Battery Life

Testing battery life on a tablet is pretty grueling as these things are effectively smartphones with gigantic batteries. What would last for only a few hours on a smartphone can easily last over ten on a tablet. The iPad 2 is no exception.

As iFixit discovered, the iPad 2 features a nearly identical battery to the original iPad (25Wh vs. 24.8Wh). We already established that display brightness hasn't gone up so the only real impact on battery life will be because of the A5 SoC.


The iPad 2 WiFi's battery, courtesy iFixit

The ARM Cortex A9 tends to be more power efficient than its predecessor, the A8. With a shallower pipeline and the ability to execute instructions out of program order you get better performance per watt in most cases. As a result the A5 should complete bursts of instructions quicker than the A4 and get back to sleep sooner.

To put this to the test we put together a battery life test that combined our non-Flash smartphone web browsing test, checking for email every 15 minutes (via a Gmail account receiving ~100 emails per day) and constant local music playback while all of this is going on. The results are pretty much as expected:

General Usage - Web Browsing, Email & Music Playback

Over WiFi the Motorola Xoom and iPad 1 deliver very similar results. The iPad 2 pulls ahead by around 8%, it's not a huge advantage but it's there. Over 3G there's a noticeable drop in battery life, putting both of the iPad 2s below 10 hours and kicking the Xoom down to under 9 hours. All of the numbers on this chart are respectable however and you can expect a good day's worth of use out of any of these tablets.

Note that while the iPad 2 did better than its predecessor if you were to run an app that pegged both CPU cores at 100% you'd see reduced battery life on the iPad 2 vs. the iPad 1. Granted you'd also see better performance on the iPad 2.

Video playback is obviously an important function of these new tablets so we put together a H.264 decode playback test as well. For this test we transcoded a copy of Quantum of Solace from a 1080p BD source down to a 720p H.264 using Handbrake's Normal encode profile with one modification. In order to enable smooth playback on the Motorola Xoom we had to disable b-frames in the encode. The results are below:

Video Playback - H.264 720p Main Profile (No B-Frames)

The iPad 2 consistently lasted longer than the original iPad in our video playback test. The Xoom however did noticeably worse. Unfortunately only a portion of the H.264 decode pipeline is accelerated by NVIDIA's Tegra 2 in this test. When playing back anything more strenuous, portions of the pipeline are handled by the CPU cores in software. If you were to enable b-frames the Xoom would not only stutter but its battery life would drop to around 6 hours.

On the iPad 2 its Cortex A9s are mostly powered down during this test, on the Xoom the A9s are helping with the heavy lifting for video decode and as a result we see lower battery life. Kal-El is expected to address this issue head on.

The GPU: Apple's Gift to Game Developers HDMI Mirroring & Charging
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  • jalexoid - Saturday, March 19, 2011 - link

    The movie editing app on Honeycomb is there. And it's similar to iMovie.
    The Office look alike apps on iPad are still not good.

    Honeycomb struggles on the apps side, because the developer hardware was not there, when it was needed.
    But saying "So far only iOS has the most real apps" is a bit incorrect.
    Reply
  • WaltFrench - Sunday, March 20, 2011 - link

    “The movie editing app on Honeycomb is … similar to iMovie.”

    Yes, except for one thing: the YouTube of it shows it unable to show thumbnails properly and balky, rough animations. This wouldn't even get bronze at a beer-fueled coding contest.

    The two are exactly as similar as night and day: they live on the same planet.
    Reply
  • Zoomer - Saturday, March 19, 2011 - link

    >>Also, when you take it out in front of a client during a lunch meeting, it tends to impress them.

    That's probably why most buy it.
    Reply
  • Azethoth - Sunday, March 20, 2011 - link

    I bought my iPad to turn my daily NY Times habit at Starbucks paperless. So Wi-Fi only and one year = it paid for itself.

    Acting as an awesome controller for my home stereo setup is a total bonus. Same with reading books again via iBooks and Kindle.

    Yes, the underlying thing is I use it to consume and not to create. Unless you find an application that uses its strength in that regard it will just frustrate you as you try to do your pad-inappropriate netbook / laptop / PC / mini / mainframe or whatever apps on it.

    For me its a perfect way to avoid the netbooks / laptops which I have always loathed but get a little mobility. But then I only create on a desktop with 2560 x 1600 resolution so laptops will never cut it anyway.
    Reply
  • synaesthetic - Sunday, March 20, 2011 - link

    It's pretty refreshing to see someone who has actually found a usable niche for these things.

    It's just not too useful to a lot of folks. I carry my laptop to class already--yeah, this big, heavy MSI gaming laptop--because I need it. If I could carry something as light as the iPad and have it do what I need... I'd be sold.

    But it can't. And LCDs suck for long reading sessions. I'd rather have an ereader.
    Reply
  • doobydoo - Sunday, March 20, 2011 - link

    what is it you can't do on an ipad? Reply
  • LaughingTarget - Tuesday, April 19, 2011 - link

    Quite a bit, really. It's a lousy drafting platform. Don't try doing anything remotely related to engineering on it. Want to create a proprietary program to tie into your own business systems at work? Don't bother, you're not putting that thing on your iPad without Apple's permission. Don't bother trying to type anything lengthy up on the thing, you'll be operating, at best, on about 1/4 speed as a keyboard. It's a useless tool for accountants, field technicians needing to keep track of customer data, worthless for engineers trying to troubleshoot a power plant turbine on-site. Hell, it's even a horrible method of ringing up orders at a fast food joint.

    Go down the list of what people do for a living, the meat of the modern global economy, and you pretty much found everything the iPad can't do.
    Reply
  • kevith - Sunday, March 20, 2011 - link

    Use it as an E-reader?

    Well, only for books, that the the censors at Macintosh find good, clean and familyfriendly enough, that is.

    "When You start burning books, You will eventually end up burning people."

    That fact does not change over time...
    Reply
  • WaltFrench - Sunday, March 20, 2011 - link

    Let's be a bit more honest here: Heine was talking about government-sanctioned political violence, not commercial decisions. In fact, the considerations are almost exactly opposite.

    Commercial decisions have dozens of considerations, including authors' willingness to grant rights (e.g., Nabokov's Pale Butterfly not in any e-form), format (the wonderful Visualizing Information, also MIA) and a host of others. Freedom of speech implies the speaker's right to choose when and how he speaks; that means Apple's right to make commercial decisions about what it offers and what it does not.

    E.g., Apple no longer sells a camera, but they don't in any way restrict your ability to buy them or use them. Re books: if you like Kindle, for example, read them on the iPad. (As long as Amazon chooses to carry the work.) This is just like say, the B&N store across from my office: they don't carry titles they don't want, whether for expected lousy sales, or to keep the local Bigots United chapter from waving pitchforks at them. This freedom of Apple, which is NOT an arm of the US Government, to have its own voice, is just as important as preventing governments from banning speech.

    Maybe there is somebody at Apple who wants to treat you like a child. But about a hundred times more likely is that they simply want to do the stuff they think they do best, and some people act (childlishly!) as if Apple should run by different principles.

    PS: “Macintosh” is not the company you're talking about.
    Reply
  • vision33r - Saturday, March 19, 2011 - link

    The last thing you want is bring that $899 device in front of people and have app crashes and App drawer that doesn't work when you press it like a zillion times.

    People at work will just say you blow $899 on a netbook.

    Yes, the LCD on the Xoom is the typical 10.1" you found on Acer Netbook parts bin.

    How dare Motorola try to pass off a netbook for $899. How about the ASUS EEE Slate for $999 instead.
    Reply

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