitive Touchscreen, 16M colors)

Display Size: 4.95 inches

Resolution: 1080 x 1920 pixels

Nexus 7 (2013)(Android 4.4.2)

Display Type: IPS (LED-backlit IPS Led capacitive touchscreen, 16M Colors

Display Size: 7.0 inches

Resolution: 1200 x 1920

Results (lower is better):

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Conclusions:

AMOLED screens consume much less power than IPS screens. In our test, the AMOLED screen consumed less power (per brightness percent) than the IPS screen (Nexus 5) despite being 45% bigger in terms of screen area and having 78% more pixels. In terms of power-efficiency, the Nexus 6 (AMOLED) screen used nearly half the power per pixel as the Nexus 5 (IPS) screen.

Larger screens use more power than smaller screens (independent of screen resolution). In our test, the Nexus 7 (IPS) screen consumed 40% more power per pixel than the Nexus 5 (IPS) screen.

We’ll need to collect additional data from other devices to see how power consumption scales with screen resolution. Although we expect the power consumption to increase as screen resolution increases, we're not sure by how much. If you get a chance to run the Screen Test on your device, please take a moment to post your results and device information in the comments below.

How much power does your screen consume? Let us know in the comments!