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How much energy should a totally black screen be consuming?

I've heard that a black screen will use very little energy, so I tested it myself. I put Aldiko in night mode on a blank page for an hour. My phone used 17% battery (97% from the display) in this hour. Was there some flaw in my testing? Did I misunderstand the claim? Is there some setting that I need to change? Or is this normal?

heliumhelicopter said:
I've heard that a black screen will use very little energy, so I tested it myself. I put Aldiko in night mode on a blank page for an hour. My phone used 17% battery (97% from the display) in this hour. Was there some flaw in my testing? Did I misunderstand the claim? Is there some setting that I need to change? Or is this normal?
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just run your charge to 100%, unplug your phone and put it to sleep immediately, and check after an hour.
theres a true reading.

I think he's trying to get a reading of the battery usage with the screen "running" the color black. By putting it to sleep the screen isnt really running. Try the experiment again see if you get the same results. then try it with a white and lets see the difference.

heliumhelicopter said:
I've heard that a black screen will use very little energy, so I tested it myself. I put Aldiko in night mode on a blank page for an hour. My phone used 17% battery (97% from the display) in this hour. Was there some flaw in my testing? Did I misunderstand the claim? Is there some setting that I need to change? Or is this normal?
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While black uses almost no power, there is a small flaw to your logic. Even though you were displaying an all black screen, anything using CPU cycles in the background is still running (as opposed to if the screen was in sleep mode--which is where the recent bug in facebook came from). The app could also be draining battery waiting for things like touch-sensitive controls.
The claim isn't that black pixels use no power, it's that they use drastically less as opposed to a colored pixel. An AMOLED screen uses a lot of power, and an SAMOLED will at use close to (or more) than that. The idea is that you'll lose far less battery life with a black screen than you will with a screen that's all lit up, which isn't true of a standard LCD.

Kaik541 said:
[...]
An AMOLED screen uses a lot of power, and an SAMOLED will at use close to (or more) than that. The idea is that you'll lose far less battery life with a black screen than you will with a screen that's all lit up, which isn't true of a standard LCD.
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not quite. it depends on what is being displayed.
quoting wikipedia: en.wikipedia.org/wiki/Organic_LED#Disadvantages
Power consumption: While an OLED will consume around 40% of the power of an LCD displaying an image which is primarily black, for the majority of images it will consume 60–80% of the power of an LCD - however it can use over three times as much power to display an image with a white background such as a document or website. This can lead to disappointing real-world battery life in mobile devices.
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as far as super amoled: en.wikipedia.org/wiki/Super_AMOLED
Compared with the first-generation AMOLED, the Super AMOLED advantages are:
* 20% brighter screen
* 80% less sunlight reflection
* 20% reduced power consumption
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vizir said:
not quite. it depends on what is being displayed.
quoting wikipedia: en.wikipedia.org/wiki/Organic_LED#Disadvantages
as far as super amoled: en.wikipedia.org/wiki/Super_AMOLED
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I assume you're more or less commenting on general power consumption, because both of those things backed my side about how it uses even less power when displaying blacks versus whites. The only thing different than what I said is that wikipedia claims it uses less power some of the time, but more power other times, so I'm not sure which part you're disagreeing with by saying "not quite."

[Q] Display, the "color" black and power consumption

IIRC, black uses little to no power on the SAMOLED display.
Knowing that the screen is the largest power hog, I'm curious if anyone could explain why switching to a mostly, or all black wallpaper (on an already black theme/ROM) does not have any appreciable effect on battery life/usage?

Black = Absence of color
In an ideal scenario, the system should not be rendering those pixels and so save power.
I do understand people saying most of the time they use a black wallpaper. But, practically, how many people are on their home screen and for how long? Most of the time we are all using one app or the other. There may be widgets, etc at home screen, but don't think we spend that long staring at it. Personally I don't think I spend even 5-10% of my display time on home screen. So even if I had a black wallpaper, its hardly any battery saver.
1 hour screen on takes ~20% of my battery. So 3 hours of display ~60% of battery. Assuming 10% of this time I am on home screen with black background. That would less than 6% of my battery.
Further take off the power used for displaying home screen elements, widgets, etc, etc at say 50%. This would bring it down further to 3%. Is it worth saving this 3% battery when we could some nice pleasing wallpaper?
Reducing display brightness tends to help though since lowered brightness means lowered power needed to power up the screen.
All this is based on my understanding of the system.
Edit: U cud try applying dark color schemes to apps that support them, like say k9 mail, root explorer etc. This cud help while u r in that app.

I put quote tags around the word color for specific emphasis on black not being a color lol
I use Serendipity 5.12 w/REDROM- almost everything is already black. I decided recently to see if adding a black wallpaper would help the craptastic battery life- since fidgeting w/kernels and modems did nothing noticeable to help (some combos made it worse, yeah).
Again the post is just out of pure curiosity.

diablo009 said:
Black = Absence of color
1 hour screen on takes ~20% of my battery. So 3 hours of display ~60% of battery.
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I noticed the same power consumption also on my Samsung Galaxy S2 (GT-I9100), and I find it really unbearable, since it means that there is absolutely no way I can get more than 4 hours of continuous use without running the battery flat.
Displays, no matter what, should not drain so much power!

Looking so pretty comes at a price, it would seem.

To an artist with a clean canvas, black is a color and white is not. To a photographer, the opposite is true. It all depends on who you ask.

Screen burn :(

I just noticed shadows on my screen a few days ago, it's definitely screen burn as I can see the clock and other icons. Anyone else getting this and would this be a warranty issue?
I never leave the screen on overnight or anything, I usually have the desk clock running overnight but that has it's own built in screen saver so that's not the issue. And the burnt in images are of the desktop icons.
I would have expected far better quality and life expectancy from such an expensive device. My Alienware laptop is now over 2 years old and the screen is perfect even though it stays on longer than the Note.

go-away said:
I just noticed shadows on my screen a few days ago, it's definitely screen burn as I can see the clock and other icons. Anyone else getting this and would this be a warranty issue?
I never leave the screen on overnight or anything, I usually have the desk clock running overnight but that has it's own built in screen saver so that's not the issue. And the burnt in images are of the desktop icons.
I would have expected far better quality and life expectancy from such an expensive device. My Alienware laptop is now over 2 years old and the screen is perfect even though it stays on longer than the Note.
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Screen burn happen on amoled screens not on other type of screens and your alien ware doesn't have an amoled screen...
There's a thread about screen burn go there..

I also have screen burn on the bottom half of my device.
It looks like an eye doctor's test chart. Literally.
How does this happen?

Got it fixed under warranty. I'll never ever be using that "DIMLock" app again as it was the cause of the burnt screen! Well actually now I think about it the biggest culprit was that bloody annoying "Battery fully charged - unplug charger" message which bugs the snot out of me by ALWAYS popping up 5 minutes after I've pressed the power button to put the screen into sleep mode. That dumb message turns the screen on, and because DIMLock was running, the screen would stay on after that, and if I fell asleep in the meantime then it would stay on all night!!
I really wish I could disable that stupid message.

Use a launcher that hides status bar. Use full screen for web browser...etc etc...
Sent from my GT-N7000 using Tapatalk 2

battery life

Just out of curiosity, does anyone know if it uses more battery to have a "white" screen, or a "black" screen? I assumed it was black that was better for battery, but im also using an AMOLED screen which black means pixels are off

ShadyPossum said:
Just out of curiosity, does anyone know if it uses more battery to have a "white" screen, or a "black" screen? I assumed it was black that was better for battery, but im also using an AMOLED screen which black means pixels are off
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I was under the impression that it doesn't really matter on ePaper type screens. The pixels aren't powered in either state, and power is only consumed for switching the state. This is why it's not recommended to use watch faces with seconds counter/hand, as the pixels on the screen would be updating every second, as opposed to once every minute.

Chahk said:
I was under the impression that it doesn't really matter on ePaper type screens. The pixels aren't powered in either state, and power is only consumed for switching the state. This is why it's not recommended to use watch faces with seconds counter/hand, as the pixels on the screen would be updating every second, as opposed to once every minute.
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I thought that the type of display the Pebble uses actually takes a small amount of power to keep on so that animations are smoother.

Chahk said:
I was under the impression that it doesn't really matter on ePaper type screens. The pixels aren't powered in either state, and power is only consumed for switching the state. This is why it's not recommended to use watch faces with seconds counter/hand, as the pixels on the screen would be updating every second, as opposed to once every minute.
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Zekial said:
I thought that the type of display the Pebble uses actually takes a small amount of power to keep on so that animations are smoother.
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The display is LCD. As Sharp describes it, the display uses different amounts of power depending on how fast it needs to change the image. It's an extremely low-powered LCD, and a static image will draw slightly less power than an animated screen. However, the main drain in power is actually the chipset. That's the primary reason why a static image uses less power–it requires fewer resources and thus the chipset will run at a lower voltage.
I actually stopped using my Pebble last year and opted for an analog watch because my battery life was so bad with FWv2.0.2 (1~2 days). I was getting 4-5 days on FWv1.x. I should mention that I used Canvas to display day/date, missed calls, unread SMS, unread email, current temp (1 hr refresh), current climate (1 hr refresh), and my clock had seconds. Each of these was its own element, and I even had separate elements for the calls/SMS/email icons, but the same watch face gave me a work week of battery life on FWv1.x. I would have just downgraded the firmware, but after growing comfortable with wearing a watch all the time I decided to get a timepiece people would look at for the right reasons.
I'm strongly considering Android Wear, but the current offerings are a tad too wide and the displays too low-resolution. I find aliasing extremely off-putting. It's acceptable on the Pebble which has a retro digital feel, but the 360/G Watch R just look like they have cheap LCDs.

Hung0702 said:
The display is LCD. As Sharp describes it, the display uses different amounts of power depending on how fast it needs to change the image. It's an extremely low-powered LCD, and a static image will draw slightly less power than an animated screen. However, the main drain in power is actually the chipset. That's the primary reason why a static image uses less power–it requires fewer resources and thus the chipset will run at a lower voltage.
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Ok, but that still doesn't answer whether or not dark backgrounds draw more power than light ones.

go test it!!... on ur own
put the screen on white for x hr's (x = number of hour's your pebble could completely drain its battery)
then try the black screen:
put the screen on black for y hr's (y = hr's your pebble could completely drain its battery)
if x > y ... white screen consume less power than black screen
u should try it with bluetooth off backlight off .. = more accurate result ^_^

I tried to search a lot for this as well.. all I found was that for traditional e-paper displays it doesn't really matter. But Pebble uses Sharp's some sort of a modified version of e-paper and e-ink tech so not really sure about that. The tech used by Sharp isn't documented much and didn't find any significant info on that. I guess only the R&D department of Sharp can give an actual solid answer to this.

ShadyPossum said:
Just out of curiosity, does anyone know if it uses more battery to have a "white" screen, or a "black" screen? I assumed it was black that was better for battery, but im also using an AMOLED screen which black means pixels are off
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LCD tech uses that same power no matter the color. This display uses power to hold the image, color should not play a factor in battery life. The only real factor in battery life is the number of "refresh" cycles (Not 100% true, but true enough for this purpose).

ShadyPossum said:
Just out of curiosity, does anyone know if it uses more battery to have a "white" screen, or a "black" screen? I assumed it was black that was better for battery, but im also using an AMOLED screen which black means pixels are off
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The main power drains on the Pebble are waking up the processor, changing the display, and Bluetooth communications. There will be power consumed by the display but it's a lot less than the other factors (esp if the display is only changing once a minute or less without any animation). As I recall someone tested with a basic watch face and with Bluetooth off and got well over 30 days before it went flat.
http://www.reddit.com/r/pebble/comments/1zs0jg/inverted_colors_vs_battery/

Always On Display with Edge Only

Hi,
I realized that with the Always on Display and with the setting for Edge only, I still see the stars in the background (using the default wallpaper). Doesn't this mean that even more battery is being used than with the standard full screen Always on Display? Isn't it supposed to only use certain LED's on the screen to conserve battery? If so, is it not possible to have the Edge setting on and save battery by disabling the background?

You could try not using one of the built in live wallpapers, that's where the stars come from.
Hope this helps.

Nixher said:
You could try not using one of the built in live wallpapers, that's where the stars come from.
Hope this helps.
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So does anyone actually use the always on display feature? Seems like it wastes alot of battery

Someone will help you

I don't personally, no point using the battery when your not using the phone, I just see if the led is flashing or not.

unholydoragon said:
So does anyone actually use the always on display feature? Seems like it wastes alot of battery
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About 3% to 5% in my experience.

You can turn on AOD feature, but when you put the phone on the desk for a long time without touching it, just put a small piece of paper (sticky paper) over the top of the screen (above the proximity sensor).
That way the AOD screen will be turned off in a couple of seconds.
When you need to check time or notifications, just lift up the sticky paper and the AOD will come back on.
You can save several % of battery using this way.

vndnguyen said:
You can turn on AOD feature, but when you put the phone on the desk for a long time without touching it, just put a small piece of paper (sticky paper) over the top of the screen (above the proximity sensor).
That way the AOD screen will be turned off in a couple of seconds.
When you need to check time or notifications, just lift up the sticky paper and the AOD will come back on.
You can save several % of battery using this way.
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That, or face down

Weird. Mines on with a custom picture ( I converted to grey scale ) and unplugged overnight i only lose about 3-5% total. I haven't tested without AOD but it can't be using more than 2-3% tops as I'm sure the system is using up most of the battery while I sleep.
Sent from my SM-N950U using Tapatalk

I have a custom AOD and battery life is fine. Its good to glance and see the time without having to pick it up and unlocking.
If your worried turn it off or flip the phone face down. With quick charge on the phone does it really matter?