The Apple iPad 2 Review
by Brian Klug, Anand Lal Shimpi & Vivek Gowri on March 19, 2011 8:01 PM ESTBattery 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:
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:
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.
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shangshang - Sunday, March 20, 2011 - link
but if you enough fanatic hipsters, +1 device can become a primary fashion must-have.And it's not just yuppies. There are so many geeky engineers at my work place that have an iPad so they can just put it next to there desktop PCs. Worst, there are some managers who use an iPad right along side their laptops in meetings. Baffling to me. I can only chuck it down as fashionable. I mean it's the same reason women pay $2000 for an LV purse that most men would deem god ugly.
kasplat99 - Sunday, March 20, 2011 - link
Last fall there was a discussion of a limitation of 16GB on photos in the iPad.http://discussions.apple.com/thread.jspa?messageID...
I haven't been able to find out whether this was resolved with an iOS 4.x update or the problem persists. This probably is not a limitation of the camera connector kit itself, but rather the photos app, either for total number or data size of photos, but regardless it is a serious limitation if trying to use the iPad for photo work or backup on a long trip.
Testing should be done on 32GB or 64GB iPad if anyone wants to check on this.
BlendMe - Sunday, March 20, 2011 - link
While reading the section on the cameras and the camera UI, I was wondering if you couldn't have saved yourself 1/2 page of writing by just switching on rotation lock? I see that the rotating controls are annoying, but isn't that what the rotation lock switch is for? To keep the UI from rotating?dagamer34 - Sunday, March 20, 2011 - link
That's a pretty bad hack for a problem they should have realized themselves if they ever tried to take a picture with the iPad 2.BlendMe - Sunday, March 20, 2011 - link
How is that a hack? That's what the switch is for (unless you set it to be a mute switch). If you use it to lock the rotation in a browser it's considered a feature.Theoretically (I don't have an iPad 2 and won't be able to try one for at least a week) this switch should allow you to place the capture button on any side of the screen.
I'm kinda surprised Anand/Brian/Vivek didn't even mention it, given that most of their reviews are very thorough and in-depth.
Azethoth - Monday, March 21, 2011 - link
I second that notion. My default is to have rotation locked. I loves me some landscape mode and when reading with it flat it freaks out without some rotation discipline.Now that its on the external switch again there really is not much issue.
Still, it was a major UI oversight. I think they got "lucky" that Jobs was sick and didn't see that rubbish and chew someone a new one. Heck, even Gates would have noticed such UI incompetence.
Bosh - Sunday, March 20, 2011 - link
Yes, you can wait and wait and wait and...........WaltFrench - Sunday, March 20, 2011 - link
Aw, cut @geekfool a break: he's waiting because by then, Flash 10.3.0173 will actually have watchable 720 framerates on a quad-core Tegra.There's geek and there's geek. Perhaps geekfool has drunk the Adobe jizz bigtime. With that list of priorities, he's absolutely doing the right thing.
LauRoman - Sunday, March 20, 2011 - link
Great review but it doesn't hold a candle to Charlie Brooker's 3 and a half minute insightful dissection of the differences between the two devices.http://www.youtube.com/watch?v=qNSn6AtdSGM
kube - Sunday, March 20, 2011 - link
Great review.I have an iPad 1 and plan on upgrading.
The review says that the principal use is email and web-browsing. Like most my use focuses on a few uses. But the most important is reading.
1. books. I use the Kindle app most, but sometimes ibooks. I share lots of books with my daughter, who uses a kindle device. Ebooks have probably doubled my book reading.
2. journal articles. For me, this is revolutionary. I'm a scientist, and over the past decade journal articles have migrated from print to pdf. With applications like "good reader" and especially "papers", my reading experience has changed. Reading a journal article pdf off of a computer screen is a second-rate experience. Reading off of the ipad, for me, is as good or better than reading print. As pdf applications have matured, the ability to high-light or write notes on the pdfs has gotten better. Really terrific.
3. Other pdfs. Viewing pdfs of slide presentations or theses or other stuff is great.
4. Instapaper. Can't believe its legal. While saving standard web pages is nice, it really shines at saving things like extended magazine articles. Things like the NY Times book review or NY Review of books articles. Extremely comfortable reading experiences, and easy to share with friends via email.
Another comment. My college-student daughter has an 11-inch macbook air. Its her only computer and is a terrific device. it seems to be a better device for students. It overlaps the function of the iPad making it hard to justify both.