Max Screen Brightness Battery Run Down: Test Results!

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gogol

gogol

Senior Member
May 20, 2005
3,735
216
You should consider setting the min brightness to a value that is still applicable for viewing. For example brightness at 5% or 10%, and not at the lowest setting. Because people hardly use that lowest brightness setting. I dont know if this is possible with default setting in ICS, but I use Widgetsoid to set brightness at certain level. With my current Nexus S, I set to 8% and I can still see comfortably :)

And do not use an app like JustPicture, but use the default launcher background. Remove everything from the screen to make as minimal asossible with everything default. This is to remove the app influence. Then set the screen to not timed out.

I did this similar test in the past with Amoled screen of htc Desire :)

http://xdaforums.com/showthread.php?t=660853

Davidsmonkeyroost said:
Not too scientifically - I made it black in MS Paint. It's a JPG. I tried it out in portrait and landscape on full brightness and I can't see the edges of anything on the screen, so it's as black as the rest of the black in Gallery. If you have a better way, then I'd gladly take a 16x10 black image if you think it is more black.

Min brightness will be using the brightness slider in settings. I haven't rooted the phone so don't see any way to get it lower. I tried the app "Dimmer" but it's the same brightness as far as I can tell as min setting. Also I figured the min setting was relevant to more users than something they can't easily get to (or probably see on screen!).

Do you have any suggestions? I want to root, but my home PC can't see my GNex. It's being a pig about it and I haven't got Broadband ATM... Hope to root as soon as I can.
Click to expand...
Click to collapse


---------- Post added at 04:01 AM ---------- Previous post was at 03:46 AM ----------

I like this idea of standardized XDA battery test. Just an app that do this:

Save settings
Set screen time out to no
Set to airplane mode
Turn off anything else like bluetooth, gps, etc.
Choose test mode
... Pure white test at max brightness
... Pure white test at lowest brightness
... Pure black test at max brightness
... Pure black test at lowest brightness
... Simulated web page at max brightness
... Simulated web page at lowest brightness
Do the test
... Record battery drain every 30 minutes
Restore settings

Thats for a start :)

The simulated web page is just an image with text and some images or even animation.

Any developer interested? :)

Nebucatnetzer said:
This sounds more than difficult. Not a clue how one could do this.

As soon as I have my device I'll probably start a thread where we can think about a standardized (what a stupid word) battery test.

Curios how your second test goes.
Click to expand...
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D

Davidsmonkeyroost

Senior Member
Jun 30, 2007
53
76
Hertford
gogol said:
do not use an app like JustPicture, but use the default launcher background. Remove everything from the screen to make as minimal asossible with everything default. This is to remove the app influence. Then set the screen to not timed out.
Click to expand...
Click to collapse

Good idea. I do have my concerns over Just Pictures elevating the Android System part of the test, but it should be consistent. I was worried that JP might have a very very dark background image which would show at the sides of my black image, however the photo I took last night shows that the entire screen even the gaps between the android buttons is the same uniform dark grey.
 
M

matt2053

Senior Member
Dec 17, 2010
2,066
295
42
Clearwater, FL
Guys, stop suggesting he use normal brightness settings or browse the web etc. That would introduce variables that would ruin the results. He's not testing to see how long the battery lasts. He's testing to see if white vs black display images affect battery life.

Sent from my Galaxy Nexus using XDA App
 
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Nebucatnetzer

Nebucatnetzer

Senior Member
Feb 4, 2011
5,820
6,598
matt2053 said:
Guys, stop suggesting he use normal brightness settings or browse the web etc. That would introduce variables that would ruin the results. He's not testing to see how long the battery lasts. He's testing to see if white vs black display images affect battery life.

Sent from my Galaxy Nexus using XDA App
Click to expand...
Click to collapse

Read the whole thread and you'll understand.

Sent from my HTC Desire using XDA App
 
Dmw017

Dmw017

Senior Member
Aug 6, 2011
696
87
Cmon ppl hit the Thanks button at the bottom of the OP's post ;p he deserves it!
 
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Davidsmonkeyroost

Senior Member
Jun 30, 2007
53
76
Hertford
sblantipodi said:
great thread.

---------- Post added at 03:01 AM ---------- Previous post was at 02:56 AM ----------

what is this:
http://attachments.xda-developers.com/attachment.php?attachmentid=798746&d=1322561821

why your screen is so "dirty" have you got a defective screen?
Click to expand...
Click to collapse

Its crap in my camera body. When i point it downwards and do a long exposure, i sometimes get dust in the photo.

The phone screen is perfect, not a dead or misfiring pixel to be seen.

What you can see is the greenish glow on the screen. This is as black as the screen goes. It isnt switching the black pixels off.

Please bear in mind that this was a 1 second exposure, ISO 1600, F1.4 in a darkened room, but still, on is on.
 
D

Davidsmonkeyroost

Senior Member
Jun 30, 2007
53
76
Hertford
Right, first off an apology : the last week was a bit bit if a mess for me and as you can see, i havent finished all the testing. Sorry chaps.

Will be finishing it next week. Check back in a few days.
 
W

wonshikee

Senior Member
Nov 11, 2011
340
47
Something interesting I noticed is that if you use a #000 image or a webpage, it's not true black - just a very dark pixel.

But if you open up youtube, let the video finish and don't touch it, then view it in landscape mode - the black pixels appear to be turned off completely, because you can see some stuff behind it. You have to be in a very dark room to do this.
 
D

Davidsmonkeyroost

Senior Member
Jun 30, 2007
53
76
Hertford
just4747 said:
Hey OP, how come in the pic of the white screen (http://attachments.xda-developers.com/attachment.php?attachmentid=798046&d=1322509388), it looks very much like a pentile screen look which this phone is supposed to not show. It has those fairly large ugly grid lines showing. Make sure you enlarge the browser pic to 100% to see it.

Is this actually visible on the screen in person???
Click to expand...
Click to collapse

Hi Just4747. I wouldn't worry too much about any shapes or lines you see in this picture - you can't see it in real life. It'll be from the vertical lines on my cameras CCD sensor not being quite parallel with the vertical lines on my Phone, creating diagonal lines in the picture, kind of like when you see someone with a stripy shirt on TV. Makes your eyes hurt...
 
Last edited:
D

Davidsmonkeyroost

Senior Member
Jun 30, 2007
53
76
Hertford
wonshikee said:
Something interesting I noticed is that if you use a #000 image or a webpage, it's not true black - just a very dark pixel.

But if you open up youtube, let the video finish and don't touch it, then view it in landscape mode - the black pixels appear to be turned off completely, because you can see some stuff behind it. You have to be in a very dark room to do this.
Click to expand...
Click to collapse

Hey wonshikee, your first point is shown in my long exposure photo in the OP, it looks green in the photo, but it's really a dark dark grey.

The Youtube experiment you mention sounds interesting. I'll have to try this tonight with my SLR to see if it's captured as proper black. What happens if it displays the navigation buttons? Does the screen become very very dark but still on again?
 
D

dinan

Senior Member
Oct 28, 2008
942
47
About the "dots" or "spots" on the black screen - I've seen this on every SAMOLED screen and I suppose it's normal since you can't see it with the naked eye really. I've seen it myself with my naked eyes but it was tough... and you really have to look for it, I wouldn't be too concerned.

Also curious how the black minimum time and white minimum time are so similar?
 
D

Davidsmonkeyroost

Senior Member
Jun 30, 2007
53
76
Hertford
Hello all, So I've posted the results of stage 3 of 4 testing and it's interesting...

Let's compare Minimum brightness Black Screen with Minimum Brightness White screen.

Dim Black: 10h47 run time
Dim White: 10h20 run time

That's just a 4% improvement in run time by switching from a white screen to a black screen. That doesn't sound enough.

Looking at the Power split both times the power draw was 85% screen and 16% Android OS. I would have expected the Dim White to have a greater percentage Screen draw than the Dim Black.

So I can't explain it - Is the GPU counted in the "Screen" total? Is the MIPI controller converting the video signals into something the screen can display a power hog? Or is the power meter inaccurate? Dunno.

Anyone got their 2 pence/cents worth?

Hopefully the next test which is Full brightness Black Screen will show a bigger variance to Full Brightness White Screen. This would show that the the AMOLED part of the screen is the biggest draw when at full brightness. If it doesn't and the run time number is similar, then it's something else being very inefficient.
 
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    Davidsmonkeyroost
    Hello all,

    I've been suspicious of the power draw of the screen on the GNex, and so decided to figure out how much a difference brightness made.

    This is to test the difference extreme brightness settings make to battery run times. Including text, browsing or having radios on will dilute the results. I'm only interested in the efficiency of the screen and its supporting infrastructure people! :)

    Here's my testing method.

    1. Charge phone to 100% using a PCs USB charging (should give a more full charge than the wall adapters quick charge, I think, otherwise no harm done). Leave attached to USB cable
    2. Switch the phone into Airplane mode.
    3. Switch off Auto Brightness and turn brightness to Max
    4. Restart Phone. Leave it to settle for a few mins
    5. Fire up "Just Pictures" and the image "TotalWhite.jpg" (attached). No other photos in the folder where it sits.
    6. Disconnect USB charging
    7. Start Slide show. Record the start time.
    8. Every now and then (about 45 mins to an hour and bit) I quickly pop into settings and take a sneak look at charge level - don't want to get caught out!
    9. Resume Slide Show.
    10. Wait until the phone switches off, which is less than 2% charge
    ​

    Now, it's not a quick process as I'm going from 100% Batt until auto shut off. So I'll be updating this post in installments. Today is the Max Daddy Full Brightness White image!

    Full Brightness, White Image:
    100% 00h00m
    85% 00h39m
    60% 01h53m
    35% 03h08m
    0% 05h00m​

    Pretty good I think!

    Battery status stated that Screen was 91% and Android System was 9%. Screen on time was the same as the run time. It never went off.

    There's a heavy set of disclaimers to go with this though: The White Image isn't quite the right aspect for it to display across the full amount. Check out the image "White Full The Phone.jpg" - it's pretty close though. Just Pictures isn't so full screen that it takes over the Android buttons - Anyone know a 100% full screen picture view BTW? Between the point where it comes up with "Please connect your charger" (15%) and 6% it said that message over the White image and partly dimmed the screen - I'm at work and was in the middle of something when it happened.

    Minimum Brightness, Black Image:
    100% 00h00m
    85% 01h26m
    82% 02h05m
    18% 08h54m
    0% 10h47m​

    Battery status stated that Screen was 85% and Android System was 16%. Yes, that's 101%, but there you go... Screen on time was within a minute of the run time.

    Again, some notes on the testing: From the "connect your charger" point (i think 15%) to 8 % it had the message on the screen. Just before the end I accidently touched the screen and ended the slide show for up to 15 minutes and the screen went off. Switched it back on and it was at 2%. It then lasted something like 30 mins before auto shutdown. Black isn't Black! check out my the photo "Black Dim The Phone.jpg" - ignore the strange black specs, it was 1 seconds exposure at F1.4, with the camera facing down - think there's some crap in my camera body/lens.

    Minimum Brightness, White Image:
    100% 00h00m
    0% 10h20m​

    Again, Battery status stated that Screen was 85% and Android System was 16%. That's the same as when I ran it on Min Brightness, Black Image...

    Maximum Brightness, Black Image:
    100% 00h00m
    0% 10h52m​

    Battery status stated that Screen was 90% and Android System was 11% (again 101% also probably due to some rounding going on). Screen was on 100% of the time, Android OS was awake for 100% of the time, CPU time 23 Seconds

    Overview:
    Maximum Brightness White Image: 5h00m
    Maximum Brightness Black Image: 10h52m
    Minimum Brightness White Image: 10h20m
    Minimum Brightness Black Image: 10h47m

    Well, well, what's happened here? Maximum brightness with a black image scored the longest run time - unbelievable, right? Yeah pretty much: On the minimum brightness black run I did check the battery stats a few times. The black image run had a greater Android OS drain (11% vs 9%) compared to the white image. As I switch the phone off in preparation for the test it's possible I inadvertantly bump charged the phone. In addition to this, I was trusting the phone a lot more in this, the final test and didn't check the battery status near the end, so perhaps drawing a lower current happily sitting there doing nothing other than displaying a blank image the phone managed to syphon off the last dregs of power, as opposed to spending CPU time with me rummaging through the settings screens for battery stats. Let's put it all down to being in the margin of error and consider the Black images to have the same run times, despite the Android buttons blazing away on Bright (but they aren't many pixels).

    Conclusion:
    Back to my original concern, that the screen was abusing the battery more than necessary. I'm mostly happy with the outcome - Black bright and dim screens draw substantially less than a very bright white screen on this phone, as it should. It's surprising to see that on dimmest setting the white screen got so close to the run time of the black screens. It's producing a lot more light than either black screen. It's drawing c5% more power than the black screens, but I would expect a lot more. I'm guessing that the circuitry to run the Screen and the small amount of power used to make the "Black" OLEDs glow dark dark grey draws only a little less than the white screen.

    And that's a shame. I wanted to run an app such as "Off-Clock" to have a clock on the screen like the Nokia N8 used to do, but i'm thinking this will eat the battery in 10 hours 20 minutes. Only one way to know for sure....

    My initial annoyance that Black never is actually Black whilst the screen has faded. Many of you good folks have pointed out (and after more Googling) that all OLED screens have this, although the reason for it isn't clear. It's either to ease the transition from black to lit by having the LED at the threshold already, power seeping into the circuit somewhere or something else. Who knows, maybe we'd get better run times if the screen was on full brightness but used PWM or a fast strobe to show a dimmer image!

    That's all folks, discuss, and remember - continue testing...
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    2
    S
    Spybreak
    I love you for doing this. Please don't stop.
    View
    2
    D
    Davidsmonkeyroost
    Sorry guys, I messed up the Black Bright test. It was still running when I had to go to work and the power button must have been pressed when It was in my bag. Will re-run tonight.
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    M
    matt2053
    Guys, stop suggesting he use normal brightness settings or browse the web etc. That would introduce variables that would ruin the results. He's not testing to see how long the battery lasts. He's testing to see if white vs black display images affect battery life.

    Sent from my Galaxy Nexus using XDA App
    View
    1
    Nebucatnetzer
    Nebucatnetzer
    We we aren't criticizing you specific we just hijacked the thread a bit sorry for that :D.
    View

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