Battery Life: Take Two Steps Forward, and Two Steps Back

If we look at the power consumption comparison we did in our GeForce 9300 review you'll see that the NVIDIA chipset pulls around 10W less power than G35 at idle, extending up to 15W under gaming loads. NVIDIA's 65nm GeForce 9400M used in the new MacBook and MacBook Pro is effectively the same chipset and thus it's safe to assume that there's a healthy reduction in platform power consumption afforded by the new hardware.

Apple reduced the capacity of both the MacBook and MacBook Pro batteries by 10W (60WHr down to 50WHr for the Pro and 55WHr down to 45WHr for the standard MB). Given that total platform power consumption should go down by around 10W, Apple's efforts here seem to make perfect sense. Smaller batteries mean lighter and potentially thinner notebooks; unfortunately it also means that battery life won't improve at all.

To test this theory I ran two of the battery tests I did back when the first Penryn MacBooks launched:

Battery Life: Wireless Web Browsing

The web browsing test shows that the MacBook Pro battery life remains basically unchanged, while the MacBook takes a slight hit compared to its predecessor. For all intents and purposes, these notebooks won't last any longer than the old ones.

The same thing is true about the heavy usage scenario: battery life basically remains unchanged:

Battery Life: Heavy Downloading + XviD + Web

Note that in both of these tests the MacBook Pro's GeForce 9600M GPU was disabled and only the chipset's internal GeForce 9400M was used. Apple indicates that you lose 20% of your battery life if you use the 9600M on the MacBook Pro; to test this I ran the heavy usage scenario benchmark but with the 9600M enabled:

  GeForce 9600M Disabled GeForce 9600M Enabled
Battery Life (Heavy Usage Test) 3.13 hours 2.37 hours

 

Using the dGPU dropped battery life by 24%, which is close enough to Apple's numbers to call them relatively honest. I also appreciate that Apple's 5 hour battery life is about what I got with the MacBook Pro in my web browsing test. Honesty is very important in any relationship, even if it's one between a manufacturer and a consumer.

GPU Accelerated H.264 Decode The Unexpected: Battery Life in OS X vs. Windows Vista
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  • Calin - Friday, October 24, 2008 - link

    What about testing power use under XP I mean
    XP compares more favourably to Mac OS (or anything else) than Vista, and I wanted to know if that excessive power use is Vista-only, or if it does appear on Windows XP too
  • strikeback03 - Thursday, October 23, 2008 - link

    Or some version of Linux?
  • wilkinb - Wednesday, October 22, 2008 - link

    yeh I agree the diff will be how the OS is set to manage each device etc etc...

    On my Sony laptop i get around 2 hours on high performance and a bit over 5 hours on battery saving...

    The results they posted dont really tell us much other then a bootcamp vista install isnt as good as an osx install at managing power on apple laptop... amazing right?

    I am sure if i dont use the Sony install and tool/drviers etc I will also get less battery life on my laptop. So the question would be do you think apple put more effort into power management on their OSX install then they did for Vista?
  • JarredWalton - Wednesday, October 22, 2008 - link

    Let me just say that I've tried testing various power saver setting under Vista on several notebooks (see review on Friday) and I just can't get anywhere near 5 hours of battery life. Sure, the CPUs are a bit higher spec on some of the notebooks, but as one example a 12.1" laptop with 55 Whr battery, 320GB 5400RPM HDD, 4GB RAM, LED backlighting, and P8400 pulls an "amazing" 138 minutes of DVD playback and 142 minutes of web surfing... though it does manage 261 minutes when sitting idle at the desktop.

    As best I can tell, the CPU and HDD just don't seem to be entering sleep modes much if at all, unless the system is 100% idle. Even then, 261 minutes idle battery life doesn't compare favorably to the MacBook pulling 286 minutes of web surfing.

    How big is the Sony battery, if I may ask? (Just for reference, take Voltage * mAhr to get Whr.) What sort of CPU, GPU, HDD, RAM does it use? What we need to see to prove it's possible is a Vista laptop with a 20W TDP CPU, 2GB RAM, 5400 RPM HDD, and 13.3" LED backlit LCD that can still get close to five hours of battery life with a 55 Whr battery. If you think you have one, get the manufacturer to send me one for review! :)
  • Spivonious - Thursday, October 23, 2008 - link

    Are you guys turning off the Vista indexer and SuperFetch? Those two things would run the harddrives pretty constantly on a fresh install, which would definitely drag down battery life.
  • JarredWalton - Thursday, October 23, 2008 - link

    Do normal users disable SuperFetch? I've disabled indexing as much as I know how, since I don't use it, but SuperFetch is part of Vista. Besides, it shouldn't run on battery power (and neither should indexing).
  • Spivonious - Friday, October 24, 2008 - link

    If you want to actually test Vista battery life, install the OS and use it for a week before testing the battery life. I agree with the other poster that both the indexer and SuperFetch are great features, but they do spin the harddrive when the computer is idle until the index is built and SuperFetch learns what you use most often.

    Spinning harddrive = lower battery life

    Comparing battery life between Vista and OS X is like comparing the time it takes to eat a pomegranate and an apple.
  • headbox - Saturday, October 25, 2008 - link

    no, battery tests let people know how long they can use their computer without plugging it in.

    You're not comprehending the article- the PC laptops are also being tested at idle, just sitting there doing nothing. If Vista is going to spend that entire time "superfetching" nothing, that's a problem.
  • jonmcc33 - Thursday, October 23, 2008 - link

    No, normal users do not disable SuperFetch. That's just bad tweaking advice, as much as turning Indexing off is as well. Both are amazing features added to Vista.

    I tested a Latitude D630 (2.6GHz Core 2 Duo Penryn, 2GB RAM) with Vista Business and a 9-cell 85WHr battery. Life was over 5 hours.
  • JarredWalton - Thursday, October 23, 2008 - link

    I wouldn't be surprised if there's just some glitch on many of the laptops that's keeping battery life down, but until some manufacturer can deliver Vista with 55 Whr and 5 hours (give or take) battery life I remain skeptical. Users shouldn't have to hack their laptop in any way to get the increased battery life; it should just work properly out of the box. You know, like the MacBooks with OS X.

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