Do black interfaces really save power on AMOLED displays?

AMOLED vs LCD display technology is a long running dispute. One of the most commonly touted benefits of AMOLED is additional power saving when the display contains mostly black or darkened pixels. This is particularly important as displays are the biggest battery drainers, but is it really true?

The theory behind this claim is quite simple. LEDs require less current when less brightly lit, and black pixels are just LEDs that are turned off, therefore requiring no power at all. LCD displays, on the other hand, use a backlight that is on even when displaying black pixels. Instead the light filter blocks light coming from the backlight, but power is still being consumed. Ergo, AMOLED is more energy efficient that LCD when displaying blacks.

To put this theory to the test, Greenbot grabbed the latest Moto X, which features a 1080p AMOLED display, and an app to measure current drawn from the battery. The amount of current draw was then measure at repeated intervals using two different display modes on the Reddit Sync app, which switches between colored and mostly black backgrounds.

Of course, this type of test can’t take into account power draw from other components. However, the test aimed to limit the impact of other processes by killing background tasks, sticking the Moto X into aeroplane mode, and setting the display at a constant 50 percent brightness. Time for the results.

The theory holds true. Using the AMOLED setting in the Reddit Sync app indeed helped to cut current draw, prolonging the device’s battery life. Power consumption was down 41 percent overall compared with the full colour version, which is a pretty decent energy saving.

Of course, individual scenarios will vary and there aren’t that many apps which offer black background options to help AMOLED devices save on battery life. The other half of the argument is that LCD has a lower current draw at high brightness settings than AMOLED, meaning that AMOLED isn’t necessarily a efficient as LCD to begin with.

AMOLED handset owners might be able to squeeze an extra hour or two out of their handsets, so long as they can find black background versions of their most popular apps. Debate settled?