Friday, September 26, 2014

Samsung Galaxy S5 - Grayscale Test Battery Saving

Yay, the Samsung Galaxy S4 and S5 have a power saving mode that removes all colors and turns the screen Gray. The idea seems to be that this will save power on the AMOLED screen due the way it operates.

On an AMOLED screen, a pixel (dot) that is black uses no energy because every pixel emits its own light. On a regular LCD or IPS screen, a backlight is always running, and turning pixels black or white has almost no effect on battery use.

In my opinion, the Samsung Grayscale looks hideous, but if I can get some good power savings out of it, then it may be worth it.

I ran 2 tests. Criteria for both:
  • Screen on 100% brightness for 90 minutes continuous
  • View on home screen
  • No obvious apps running
  • Airplane mode with all networks off
  • Begin timing just as percentage decrements

The first test was of Color. The second test was of Grayscale. Before entering Grayscale powersave mode, I turned off all other power saving features (cpu, framerate, touch key, etc).

Here are the test results:

  1. Battery: 90% - 81% 90minutes color 9% decrease
  2. Battery: 79% - 71% 90minutes gray  8% decrease

After running both tests:
Color used 1% more battery than Grayscale.

It is my opinion possible that this 1% difference could be due to anomaly or other factors. I did not repeat the test again.

This battery savings does not seem very worthwhile for the average user. For the extremist battery saver that doesn't mind the look of everything Grayscale, then it might result in a small savings.

I would speculate that instead of using Grayscale, it may possible to get even greater powersavings by simply using a black background the homescreen.

Thanks for reading. Please post a comment below if you know of any other battery saving tests for Samsung AMOLED screens.