Battery Life - Technically, No Better

Now it's time to talk about battery life. Let me run down the tests real quick. This is a combination of the tests Jarred runs in our standard notebook/netbook reviews and the tests I run in my Mac reviews. WiFi was always enabled and connected to an access point 20 feet away. The screen brightness was set to 100 nits and Windows 7 was configured to use its Power Saver battery profile.

The idle test is exactly what you think it is. The notebook just sits at the Windows 7 desktop with no screensaver active until it runs out of battery power. This is a good indication of the best battery life you'll get out of the notebook (e.g. just typing in a text document).

The light web browsing test comes from our Mac reviews and cycles through a series of web pages, pausing on each one for 20 seconds before going on to the next one. There are no flash ads on the web pages. This is the lightest load you'd see when browsing the web. A playlist of MP3s loops in the background.

The average web browsing test also comes from our Mac reviews and cycles through a series of web pages, pausing on each one for 20 seconds before going on to the next one. Each page has between 1 and 4 flash ads on it and there are three concurrent IE8 windows open, each doing the same thing. A playlist of MP3s loops in the background.

The heavy web browsing test opens four tabs in IE8, each heavily loaded with flash ads. The tabs stay open for a short period of time before the cache is cleared and the browser is closed. The system sits at the desktop for a short duration before launching IE8 once more and opening the same four tabs. The test repeats until the battery is drained. This should be close to the worst case battery life while browsing the web.

Our video playback test loops a 720p x264 movie in Media Player Classic Home Cinema x64 until the battery dies. The player uses any GPU acceleration present in the system.

Finally, the heavy downloading/multitasking test mixes a bunch of these tests together. The average web browsing test runs while a 480p XviD movie plays and while a download script executes and downloads files at a constant 500KB/s from a server.

I kept as many variables constant as possible between the two systems. Both are configured with the same amount of memory, with the same HDD and are set to the same brightness. Both systems are normalized to the same battery capacity to produce an apples-to-apples comparison of battery life.

And now, the results:

Battery Test Core 2 Duo P8700 (2.53GHz) Core i5-540M (2.53GHz) Arrandale Advantage
Idle 216 minutes 215 minutes None
Light Web Browsing 177 minutes 188 minutes +6%
Average Web Browsing 177 minutes 186 minutes +5%
Heavy Web Browsing 174 minutes 176 minutes None
Video Playback (x264) 132 minutes 134 minutes None
Heavy Downloading/Multitasking 144 minutes 147 minutes None

 

For the most part there's actually no improvement in battery life due to Arrandale. There are a couple of instances where we see a 5 or 6% increase in staying power but these two platforms are basically equal. That's great when you consider how much faster Arrandale is than its predecessor, but it's not great when you remember that we're talking about a fully power gated 32nm processor here.

If we look at our desktop Clarkdale results we see that idle power for Intel's 32nm part isn't very good. It's actually worse than the 45nm Lynnfield platform from earlier this year. Intel confirmed that there is a lot of optimization that has to happen with Arrandale. It looks like there are some silicon level tweaks that are on the roadmap to be implemented but we won't see them until the middle of 2010. That means while the first Arrandale notebooks won't offer any more battery life than their predecessors, the second wave of Arrandale should fix that.

There's also one more thing to worry about. All of our battery life tests are carefully constructed to make sure they execute the same amount of work on all systems. Twenty seconds takes the same amount of time regardless of how fast your CPU is. As we've already seen, Arrandale is nearly 20% faster than the current mobile Core 2 Duo at the same clock speed. It is possible for you to get much worse battery life out of Arrandale simply by doing a lot more work. Intel estimates that if we were to loop Cinebench over and over again we'd see about 30% worse battery life on Arrandale vs. the previous generation mobile Core 2. The reason being that Arrandale would be much faster, but draw more power. It would be doing more work over the course of the test.

For an end user all this means is that you can do things like encode videos faster on Arrandale than you could before. You can either do the same amount of encoding, faster, without hurting battery life, or you can do more encoding, in the same amount of time, while reducing battery life. Just something to be aware of as Arrandale notebooks have the ability to be just as power efficient as existing notebooks, but can easily be more power hungry if you let them.

Performance - A Huge Improvement Final Words
POST A COMMENT

38 Comments

View All Comments

  • Alberto - Monday, January 04, 2010 - link

    According to www.legitreviews.com/article/1169/15/ and www.legitreviews.com/article/1169/16/ the idle power is very interesting, lower then the older plataform of around 30%.
    Likely the difference between the two articles is due to a different bios. Moreover Legit has done a lot of tweaks to make the two plataforms comparable (cpu apart). In the battery test, the Monteniva laptop has a 6 cell battery instead of a 8 cell, but the 30% figure seem confirmated.
    Reply
  • HotFoot - Monday, January 04, 2010 - link

    One thing I've often wondered about battery tests is variability in the batteries themselves. Of course, over time batteries wear out and life goes down - but what about the difference between new batteries, even ones of the same rated capacities?

    I would be interested to see a review such as this one, but where the battery life is tested twice - swapping batteries between platforms and taking the average. Some adaptation will probably be needed. Or, maybe a standard battery testbench used for all battery life tests - which would involve adapters for each notebook.

    My point is uncertainty. I know it's not an academic paper, but if the variability in results is 10% or higher (which my gut tells me it very well may be with batteries), the conclusions drawn from the results could be radically different. Maybe it's not that bad, and a few tests into the subject would demonstrate that.
    Reply
  • JarredWalton - Monday, January 04, 2010 - link

    I had http://www.anandtech.com/mobile/showdoc.aspx?i=361...">two Gateway laptops that had the same battery design, only one was Intel-based and the other was AMD-based. After a request similar to yours, I swapped the batteries and retested. Variability was less than 2%, which is the same variability between test runs. Reply
  • kazuha vinland - Monday, January 04, 2010 - link

    Your unit was obviously just a prototype, but can we expect to see the first Arrendale laptops arriving this or next month? Reply
  • webmastir - Monday, January 04, 2010 - link

    love reading your reviews - very insightful. thanks. Reply
  • 8steve8 - Monday, January 04, 2010 - link

    when can we expect reviews of these ULV processors?

    when can we expect laptops with these ULV processors?
    Reply
  • strikeback03 - Monday, January 04, 2010 - link

    And seriously, wtf was intel thinking with these names? 5 processors, all at different speeds, with either 640 or 620 in the name. If a 620LM was the same speed as a 620UM but just used less power I could see it, but there are 3 processors with 620 in the name, running at 1.06, 2.0, and 2.66GHz. The consumer also has to know that a 620M is faster than a 640LM. Reply
  • ET - Monday, January 04, 2010 - link

    I'd love to see more comprehensive mobile benchmarks, but it looks like finally Intel graphics isn't the complete crap it used to be. Reply
  • yuhong - Monday, January 04, 2010 - link

    On Intel codenames, "Clarksfield" can be easily confused with the desktop "Clarkfield". Reply
  • yuhong - Monday, January 04, 2010 - link

    Oops, I mean Clarkdale by Clarkfield. Reply

Log in

Don't have an account? Sign up now