How black wallpaper can save your Android battery

by: Team AADecember 21, 2015
2K

samsung galaxy note 5 vs lg g4 quick look aa (3 of 10)

With every passing year the capability of mobile technology creeps toward its oldest and most powerful sibling, the desktop computer. Also, with every passing year, our mobile devices become more entrenched in our everyday experience, to the point where going without a smartphone for an entire day, or even a few hours, can cause significant distress amongst everyone from casual to power users. Given the importance of smartphones, one would think our most coveted devices would be able to stand the test of time, yet as any modern smartphone user knows, mediocre battery life has us often feeling like a junkie desperately trying to (power)source their next fix. Alas, we have yet to discover the magic bullet that will ultimately put our battery woes to rest. In the meantime all we can do is feverishly optimize our paltry battery life to the best of our ability.

In the past we’ve shared various tips with our readers on how to get the most out of their batteries. This includes taking measures such as turning off unused connectivity options, utilizing power saving modes, and more. When it comes to optimizing your display to use less energy, one common adage is that using a black background can help you use less power. What’s the truth behind this, if any? And does it apply to all display types? Short answer: yes this is sound advice, but no, it doesn’t apply to everyone. The reason why using black backgrounds isn’t a universally good idea is that there are two primary types of display technology found in most smartphones out there: Liquid Crystal Display (LCD), and Active Matrix Organic Light Emitting Diode (AMOLED), and these two standards handle color very differently.

The Note 5 has physical keys, while the LG V10 uses on-screenSee also: AMOLED vs LCD: differences explained190

The more black you display when utilizing an AMOLED panel, the more power savings you get.

While AMOLED is the latest and greatest display technology (aside from plastic OLED) LCD is the most common and well established modern display technology due to cost and age. The more black you display when utilizing an AMOLED panel, the more power savings you get. In general, displays work by emitting varying degrees of light through a pixel. Each pixel is made up of sub pixels that filter light through one of the three primary colours: red, green and blue (some manufacturers have more than three sub pixels). The amount of light that passes through these shaders determines the colour of light emitted from each pixel. Unlike LCD panels, which require a backlight, or light emitting diode (LED), in order to pass light through each pixel, the pixels that make up AMOLED panels are their own source of light. Essentially, when a pixel is displaying black on an AMOLED panel it is entirely off. To emit colour, or white, it must turn on and thus consumer power. This is why AMOLED panels are perfect for features like ambient display, as most of the pixels are not consuming power, unlike LCDs, where the entire LED backlight must turn on no matter how many pixels are actually being utilized.

amoled-power-chart

Ok, to optimize the battery use of an AMOLED panel use black backgrounds and themes wherever possible. Got it. How about LCDs? The answer to this question is also simple, though the rationale is far more complicated. Surprisingly, white (or really any bright color) is actually the most power efficient — though marginally so.

LED-LCDs are made up of five layers: a polarizer, liquid crystal, transistors, another polarizer, and a backlight. LCDs use polarization filters and electrical current to block varying degrees of light passed through the liquid crystal layer by the LED. Light is a wave that oscilates in every direction from the LED backlight. A polarization filter only allows light that oscillates on a particular plane to pass through. A horizontal polarizer allows light that oscilates on a zero degree plane to pass through, a vertical polarizer does the same except on a 90 degree plane. Essentially two perpendicular polarization filters will block all light; if you look through two perpendicular polarized sunglasses all you would see is black.

One of the advantages to an AMOLED display is that you can optimize the colors better to save battery life.

One of the advantages to an AMOLED display is that you can optimize the colors better to save battery life.

The two polarization filters found within an LCD are perpendicular, thus they block all light emitted by the LED. To allow light to pass through the second polarizer a layer of liquid crystal is sandwhiched in between the two filters. The type of liquid crystal used in LCDs is a twisted nematic liquid crystal that has a natural helix structure similar to DNA. As light passes through this crystal it is rotated in ways that allow it to pass through the second polarizer. In order to fine tune the amount of light that passes through shader sub pixels current is applied to the nematic liquid crystal by a thin layer of transistors. As current is applied to the crystal its helix shape untwists, which prevents it from rotating light waves and allowing them to pass through the second polarizer. The more current you apply to a nematic liquid crystal the more it untwists, thus the more light that is blocked.

Long story short, in order to create black, an absence of light, you have to completely untwist the liquid crystal by applying the greatest amount of current, which utilizes the greatest amount of power. Therefore, a brighter color, such as white, is actually more efficient in this case. In practice, the difference in battery consumption for LCD displays is fairly negligible though.

Well, it wasn’t easy, but we have the answer(s). The important takeaways from this analysis are: black uses noticeably less power on AMOLED displays, AMOLED displays use less power than LCDs, and bright colors are the most efficient for an LCD panel. Hopefully this knowledge will help you extract every last bit of life out of your precious phone.

Next – Best Android phones

 

*post written by Lucius Bossio*

  • WAusJackBauer

    Knew this ages ago.

    • neo905

      And yet you refused to share this knowledge…

    • Why you did not share this with me before?

    • Guest

      F**k you, for not sharing this with us.

  • Javid Nazim Mammadov

    Average users don’t know and don’t care about all those stuff. They just buy smartphones to make calls and look fancy.

    • havarka

      and they don’t read webpages about android devices as well :)

    • George

      In that kind of logic an average user wouldn’t also read this page, so I don’t see a reason why your comment exists here as well.

    • Martin Chan

      21st century, no one makes phone calls anymore.

    • Avieshek Rajkhowa

      There was a time nokia was used for vibrators

  • Tony G.

    I’m still wondering why Google removed the choice to switch to the dark format.

    • On Galaxy S6 there is a theme called Material Dark, it improves my battery life and looks similar to stock Android.

      • Tony G.

        I didn’t know the Samsung’s have that…….that’s smart.

    • Byfield97

      I hear rumors that it could be rolled out in a future updates. But I’m taking it with a grain of salt.

      • Tony G.

        I heard that too. They should just give the choice.

        • Byfield97

          It would be nice, but all we can do right now is wait and see.

      • Avieshek Rajkhowa

        Android 6.1 in March?

  • Marty

    Black wallpaper on an OLED display will save battery life. But not on LCD. It won’t make any difference on an LCD because the backlight is on all the time when the device is being used.

    • Andrei

      It makes a difference on LCD too. You save battery by going with light coloured wallpaper (not brightness) because on LCD you have tiny windows that you need to dim in order to show dark colours. This dimming is using battery. Search for electro cromic film on youtube and imagine that film on millions of tiny dots on your screen controlled individually.

      • Marty

        But the guy was talking about black saving battery life. Black will only save BL on OLED displays because the black isn’t being powered. Whereas the black of an LCD still has a backlight powered on. The only thing making an LCD black is, as you say, the LCD pixels darkening.

        I think the ideal display would be an LCD that uses white OLEDs as a backlight. Do away with the ordinary LCD backlight and adopt OLEDs to light an LCD. That way only the lighter and colored portion of the display would have backlight power.

        • Andrei

          Yes. You are correct. I re-read your comment.

  • Android 5.0 changed to white background

  • MauriceGriffin

    Of course we commenters all know this. My question is what’s the best dark layers theme for Marshmallow that won’t randomly make system stuff unreadable :-)

  • Prominence

    You could have just cut to the point being the conclusion to LCD and amoled displays Instead of explaining the working of LCD and amoled . Those stuffs are engineering topics and seriously you’ve explained that better than any text book .

  • Google Launcher basically voids any battery savings with all of its white backgrounds.

  • Roee

    So pure black is noticably better on AMOLED, but dark yet not completely black still requires the pixels to turn on, does it really use less energy?

    • mobilemann

      No, and yes. (LCDs have not stood still)

  • D13H4RD2L1V3

    I found AMOLED displays to not be all that power-consuming when the entire display is lit. Maybe a little more than LCD, but I can’t notice any difference. Maybe it’s because I’m not actually testing them.

  • shoulda change article title to “How black wallpaper can save your AMOLED Smartphone battery” or something

  • Avieshek Rajkhowa

    Quantum-dots Display?

  • Avieshek Rajkhowa

    The real advantage of AMOLED is that the colours are still maintained at low bright levels as opposed to LCD (And people mostly surf at night, if not facebook)

    As for the argument against ‘burn-in’, particularly the blue levels in AMOLED, when people are making a cry of sleeping-cycles being interrupted by the blue lights emitted off the displays and tweaks like ‘Twilight’ & ‘flush’ are a phenomenon now, shouldn’t it rather be, an advantageous thing? Its healthy than
    -think different :D

    • mobilemann

      it’s not burn in. that’s plasmas. It’s the blue sub pixels die at twice the rate of the others in AMOLED, which is why about 70% of gnex’s look like utter trash now.

      Don’t share information you don’t have.

      • Avieshek Rajkhowa

        Woo… Mobileman being sad santa

        • mobilemann

          L E A R N

          • Avieshek Rajkhowa

            lol

          • mobilemann

            i also find your lack of knowledge humors. However, it’s not an asset to you. You’re stupid.

          • Avieshek Rajkhowa

            Its fruitless to argue with an arrogant person even in this spirit of Christmas holidays. I could ‘ve explained elaborately to change the perception of how you take the expression of the original comment but thats only viable to a man of curiosity and not narrow mindedness. Its not viable for any wise person to disrespect one, therefore instead of spending the precious moment of mine to an argumentive reply to sum1 let’s just hope you ‘ve more experiences in life. You may reply to suit u’r narrow mindedness and egoistic self-image and worthless value to own life.

          • mobilemann

            am i wrong? I didn’t know we were talking about the christmas spirit, as i normally only comment on tech. If anyone’s view needs widening, in especially in terms of technology, it’s you.

            None of this isn’t true, and if you actually want to talk arrogance kid, arrogance is trying to play off you knew what you were talking about and informing others, what you did. I informed people, you did the opposite. Pretending to know stuff, to support a brand, so i guess you’re just a cheerleader.

            Way to take this one home to the end. Keep it going if you want it to get even worse for you.

  • AHM3D

    if only there was a link to dl

  • Jim Scott

    Thats a revealing story. I am uploading black wallpaper on home and lock screen on my Samsung S6 Edge

  • kturner

    I love how people make sweeping generalizations about smartphone usage based on their own (limited) usage. Things like “no one uses smartphones to make calls” and “only used at night for facebook”, “everyone knows”, “average user”. No empirical data to support these comments, just pulled out of an imaginary hat or somewhere less civilized. Sharing of information, tips and tricks to get the most out of your devices is great. For those of you not offering anything useful, just shut up and keep trolling. Yes, i will now practice what I am preaching. Adios!