In the smartphone market, the majority of displays are either AMOLED or LCD, but many people don't know that the wallpaper color you choose - yes, wallpaper - can actually make a difference to your smartphone battery life. Pure black wallpaper, or a dark-colored background in general, can actually save you a significant amount of battery life.
First off, we need a quick bit of display technology information. I won't go into too much detail, but if you want to know more (and which one is better for what) then you can check out our explanation of the major difference between LCD, AMOLED and Retina displays. If you just want the black wallpaper, skip to the bottom of the article.
Display tech explained: LCD
LCD stands for Liquid Crystal Display and it's the same kind of technology you'll find in your televisions, monitors and so on. As the name suggests, Liquid Crystal Displays are actually crystals, and as such, they don't emit light of their own but rather transmit light from a light source behind them.
This means that even if you're looking at black on your smartphone or tablet screen, it is actually black lit up from behind. Therefore, LCDs don't really display "true" black. The Nexus 5 has an LCD, as does the LG G3 and the Xperia Z3.
LCDs are also quite power hungry as every pixel needs to be illuminated all the time.
Display tech explained: AMOLED and OLED
Next, AMOLED. AMOLED stands for Active-Matrix Organic Light-Emitting Diode and it is also used for televisions screens but more notably, for smartphones. OLED displays are similar, but do not use an Active Matrix.
Samsung displays, for example, are usually AMOLED: the Galaxy S5, Galaxy Note 3 and Galaxy Note 4 all use an AMOLED display. The LG G Flex 2 uses a Plastic OLED display and the Google Nexus 6 also uses an AMOLED screen.
As the name implies, the screen is made up of organic material that actually produces light when a current is passed through it – electroluminescence. Because AMOLED displays can be lit up pixel by pixel like on the Moto X, black is "true" black because there is no back-lighting.
This also means AMOLED displays are easier on your battery because every pixel is not always lit up.
Battery life: AMOLED vs LCD
You can probably see where this is going: if you have an AMOLED display then you can actually save some battery life by using black wallpapers, or generally darker wallpapers and themes.
Our friends at XDA Developers did a little experiment and figured out that you can save about 6% battery life/hour at 20% brightness by using a black wallpaper on an AMOLED display, and about 8%/hour at full brightness.
These results are based on an always-on screen, but the basic theory is sound even if the figures are not exactly set in stone. Another tester using a different method came up with a general 18% saving all day.
What about LCD battery saving wallpaper, I hear you ask? Sorry, LCDs rely on back-lighting, so there's nothing you can do to save battery there.
The only thing you can do is set your device settings to Battery Saver mode and try not to turn your screen on all the time. Keep your display brightness as low as possible and your screen timeout nice and short.
The good news is you can have the brightest colored wallpaper and themes imaginable and it won't make a difference to your battery. Just think about that when you look at the gloomy screens of AMOLED owners clinging to extended battery life (just don't stray too far from a charger while you gloat).
Other battery life tips for AMOLED screens
There are other things AMOLED owners can do to maximize their battery life too, like setting as many app themes to be as dark as possible.
If you can change the appearance of a bunch of apps you use frequently (or download a different app that does the same thing but that does allow appearance customization), you can save even more battery life.
After all, we don't spend all day on our home screens but more time in apps. You can also set your text and email preferences to be black background and white text, depending on your device and chosen apps.
The easiest way to figure it out for yourself is to fully charge your device as is and wait until it's almost totally dead and look at how much of your battery was used by the display. Just go into your Settings menu and look under Device Settings for Battery.
Make a note of the percentage your display has used up, then, while recharging your phone, switch to a black wallpaper and repeat the cycle to see the difference.
Give me black wallpaper now
To download a straight black wallpaper for your smartphone background, hit the link here, and don't forget to change your app themes to be as dark as possible to enhance the battery saving effects.
You can also set a system-wide darker theme for your device, change your screen timeout setting to be as short as possible, enable power saving mode, turn off auto-brightness and see how great the battery savings are.
Of course, your battery is used by more than just display, so results will be dependent on your phone usage habits, processor and other variables, but it is still going to save you something worth saving.
Did these black wallpaper tips save you some battery life? Do you have any other tips for conserving battery life?