There's been a lot of talk recently about whether phones with AMOLED screens, like the Samsung Galaxy S, can actually save battery by using darker wallpapers and themes. Reader Steve performed a few tests to find out if this was actually true.
With most modern LCD screens, it doesn't matter what colour your pixels are. If they're on, they're consuming the same amount of power. However, AMOLED and Super AMOLED screens are different. They don't have one big back light; instead, each pixel makes its own light. Thus, a pixel displaying a dark colour actually consumes less power than a pixel displaying a light colour. How much less? Steve explains:
A full brightness white pixel uses 5.8 times more juice than a black pixel. That doesn't mean you could ever increase your battery life by 5.8 times. That's for 2 reasons. The first is that no one spends all day staring at a fully white screen and because no one would every want to switch to a fully black screen! The second is that the screen isn't the only thing using power. . .
Let's look first at changing wallpaper. I've got no idea what the brightness of the average wallpaper is so I'm just going to go with a 50% grey wallpaper for the purposes of this comparison. When the grey wallpaper is used the average pixel brightness is 47%. For the black wallpaper it's 15%. So by changing, I've reduced average pixel brightness by 32%. If I spent all day on the home screen I'd save . . . about 11%.
He goes on to explain other ways in which you can save battery, other than just changing the wallpaper. For example, many apps (like the previously mentioned NewsRob feed reader) offer you the choice of using a standard black-on-white theme, or a white-on-black theme. Steve found that by switching that app's theme, he could save nearly 23% more battery when reading RSS feeds.
I'd highly recommend reading the entire article, as it does a good job of explaining why you save as much power as you do, and it gives quite a few apps that will help you in that endeavor. The bottom line, though, is this: If you have a phone like the Galaxy S, Nexus S or some HTC Desire HDs, for example, you can benefit quite a bit by using darker colours on your phone. Hit the link to read more.