Database Users

Why does "Display" use so much power?

My phone is off a lot of the time but it still uses up a lot of my power according to the battery use screen.
For example, right now my battery is at 45%, 9h 15m since unplugged. "Display" shows up at 48% of the power use. Time on is 58m. On my old Evo, Display was rarely on the top of the list. A day like today would have Cell Standby and Phone Idle at the top taking up over 50 - 60%.
Could it be the auto brightness setting that's sucking power? Anyone else getting these results?

I haven't had the time to try and figure out why, but yes, I am getting the same results on mine as well. Right now the battery is at 44% (9h 42m on), with the Display at 55% (1h 33m display on). Display has always been at the top of the list for me. The next three are Android OS 13% (1h), Cell Standby 13% (9h 42m), Phone Idle 8% (8h 14m)

Mine has been unplugged for about 1.5 hrs, and on for 35 minutes.
Voice Calls: 45%
Display: 33%
Cell Standby: 8%

I'm experiencing something similar. Gravis, are you on auto brightness? If not, what brightness level?

nick_karstedt said:
I'm experiencing something similar. Gravis, are you on auto brightness? If not, what brightness level?
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I use a power widget to scale my screen brightness as needed. I'm usually on the lowest setting since I'm mostly indoors but I had it on 100% all day yesterday since I was outside and it wasn't really draining my battery.

gravis86 said:
I use a power widget to scale my screen brightness as needed. I'm usually on the lowest setting since I'm mostly indoors but I had it on 100% all day yesterday since I was outside and it wasn't really draining my battery.
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I too keep mine on the lowest setting as well. It's plenty bright enough for me. Also, I wouldn't trust those readings...it could also be related to the whole false reading of the reception and battery status symbol. Perhaps software related. Nevertheless, the screen still uses 20% less power than traditional lcd's.
Try keeping it off auto brightness and see how it does...should notice an improvement.

iunlock said:
I too keep mine on the lowest setting as well. It's plenty bright enough for me. Also, I wouldn't trust those readings...it could also be related to the whole false reading of the reception and battery status symbol. Perhaps software related. Nevertheless, the screen still uses 20% less power than traditional lcd's.
Try keeping it off auto brightness and see how it does...should notice an improvement.
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You mean 20% less then an average AMOLED? and then AMOLED is 30-40% over LCD

Guys... You WANT your screen to be the highest thing using battery. It doesn't mean that it is bad. It just means that the screen is taking MORE battery than other things. You need to take it for what it is. A comparison versus other items on the phone. Your screen using that much power is how it should be (think about your laptop... turn the screen down or off, battery goes right up). If your screen was at the bottom, it would mean that the actual PHONE was using a ton more power.

hah2110 said:
Guys... You WANT your screen to be the highest thing using battery. It doesn't mean that it is bad. It just means that the screen is taking MORE battery than other things. You need to take it for what it is. A comparison versus other items on the phone. Your screen using that much power is how it should be (think about your laptop... turn the screen down or off, battery goes right up). If your screen was at the bottom, it would mean that the actual PHONE was using a ton more power.
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Good point. I'd rather have the screen eating power than say, the GPS. But I guess as long as the phone gets you through the it doesn't really matter, does it?

Does turning off the "Powering saving mode" option under "Sound and display" seem to help or hurt the situation?

AVonGauss said:
Does turning off the "Powering saving mode" option under "Sound and display" seem to help or hurt the situation?
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Mine is off. I don't like the screen changing intensity/brightness without my permission

AVonGauss said:
Does turning off the "Powering saving mode" option under "Sound and display" seem to help or hurt the situation?
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I shudder to think that a "power saving" mode would actually increase battery usage...

gTen said:
You mean 20% less then an average AMOLED? and then AMOLED is 30-40% over LCD
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Indeed.

Most of the GSM models have display at the top, while CDMA have standby and idle.
This is due to CDMA radios drawing a lot more power.

I too am experiencing the same thing... my battery life has been less than stellar, so I have taken it off auto-brightness and am using a black wallpaper to try and reduce the consumption. After being on for 4 hours, (I had to reboot several times this afternoon) my display has used 70%, the next down is cell stanby at 12% I was fully charged at 3:30 today - it is now 10 and I am down to 33% battery remaining, with moderate to minimal usage.
I guess a gorgeous display requires a lot of battery.....

Battery use has to add up to 100%, so something has to take a majority. 66% doesn't mean it took a huge part of your battery. Imagine this, you unplug your phone and then go on pandora for 15 minutes of the first 20 minutes unplugged. Say your battery was at 96ish by then. If you checked your battery usage and it said something like PANDORA: 75%, it means that pandora used 75% of the 4% that has been drained, not like pandora has some type of abnormal battery sucking bug in it (key word abnormal, i'm aware pandora wears on a battery). But get the gist? If it were "cell standby" and "phone idle" that were using the battery, then we'd have something to worry about seeing as the phone wouldn't even be in use during its times of most power consumption.

You people apparently never actually TALK on your phone. My voice calls take most of my power.

Pneumatic said:
You people apparently never actually TALK on your phone. My voice calls take most of my power.
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for me, i've noticed that installing and moving files on the internal and sdcard memery eats up the battery the fastest.

hah2110 said:
Guys... You WANT your screen to be the highest thing using battery. It doesn't mean that it is bad. It just means that the screen is taking MORE battery than other things. You need to take it for what it is. A comparison versus other items on the phone. Your screen using that much power is how it should be (think about your laptop... turn the screen down or off, battery goes right up). If your screen was at the bottom, it would mean that the actual PHONE was using a ton more power.
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Click to collapse
hah2110 said:
Guys... You WANT your screen to be the highest thing using battery. It doesn't mean that it is bad. It just means that the screen is taking MORE battery than other things. You need to take it for what it is. A comparison versus other items on the phone. Your screen using that much power is how it should be (think about your laptop... turn the screen down or off, battery goes right up). If your screen was at the bottom, it would mean that the actual PHONE was using a ton more power.
Click to expand...
Click to collapse
hah2110 said:
Guys... You WANT your screen to be the highest thing using battery. It doesn't mean that it is bad. It just means that the screen is taking MORE battery than other things. You need to take it for what it is. A comparison versus other items on the phone. Your screen using that much power is how it should be (think about your laptop... turn the screen down or off, battery goes right up). If your screen was at the bottom, it would mean that the actual PHONE was using a ton more power.
Click to expand...
Click to collapse
hah2110 said:
Guys... You WANT your screen to be the highest thing using battery. It doesn't mean that it is bad. It just means that the screen is taking MORE battery than other things. You need to take it for what it is. A comparison versus other items on the phone. Your screen using that much power is how it should be (think about your laptop... turn the screen down or off, battery goes right up). If your screen was at the bottom, it would mean that the actual PHONE was using a ton more power.
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I can't quote this enough for emphasis.
Use your brains folks. If your battery is lasting all day and your screen is using half of your power draw, then you simply have a far more efficient phone than before.
And over the EVO, that makes a TON of sense. Your WiMax OFDM radio probably used up a higher percentage of your total power draw because it simply uses more power than our WCDMA UMTS radio.
Be happy - not disappointed. It means your battery is mostly being used up only when you actually use the phone as opposed to eating up all of your battery while it's just sitting in your pocket.

reuthermonkey said:
I can't quote this enough for emphasis.
Use your brains folks. If your battery is lasting all day and your screen is using half of your power draw, then you simply have a far more efficient phone than before.
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Rather than wasting time with not so clever posts, maybe it would be more beneficial to read the first post a bit closer. If you're not using the device a lot, you would expect the Display usage indicator to decrease over time and the other indicators such as Cell standby and Phone idle to increase over that same time period.

How much energy does the screen use?

I'm down to 15% and It says its been on for 1 hour 30 minutes while my phones been unplugged for 9 hours and 30 minutes, but it used 68% of battery? Is the screen the biggest battery hog?
My tws is 11%
Sent from my SPH-D700 using XDA App

All of it.

gophergun said:
All of it.
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pretty much.

Screen use always tops my battery use by a large large large margin.

I always thought the AMOLED screens were supposed to be super battery efficient, but it always seems like its the thing totally KILLING battery life. Compared the battery usage to an evo with a standard LCD screen and even though its larger, it uses vastly less power.

I owned the EVO before and while I was thinking about getting the epic, I read a lot about AMOLED technology. I posted a bunch in July about my findings.
Regarding Power Consumption I posted this in July:
http://forum.xda-developers.com/showthread.php?p=7271721#post7271721
http://forum.xda-developers.com/showthread.php?p=7403102#post7403102
It turns out that AMOLED uses 3 times as much power as LCD when displaying text on white backgrounds...ouch. I stand by my decision to purchase the Epic however. The Battery life is actually a little better than what I got on the EVO.

muyoso said:
I always thought the AMOLED screens were supposed to be super battery efficient, but it always seems like its the thing totally KILLING battery life. Compared the battery usage to an evo with a standard LCD screen and even though its larger, it uses vastly less power.
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They are for the most part, and there's more progress to be made in those regards, but it's conditional. For all white, it can uses more power, for something like watching a movie, the AMOLED wins. I think part of it, though, is that the rest of the phone is just ridiculously efficient. Either way, it looks fantastic.

Power saving mode

So, this has been discussed elsewhere but i believe needs to be examined with the tab.
From what i understand, the setting (and cpu-enthusiastic service, i assume) will be of most benefit to OLED screens like those on the galaxy phones. Also, i would to assume that because there are a lot of white backgrounds in general tablet usage, the contrast and fullscreen backlight adjustment it makes would actually lower battery life on a IPS display.
I have noticed an improvement over the last 24 hours. Do you guys have any thoughts on this?
EDIT: i have just done some testing and the power saving mode does seem to help on the ips display. After keeping it off all day yesterday i managed an extra hour at least... it died at 7 (about 8 hours light use), while on saturday i got about 6 after getting up at the same time.

Graphical Analysis on Battery (3G vs WiFi, Black vs White, etc)

I was able to add some real time graphing to the battery calibrator app where the current draw thru the battery is sampled every 2 seconds. This gives a very fine tuned accurate picture of what the battery is doing. note the battery driver had to be edited to allow for current readings taken at a faster sample rate, so all that work was done initially.
This first test is the phone switching from connected to 3G to switching over to wifi. notice the extreme difference between the spikes and then how smoooth it levels off around the 14 second mark. shows how much battery is saved using wifi (i'll come to this more later).
Switch from 3G to WiFi data by RogerPodacter
The second image is just showing the phone left completely idle 3g data, but with the screen on, min brightness, and timeout set to never. curious to see those regular periodic blips of current draw. notice -170mA is about spot on for the black amoled screen showing all black color like that. and this shows how efficient 3g data is during idle when no data transfer is taking place. This graph view is what was displayed during this time, mostly black.
Idle 3G Connection, Screen on Min Brightness by RogerPodacter, on Flickr
the next screen shot shows switching from screen brightness at minimum to maximum brightness, but showing the same black graph image. notice the slight increase, but it stays dead flat still. it switched at the 36 second mark.
Switch from Min to Max Brightness, Showing Black by RogerPodacter, on Flickr
This screen shot shows what happens to amoled when displaying a fully white image at maximum brightness. the power draw goes thru the roof! it started at the 16 second mark. i used the app "dead pixel detect" to display solid full screen colors, this one showing white.
Displaying a Solid White Screen by RogerPodacter, on Flickr
Same as above, but now switching back to the black graph view, the current drops down to normal. Swtich happened at about the 15 second mark.
White Color Max Brightness by RogerPodacter, on Flickr
The next screen shot shows why wifi gives so much better battery life. this shot shows receiving a new gmail email message over 3g data connection. right at the 20 second mark the email comes in, and the current draw spikes over -500mA. when the same email message is received while connected to wifi, there is not even a spike at all, it stays flat.
Receive Email over 3G by RogerPodacter, on Flickr
This is due to the much faster latency that comes with wifi. on 3g, the 200ms ping time, each direction to and from the server, all while the radio is fired up, is what causes the spike. now think about that happening all day long with all your google services constantly talking to their servers.
This next one shows loading a web page with a light color, and scrolling around. I loaded a thread here at XDA with the stock browser, without invert color turned on. look at the enormous spikes.
Load and SCroll Light Color web page by RogerPodacter, on Flickr
And finally, this is loading and scrolling the same web page, same thread, but with invert color option turned on, so the color was basically black and dark. (For these last 2 web page tests, i forgot to turn the screen brightness back from max to minimum brightness. oh well.).
Load and Scroll Dark color web page by RogerPodacter, on Flickr
If anyone wants more test comparisons done, just post your request. For the above tests, i didnt think things out too much, so i'd like to really do things over and show more/better scenarios of how power draw is effecting our phones' battery.

Interesting! Thanks for taking the time to put this together.

I had one more, from today. Watch what happens when i go and read a topic on the engadget app (entire white colors) while i was outside at max brightness. power draw sky rockets up, then back down when i return to the black graph view.
Browse the White color Engadget App by RogerPodacter, on Flickr

great data - can you check some apps, like words with friends & weather channel (background widget). words with friends tops out my cpu for no good reason.

fyid said:
great data - can you check some apps, like words with friends & weather channel (background widget). words with friends tops out my cpu for no good reason.
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how exactly would you like it tested? i've never used words with friends, and i never installed the weather channel widget either. the second one might be harder to test. is there a way to tell it to initiate its update or data transfer or whatever it is that it does?

The current graph is a lil bit confussing. Is the rightmost the oldest plot? and the leftmost is the most recent?

zeus_chingon said:
The current graph is a lil bit confussing. Is the rightmost the oldest plot? and the leftmost is the most recent?
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The right direction is older and the left is more recent. The full current graph only shows in seconds, around a minute or so. So this is like a true profile of all power, in real time, going thru the battery's resistor, and hence device power draw. So its great to see exactly what different tasks do to power behind the scenes.
I've been doing many more tests just for fun. My overall discovery is that the screen is bad, real bad, and there's a disproportionate difference between min and max screen brightness. Min is really good, but max is so far off the charts bad that its horribly power hungry. So I'm practicing keeping locked at min brightness. Then comparing things like CPU usage loading a web page in the background, then over WiFi then 3g, etc.
I'm enjoying seeing the bad offenders.

Thanks for posting these, you're just as helpful here as you were on the S60 boards @ hofo

Excellent analysis to visually confirm what has been known and constantly overlooked by people complaining about their battery life: the 2 major power-hungry things in the phone are the display and the 3G data - when it fires up.
You could also show GPS power draw, to have a good comparison between values. I'd guess that running Google Maps on full brightness during the day over cellular data will show near the maximal power draw possible from the device.

Jack_R1 said:
Excellent analysis to visually confirm what has been known and constantly overlooked by people complaining about their battery life: the 2 major power-hungry things in the phone are the display and the 3G data - when it fires up.
You could also show GPS power draw, to have a good comparison between values. I'd guess that running Google Maps on full brightness during the day over cellular data will show near the maximal power draw possible from the device.
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Good ideas, I'll do a gps test next. I've already done it but with no screen shots, and I can say it really puts I high load on the battery by far.
I also just now did a 3g phone call test, and it was higher than I thought it would be. I'll post the screen later.
I'm now a huge proponent of min screen brightness. If you can use min brightness then do it. If that's too dim during the day then 40% gives the best combo of still usable with decent power. But auto brightness, or max brightness which will happen in sun light, is just totally off the charts bad. And when loading a web page outside at max brightness, the power is thru the roof.
So I'm now locking my screen at 40%.
Edit: I also did color comparisons. Full screen of white, red, blue and green. Nothing too crazy but still cool.

Fascinating read. Keep up the good work!

Wow, very interesting.
Thanks man.

Wow I'm finally trying out stock gingerbread and the idle power readings are significantly lower than froyo. On froyo I'd see around 20mA and I'm seeing about 7mA now consistently. My app doesn't work on stock so I don't have fine control but it definitely makes sense from reading what people are saying.

Nice little review.
Out of curiosity, do you think there's much difference between AMOLED, SAMOLED and SAMOLED+ in terms of power consumption?
I'm eyeing the Galaxy S II as my next phone and online reviews all rave about how power efficient it is. But we all know how that isn't entirely true!

The SAMOLED displays are supposed to be 30% more efficient then regular AMOLED.

Hmm, and I have a Nexus S, and that SAMOLED seems to be total crap... lol

tangcla said:
Nice little review.
Out of curiosity, do you think there's much difference between AMOLED, SAMOLED and SAMOLED+ in terms of power consumption?
I'm eyeing the Galaxy S II as my next phone and online reviews all rave about how power efficient it is. But we all know how that isn't entirely true!
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Samsung claims a 30% increase in power savings, bit I don't believe it for a second and here's why.
First, both the nexus one (amoled) and nexus s (super amoled) both get IDENTICAL browsing test results, both make it 3.7 hours at anandtech. Nexus s has slightly larger screen but also has larger battery.
Second all you have to do is look thru galaxy, nexus s, and galaxy s2 forum. Not a single one has anyone getting more than 4 hours of screen on time in the battery threads. Not a single bit of improvement, at all, between the amoled technologies.
Then to rub it in, iPhone 4 crushes it getting a full 10 hours of browsing time on the same test.
LCD is becoming my preferred choice more and more. Testing an HTC inspire with slcd, it pulls 250 mA Max brightness. But my test results in this thread alone shoot up to 900 mA just loading white pages.

Hmm. So wonder whether it's worth getting the HTC Sensation instead of the Galaxy S2...

Wow! With full brightness on a mear-white page and the torch on, I was drawing 747mAH...

Radio versions
There were conflicting reports about power consumption of various radio versions including versions 5.08 and 5.12. It would nice to see a more solid evidence of how these radios perform. Thanks ...

efficiency of ambient display, adaptive brightness and black ui on Amoled

hey, i want to know if these 3 features drain battery or aid in better battery life
ambient display - i know it's an amoled so only few pixels are turned on, but what i want to know is do people face a much better battery life with this feature turned on and by that i mean like a significant difference, same with adaptive brightness as compared to toggling it yourself. And lastly black color on amoled screens, how much difference in battery life can you get approximately by using a black ui throughout, like 10% or 25% ?

the battery improvements are not noticeable. even in a full black background, but that's just my experience.

rrohanjs said:
hey, i want to know if these 3 features drain battery or aid in better battery life
ambient display - i know it's an amoled so only few pixels are turned on, but what i want to know is do people face a much better battery life with this feature turned on and by that i mean like a significant difference, same with adaptive brightness as compared to toggling it yourself. And lastly black color on amoled screens, how much difference in battery life can you get approximately by using a black ui throughout, like 10% or 25% ?
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Honestly, the gains in battery life from using a black background would be pretty small in my opinion. I don't see how using ambient display would save any battery at all, as opposed to what? The biggest gain would be adjusting brightness manually instead of using adaptive brightness, adaptive brightness can be pretty heavy on the sensors.

Heisenberg said:
Honestly, the gains in battery life from using a black background would be pretty small in my opinion. I don't see how using ambient display would save any battery at all, as opposed to what? The biggest gain would be adjusting brightness manually instead of using adaptive brightness, adaptive brightness can be pretty heavy on the sensors.
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I'm trying to compare ambient display to constantly unlocking the phone to check for the time or notifications

rrohanjs said:
I'm trying to compare ambient display to constantly unlocking the phone to check for the time or notifications
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In that case I believe using ambient display would be the best option.