Most people know the display is one of the most battery-hungry elements of any smartphone, but what they don't know is that the wallpaper they choose – yes, wallpaper – can make a significant difference to battery life. A pure black or generally dark-colored wallpaper or background can actually save power over a lighter one. It just depends on the type of screen you have.

First off, we need to share a bit of display technology information. In the smartphone market, the majority of displays are either AMOLED or LCD. I won't go into too much detail, but if you want to know more (and which one is better for what), you can check out our Smartphone screens explained article. If you just want the black wallpaper, skip ahead to the bottom of the article.

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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 LG G7 THinQ has an LCD display, as does the HTC U11 Plus, Huawei Mate 10, and Sony Xperia XZ2.

Older phones like the U11 Plus and Mate 10 often use LCD displays. / © NextPit

LCDs are also quite power hungry, because every pixel needs to be illuminated whenever the screen is in use.

Display tech explained: AMOLED and OLED

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 S10, Galaxy Note9, Galaxy S9 for example, all use an AMOLED display, as does the Google Pixel 3.

The screen is made up of organic material that actually produces light when a current is passed through it – electroluminescence. AMOLED displays are easier on your battery because every pixel is not always lit up. They also show 'true' blacks because there is no back-lighting.

Battery life: AMOLED vs LCD

AMOLED

You can probably see where this is going: if you have an AMOLED display then you can 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 percent battery life per hour at 20 percent brightness by using a black wallpaper on an AMOLED display, and about 8 percent per hour at full brightness.

These results are based on an always-on screen, but the basic theory holds up even if the figures are not exactly set in stone. Another tester using a different method came up with a general 18 percent saving over the course of a day.

LCD

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 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 their extended battery life (just don't stray too far from a charger while you gloat).

It's not exciting, but it'll save battery power. And it doesn't have to be pure black, just dark. / © NextPit

Other battery life tips for AMOLED screens

There are other things AMOLED owners can do to maximize their battery life, such as 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, you can save even more battery life. After all, we spend more time in apps than on our home screens. You can also set your text and email preferences to have a black background and use 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 Settings and look for Battery, usually in the Device Settings/Device Maintenance section.

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 darker system-wide 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 the savings will still be worthwhile.

Did these black wallpaper tips save you some battery life? Do you have any other tips for conserving battery life? Share them with us in the comments!