Aero and battery life

Aero and battery life

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Dwight Silverman, the tech reviewer at the Houston Chronicle, has written about the impact that the Aero theme has on battery life and performance (under the provocative title "Vista, Aero, battery life . . . and Doom" -- he's referring to the game Doom3, BTW).  It's a good post and I'd like to take a minute to expand on what Dwight has written.

First off, yes, as Dwight correctly points out, the Aero theme drives the GPU harder and therefore uses more power.  But in the big picture, it's really not that much more.  For example, the display on most laptops will consume somewhere between 15-25% of your "power budget" when you are running on battery.  Nevertheless, in our testing we've seen that turning on Aero consumes only about 1-4% more of battery life.  In terms of making your battery last longer, turning off Aero will not go very far while at the same time costing you some of the cool features that make Windows Vista fun to use, such as Flip 3D, taskbar previews, window transparency and so on.

Further, as Dwight correctly points out, your mileage can vary widely depending on the workload the machine is running (he uses the example of playing Doom3.)  To use an Aero-specific example, you would use more power enabling transparent window borders and stacking a lot of windows upon a portion of the screen showing a video clip.  The GPU would be required to constantly re-render those parts of the screen that make up the transparent window edges, which in turn drives the GPU harder.

Now, we know there are times when you want to fully maximize battery life and every little bit helps.  It's for this reason that we automatically turn off things like window transparency when the machine is put into a power-saving profile.  We don't turn off Aero wholesale because in the end, doing so is not going to save you much more power.  So we turn off the transparency effects and maintain a smooth user experience.  We know that it results in a tradeoff, but we also think it's a fair one to make.

P.S.  As an aside, I recently learned that testing the impact of software features on battery life is exceptionally tricky, even by benchmarking standards.  A huge number of variables must be controlled for.  In fact, something as simple as the way a battery is handled can introduce enough variability into testing to make it difficult to identify the true cause of any observed changes in performance or battery life.  This is because the charge a battery requires can vary considerably based on, among other things, the battery technology (Li-poly, Li-ion, Ni-MH, etc.), how recently the battery was power-cycled, how old the battery is, and even the temperature of the battery when it was charged.  Wow.

11 Comments
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  • Does Aero allow for the colour of the taskbar and start menu to change? so far window borders and transparency is all I can change, does the taskbar and start menue always stay dark or near black?, personally I would like the taskbar and start menu to actually match the colour picker/theme.

    Unless I have missed something?

  • need charge the battery!

    http://www.rechargeable-battery.us

  • battery
    1 Posts

    I guess you can join worldwide battery resources http://www.global-battery-directory.com to gain more help.

  • Gallus
    2 Posts

    I personally have two user accounts for line power and mobile, my laptop has decent (new, but cheap) specifications. The mobile profile has all but essential services and auto-run programs set to manual startup, while the line power one has everything turned to the 'on' position, the difference in battery life between the two is around one hour. For me thats one hour longer to enter data in the field, even without the pretty effects, it is worth it.

  • caywen
    24 Posts

    I want to believe this, but this just has not been my experience with Vista. Honestly, when I ran XP on my HP DV9000T (1.5GB, Core Duo) I got about 3 hours of battery life. After upgrading to Vista, I get about 1.5 hours tops. After disabling Aero Glass, I get about 2 hours (so definitely there are other things going on given that I'm still short an hour). But something Aero-related gives me 33% more battery life.

    Another thing I noticed is that my laptop *bakes* when Aero Glass (or should I call it Desktop Composition?) is turned on. The fan runs almost nonstop. With it turned off, the fan is much more reasonable and the machine is only moderately warm.

    I understand that from your perspective, you can't see why this would happen, but it is and it's really killing my Vista experience.

  • In testing a change to a handheld application running on Windows Mobile, we found that moving from a polling loop (containing a Sleep call) to blocking on an event actually had an almost unmeasurable effect on power consumption and hence battery life. The main consumer of power on the device was the screen backlight!

    If you want to save power, turn down the backlight.

  • tamir
    3 Posts

    As promised earlier, I have a comparition done, you can find it in my blog here http://blogs.microsoft.co.il/blogs/tamir/archive/2007/05/15/Vista-drain-a-battery_2100_-and-Vista-Battery-Saver-is-very-useful.aspx

  • jchandler
    13 Posts

    I am stuck between whether or not to disable Aero half the time, because sometimes the graphical effects can be a big burden on your battery. But you know hopefully companies will provide better solutions for Windows Vista to help increase battery life.

    All the best

    Josh Chandler

    http://www.windows-media-player-updates.com

  • I involuntarily found an easy way to compare battery life:

    I just installed Vista on my notebook (Samsung X20) which previously ran XP.

    Using XP my battery lastet up to three hours.

    Using Vista my battery lasts little more than one hour.

    This is the very same notebook, the very same battery. The same hardware, the same tasks. I even installed the same apps again.

    It does not matter to me (much), usually my battery is shelved and I run from a powerline, but still it is quite a difference.

    As far as I read this is because the bios of my notebook needs to be optimized for vista, but since I don't really care I have not looked for an update yet.

  • Wireless is more of a battery killer imho.

  • tamir
    3 Posts

    I completely agree with you, however, it seemed, that "fun things" such as aero, sidebar, indexing service etc. "eats" need much more power then in previouse OSes. I wrote small utility, that optionaly disables those features and the idea is to add there (or just run externally) kind of tests to proof my statement.