Battery Life & Power Analysis

The final unknown in all of this is power consumption. ARM's Cortex A15 isn't really supposed to be a sipper of power, and when placed in a notebook I don't know that there's a lot we can conclude about how it stacks up to Atom either. Some high level power consumption data would normally help but these two platforms are fairly different:

Samsung Chromebook Power Consumption Comparison
Display @ 200 nits Idle Kraken (Avg) Kraken (Peak)
Samsung Chromebook 500 (Atom N570) 11.53W 14.4W 15.2W
Samsung Chromebook 303 (Exynos 5 Dual) 6.33W 10.5W 11.3W

The new Chromebook consumes considerably less power at idle than its predecessor. The smaller display, simplified motherboard and truly integrated SoC platform are likely all to thank for this. The significant reduction in power also helps explain the big reduction in battery capacity as well.

Under load, the two platforms do see differing levels of additional power consumption. The new Exynos 5 based Chromebook sees a dramatic increase in power consumption under load, hitting 10.5W (a 66% increase over idle) while running Mozilla's Kraken benchmark. The Atom N570 based Chromebook increases power consumption as well, but just not by as significant a degree: ~25%. This actually helps illustrate exactly why Atom wasn't phone worthy in its earlier incarnations. Contrary to popular belief, it wasn't actually peak power consumption that was the problem (a move to 32nm can easily eat into these numbers). The total platform power consumption, particularly at idle, was Atom's real problem in the early days. It also turns out that this is much of what keeps Intel's Core processors from moving into ultra mobile form factors, something that Haswell is supposed to address.

Given that we're dealing with somewhat different panels here, I wanted to see what power consumption looked like if we removed the panels from the equations. I re-ran all of the power data with the display turned off:

Samsung Chromebook Power Consumption Comparison
Display Off Idle Kraken (Avg) Kraken (Peak)
Samsung Chromebook 500 (Atom N570) 8.82W 11.4W 12.4W
Samsung Chromebook 303 (Exynos 5 Dual) 4.07W 8.32W 9.27W

The old Atom based Chromebook uses more than twice the idle power of the new version - it's no wonder Google was able to get away with a battery half the size. Once again however we see a much larger increase in power consumption once the Cortex A15 is under heavy load. Active power consumption more than doubles on the new Chromebook, while we see around a 30% increase on the Atom based system. I do wonder what will have to be done to get the Exynos 5 Dual into a smartphone as an increase of ~4W under load just won't cut it in a phone. The Atom platform shows a 2.6W increase in power under load, which sounds about right for a high clocked 45nm part.

Web Browsing Battery Life

Despite the more power efficient platform, the reduction in battery capacity puts the new Chromebook well below the Atom model in battery life. Our wireless web browsing test put the new Chromebook at just over 6 hours of continuous use on a single charge. For a notebook that's not too bad, but compared to modern tablets it's not good.

The performance gains over Atom (and by extension, the ARM Cortex A9) do give us some indication as to what could be done to get Exynos 5 into a smartphone. By dropping clocks much lower than 1.7GHz Samsung would be able to maintain a performance advantage in a very power constrained device and hopefully keep power in check. The photo above features a list of all of the voltage levels supported by Samsung's Exynos 5 Dual as implemented in the new Chromebook.

Performance: Atom vs. ARM's Cortex A15 Final Words
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  • actionjksn - Thursday, November 08, 2012 - link

    How would the performance on this compare to a similarly clocked Core 2 Duo? I'm talking about CPU tasks not graphics. Reply
  • TheJian - Monday, November 12, 2012 - link

    You're forgetting to mention your basing that on a 1.3Ghz cpu from a year ago instead of the 1.7ghz tegra3+ that they're currently putting out (htc one x+ etc). That's about another ~27% you're leaving off NV's table right anand?

    So Intel's current tech is just about to catch NV's old tech with Tegra4 just around the block that will increase cpu (I don't expect much here, but they don't need much already quad and performs on par with what just came out to a large degree), and double gpu since going quad instead of dual, so at worst it will double if no chip improvement at all, and dual channel finally. Looks like they'll be behind again just after launch I guess? They'll have to do better than catching last years tech. And they didn't make it into xmas devices like Tegra. So again NV will get their tech out in time in Q1 for craploads of devices to be planned all year. I'm thinking it's best to be fastest in March/April if you want to be designed into Xmas devices.

    Surface may have chosen the 1.3ghz but they should have ran a 1.7ghz Tegra3+. I guess it saved them $10/surface (less?). I'm sure customers would rather pay $5-10 for another 30% performance. They should at least offer the option. Oh well. I told my dad to buy a Nexus 10 for xmas anyway and I'll wait for a great 10in Tegra4 as if I'm going to game (dad isn't much) I want Tegra game optimizations and everything out now isn't quite as good as I'd like for Xbox360 portable replacement and double as a laptop i9300 replacement (it's 8yrs old...LOL). Nvidia seems to be the only one helping devs make some great stuff and gaining praise from the likes of Carmack and Epic's Unreal team.
    Tegrazone.com has some great games in the pipe. I'm looking forward to Baldurs Gate enhanced on a 65in TV in the near future too...LOL. That game should run on anything out by everyone on the top end and give gamers a good 100+hrs of fun on the bigscreen without an xbox360/ps3. With my limited game time, it should hold me over until android gaming really takes off. There are 5 unreal 3 engine games in the pipe now, and lots of other good looking stuff at tegrazone says next xmas should be excellent. I'm sure Id's engine will get used by them in a few games also. Between these and my PC I should have no reason to even look at an xbox720/ps4. I'm guessing a lot will be in the same boat.

    I may have to pony up for the cube u30gt jelly bean to get me to xmas which should produce a tegra4+. Then again going from 40nm to 20nm there may be no need. That's a HUGE decrease in chip size and samsung is better than TSMC at any process. The U30GT (and it's ilk) look pretty dang good for $200 tablet at 10in for something to use for training vids/books etc until next year.
    Reply
  • sathish2020 - Wednesday, November 21, 2012 - link

    "With Apple pushing at the top and Google working the bottom" Nice one. Reply
  • deslock - Thursday, November 29, 2012 - link

    Thanks for the detailed (as usual) review. A question:

    Since it idles at 6.33W and has a 30 Watt-hour battery, shouldn't it last less than 5 hours with the screen on? It lasted 6.07 hours in the browsing test.
    Reply
  • ramonchis - Thursday, January 10, 2013 - link

    Hi. I got one of these a couple of days ago. In the first day I broke the LCD by putting some weight on the laptop.

    I went to the store (Best Buy) to check if they could repair it of exchange it, but they did not offer any solutions.

    So.... I would like to change the screen myself, which I have done in the past with other laptops.

    Did you get a chance to open the screen lid? Do you know the LCD model?

    Thanks!
    Reply
  • calden - Sunday, January 27, 2013 - link

    I have used the Chromebook Since the CR-48 then moved to the Acer and now this one. You will be surprised as to how useful the apps found in the Google store really are. I use Microsofts 365 and I am just as productive as if I was using the full program on a normal laptop. I recently found a new online service called Lime Documents, fantastic. The writing program is called Lime Writer and after using it I can honestly say I will never have any use for none web apps again. www.live-documents.com/live_writer.html The same goes for the Excel and Powerpoint clone, there awesome apps.

    I love having the security the Chromebooks give me, I travel a lot and have either have had my laptop stolen or lost after a night of drinking. These give me the freedom of just shrugging my shoulders and saying oops instead of freaking out that someone now has photos of me and my dog with peanut butter. That was a joke of course it was the cat, at 250 dollars though these really are disposable computers.

    My company recently bought over 300 Chromeboxes and Chromebooks. Our company is an all Unix environment with 90 percent of our data and internal apps being served from Oracle, in which all info is displayed with web apps. The few people who need Office or other software like the treasury department can display them using Citrix. A feature that was left out of the article, I for one use a CRM program called Goldmine. When I travel the 4G connection I have is more then fast enough to display this program and others. The Chromeboxes make a perfect dumb terminal, their also priced much better then the HP solution we were using. Google also doesn't mess about, we have many spares to switch out the defective ones if nessecsary. We then send them back to Google who just gives us new ones.

    To tell you how useful a web program can be our software development team uses online development apps that were found in the Google store. They claim it's as good as if they were using Eclipse or Netbeans. I was actually amazed when they showed me. It's also a good employee incentive to give out a laptop to everyone even the secretaries. Yes they are just Chromebooks but our staff really seems to enjoy them as they can't muck'em up like they can with ordinary machines. We supply our people with Samsung 550's, the ARM version was deemed to slow but I took ome of the evaluation machines for my self as I like the size. I find it to be quick enough for my needs, I can stream 1080p movies from my Google Drive account without breaking a sweat so it's just fine for my needs.
    Reply
  • qwerty321 - Wednesday, March 20, 2013 - link

    One of the guys working at Linaro claims he has the USB 3.0 port pushing 70+ MB/s. I'm guessing an engineer knows better than a laypress hack. Reply
  • EvilTed - Saturday, September 07, 2013 - link

    He should enlighten everyone how?
    I call BS on your enlightened engineers claims!

    I'm fuming mad at Samsung for blatant false advertising.
    I have tried ChromeOS as well as Ubuntu with Unity and XFCE and the average throughput over USB 3.0 is 16MB/s, which is slower than my 2011 Mackbook Pro over USB 2.0 :(

    I actually bought my Chromebook for image transfer and storage from SD card to USB 3 drive.
    The fact it cannot produce at all has left me with a $250 doorstop.

    Class action suit anyone?

    ET
    Reply

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