Is your wallpaper draining your battery? Tip

[zephryn]

Source: 4People Software

I, like many members here, have had limited success with getting my battery lasting as long as my previous Bold, a 9780. I considered myself one of the lucky ones: I didn't have a faulty battery, or parts of the chassis lifting up, or a yellow screen, but I was used to a comfortable 2 day battery. My 9900 will last for more than a day easy, and I COULD squeeze 48 hours out of it if I wanted to, but I've found that when you're in a situation where you need it to last for 2 days, you're probably using it slightly more than usual...at least I do anyway, so I've been researching every battery saving tip I could find. Lo and behold, I discover the 4People Software blog with an interesting finding on how OS7 handles wallpapers.

TLR version: Only native resolution wallpapers (640x480 for the 9900).

The writer found that under Application Management, his Homescreen was using more cpu over the course of the day than expected. He was using a custom wallpaper that was larger than the native resolution of his display, so he tried setting the wallpaper to one of the default images, and his battery life improved.

One theory is that with larger images, OS7 downscales every time it's called to the forefront (every time you go to your homescreen). OS6 and earlier devices, I'm assuming, just saved a copy of your homescreen image in the correct format and dimensions, and that's that.

So does it work? Yesterday after reading that post I re-sized the 800x600 image that I had been using since I got my 9900. This morning just before 8am I took it off the charging dock, verified I was at 100%, and didn't give it another thought. It's now almost 4pm and my battery is 90% full. (using Options reading) What's more is that it was showing 95% while I was doing some web browsing around 2pm, and dropped to 90% when I was done, so technically you could say it's down to ~92% This is around a 50% increase in battery life as I have had the past few weeks.

Now before you start jumping for joy, I'm not a heavy user. I've had a couple text conversations this morning, some browsing, and keeping up on my Facebook and Twitter feeds probably once every hour or so. Hopefully the real power users will get some more accurate data.

[Spartacus_82]

Originally Posted by zephryn

Source: 4People Software

I, like many members here, have had limited success with getting my battery lasting as long as my previous Bold, a 9780. I considered myself one of the lucky ones: I didn't have a faulty battery, or parts of the chassis lifting up, or a yellow screen, but I was used to a comfortable 2 day battery. My 9900 will last for more than a day easy, and I COULD squeeze 48 hours out of it if I wanted to, but I've found that when you're in a situation where you need it to last for 2 days, you're probably using it slightly more than usual...at least I do anyway, so I've been researching every battery saving tip I could find. Lo and behold, I discover the 4People Software blog with an interesting finding on how OS7 handles wallpapers.

TLR version: Only native resolution wallpapers (640x480 for the 9900).

The writer found that under Application Management, his Homescreen was using more cpu over the course of the day than expected. He was using a custom wallpaper that was larger than the native resolution of his display, so he tried setting the wallpaper to one of the default images, and his battery life improved.

One theory is that with larger images, OS7 downscales every time it's called to the forefront (every time you go to your homescreen). OS6 and earlier devices, I'm assuming, just saved a copy of your homescreen image in the correct format and dimensions, and that's that.

So does it work? Yesterday after reading that post I re-sized the 800x600 image that I had been using since I got my 9900. This morning just before 8am I took it off the charging dock, verified I was at 100%, and didn't give it another thought. It's now almost 4pm and my battery is 90% full. (using Options reading) What's more is that it was showing 95% while I was doing some web browsing around 2pm, and dropped to 90% when I was done, so technically you could say it's down to ~92% This is around a 50% increase in battery life as I have had the past few weeks.

Now before you start jumping for joy, I'm not a heavy user. I've had a couple text conversations this morning, some browsing, and keeping up on my Facebook and Twitter feeds probably once every hour or so. Hopefully the real power users will get some more accurate data.

You're probably right about the size of the wallpaper matter. Apart from that I can tell you that you can only be happy and satisfied about your battery life most of us have to recharge phone two three times in a day. Even if the 9780 is a far more hard working phone as I stated on other postes before didn't never last me for two three day unless I wouldn't have used it.
With my normal usage though which is
60/70 minutes of phone calls most of the time the phone is BT connected to my car
Streaming music at the same time
Browsing and tons of e mail incoming and outcoming
BBM

With 9780 I would have done the day and night maybe but with 9900 I have to plug after lunch especially the drain during calls is tremendously managed comapred to the previous phones. 14/18 % discharge rate. I had 2 9900 and both acted the same. The only time I could get a 1.6% or a 2.2 was on hidle with a good signal coverage on 3G.

A more performant powerful car requires more petrol and most of all a bigger tank otherwise you have to stop many times at the petrol station .
That is what is happening to most of us due to a smaller battery also. And what I can accept is the no autofocusing camera so nice on my 9700 &9780 to take scannies with.

Posted from my CrackBerry at wapforums.crackberry.com

[Phill_UK]

Sorry to say, but I think that wallpaper theory is utter BS.

Once an image is scaled to fit your screen, it is saved in a wallpaper.dat file under Store/appdata/rim/homescreen. It is that scaled down image file that is used for your homescreen wallpaper, not the original oversized image. The original image can be deleted from your phone, and your wallpaper will still remain. The wallpaper.dat file is only a few kb in size, and uses virtually no processing power... and thus uses virtually no battery power.

Posted from my CrackBerry at wapforums.crackberry.com

[Heavy Fluid]

I am thinking that I agree with Phil_UK on this one.

[Spartacus_82]

Originally Posted by Phill_UK

Sorry to say, but I think that wallpaper theory is utter BS.

Once an image is scaled to fit your screen, it is saved in a wallpaper.dat file under Store/appdata/rim/homescreen. It is that scaled down image file that is used for your homescreen wallpaper, not the original oversized image. The original image can be deleted from your phone, and your wallpaper will still remain. The wallpaper.dat file is only a few kb in size, and uses virtually no processing power... and thus uses virtually no battery power.

Posted from my CrackBerry at wapforums.crackberry.com

I heard that one from you before regarding OS 5 and 6 Phil. I didn't know was the same on OS 7 as well. I believed what OP was saying even because I didn't have enough time to spend with my new devices FFS! Someone here knows more than me to so hats down. Precise and accurate as always Phill

Posted from my CrackBerry at wapforums.crackberry.com

[pfiffi78]

Originally Posted by Phill_UK

Sorry to say, but I think that wallpaper theory is utter BS.

Once an image is scaled to fit your screen, it is saved in a wallpaper.dat file under Store/appdata/rim/homescreen. It is that scaled down image file that is used for your homescreen wallpaper, not the original oversized image. The original image can be deleted from your phone, and your wallpaper will still remain. The wallpaper.dat file is only a few kb in size, and uses virtually no processing power... and thus uses virtually no battery power.

Hmm, I don't think it's such utter BS. The observation they describe is plausible. They also say that this was all working fine in pre OS 7 releases.

zephryn seems to see already see some effects.

I do software for living myself and I know that there is no bug free software no matter how much you try you will always find something. And yes, it can also happen that you break something that previously worked.

So it could easily be that the code that generates the wallpaper.dat file is still in place and called but that there may well also still be some code (maybe from testing), that does something else, here the scaling, which eats up CPU time.

How else do you explain the observation made that every time a custom wallpaper is being set the batter runs out quicker than when one is set that matches the screens native resolution?

I think people need to try it out themselves and then we'll see if there is something to it or if it's 'utter BS' as you claim.

[Phill_UK]

Originally Posted by pfiffi78

Hmm, I don't think it's such utter BS. The observation they describe is plausible. They also say that this was all working fine in pre OS 7 releases.

zephryn seems to see already see some effects.

I do software for living myself and I know that there is no bug free software no matter how much you try you will always find something. And yes, it can also happen that you break something that previously worked.

So it could easily be that the code that generates the wallpaper.dat file is still in place and called but that there may well also still be some code (maybe from testing), that does something else, here the scaling, which eats up CPU time.

How else do you explain the observation made that every time a custom wallpaper is being set the batter runs out quicker than when one is set that matches the screens native resolution?

I think people need to try it out themselves and then we'll see if there is something to it or if it's 'utter BS' as you claim.

Ok, maybe 'utter BS' was a tad strong, but I did say 'I think...' in offering my opinion.

You're welcome to disagree and offer your own opinion, but I'm still not buying that theory.

I've always used the same oversized wallpaper on my berries (4931x3698 pixels), and have never had battery issues relating to this.

Just to prove, here's a capture of my Homescreen app CPU usage...



Virtually no action there to show increased battery consumption.

Posted from my CrackBerry at wapforums.crackberry.com

[zephryn]

Good points. I'm a bit skeptical about the findings myself, although 80% remaining after 13 hours today is interesting to say the least. All I know is that today I have better battery life than all other days I've had this phone. I've checked my homescreen usage (same location as Phil's image). And my numbers aren't much higher. 1m9s for today and 2m1s yesterday. So I'm thinking wallpaper handling has more roots than simply the homescreen app, assuming this isn't merely a coincidence of course.

The point about wallpaper.dat does make me think...I remember having a corrupted microsd card before and my custom wallpaper disappeared until I got the card reformatted and re-selected my wallpaper image. If wallpaper.dat is stored in flash then it would stand to reason that the image would remain regardless of the card situation. Has anyone removed their microsd card and rebooted their phone and found the wallpaper reset?

[melander]

Did the rescale darken the image such that less power is needed to display bright colors?

[zephryn]

No darkening was detected, and in practice it wouldn't make any difference anyway as the 9900 uses a type of LCD screen. Only the newer OLED based screens save energy with darker colours.

[Masahiro]

If the wallpaper is modified every time the home screen comes up, wouldn't it be easy to test this theory out by mashing the home screen key and pressing an icon over and over again? I mean, if that alone affects battery life dramatically throughout the day, then it should be easy to spot any differences.

Posted from my CrackBerry at wapforums.crackberry.com

[zephryn]

Unfortunately the act of opening up any app to go full screen would also require cpu work, which would drain the battery in itself, leading to false positives.

Posted from my CrackBerry at wapforums.crackberry.com

[Boldover]

If the wallpaper photo is being stored on the memory card vs the device memory, will that affect battery life as well?

I wonder. I will give that a try and see. I believe, that on my old Bold 9000, that seemed to help. Not sure on the current 9900 though. I upgraded to a new OS, .503(?) and battery was great...until I added whatsapp, but even after removing whatsapp, poor battery life....10-14% discharge rate....

[dimm0k]

Originally Posted by Phill_UK

Sorry to say, but I think that wallpaper theory is utter BS.

Once an image is scaled to fit your screen, it is saved in a wallpaper.dat file under Store/appdata/rim/homescreen. It is that scaled down image file that is used for your homescreen wallpaper, not the original oversized image. The original image can be deleted from your phone, and your wallpaper will still remain. The wallpaper.dat file is only a few kb in size, and uses virtually no processing power... and thus uses virtually no battery power.

Posted from my CrackBerry at wapforums.crackberry.com

where exactly do you find this Store/appdata/rim/homescreen under OS7?