Battery Life

With the iPad Air Apple moved to a 32.4Wh battery, a significant decrease from the 42.5Wh unit in the 3rd and 4th generation iPads. The smaller battery doesn’t come with a change to Apple’s claim of 10 hours of battery life, which implies a reduction in overall platform power. I confirmed a substantial reduction in platform power in my crude measurements earlier in the article. Although it’s possible for the iPad Air to draw substantially more power than the iPad 4, our earlier power data seems to imply that it’s unlikely given the same exact workload. Our battery life tests agree.

We'll start with our 2013 smartphone/tablet web browsing battery life test. As always all displays are calibrated to 200 nits. The workload itself is hidden from OEMs to avoid any intentional gaming, but I've described it at a high level here.

Web Browsing Battery Life (WiFi)

Our web browsing workload came in at exactly 10 hours of continuous usage - an improvement compared to the iPad 4. Battery life on LTE was good as well, consistently delivering just under 10 hours of usage. The fact that both LTE and WiFi tests deliver similar results tells me that we may be bottlenecked by some other component in the system (perhaps display?).

I've been running the same video playback test for a while now, although we're quickly approaching a point where I'll need to move to a higher bitrate 1080p test. Here I'm playing a 4Mbps H.264 High Profile 720p rip I made of the Harry Potter 8 Blu-ray. The full movie plays through and is looped until the battery dies. Once again, the displays are calibrated to 200 nits:

Video Playback Battery Life (720p, 4Mbps HP H.264)

Video playback battery life also improves slightly compared to the iPad 4. Apple’s battery life claims aren’t usually based around video playback, so exceeding their 10 hour suggestion here shouldn’t come as a shock. Apple’s video decode power has always been extremely low.

Our final cross-platform battery life test is based on Kishonti's Egypt HD test. Here we have a loop of the Egypt HD benchmark, capped to 30 fps, running on all of the devices with their screens calibrated to 200 nits.

3D Battery Life - GLBenchmark 2.5.1

Our 3D battery life rundown test shows a substantial improvement in battery life over the iPad 4. IMG’s PowerVR G6430, running a moderate workload, can do so more efficiently than any of the previous generation GPUs in Apple’s SoCs. Much like the A7’s CPU cores however, there’s a wider dynamic range of power consumption with the G6430. Running at max performance I would expect to see greater GPU power consumption. The question then becomes what’s more likely? Since the majority of iOS games don’t target the A7 (and instead shoot for lower end hardware), I would expect you to see better battery life even while gaming on the iPad Air vs the iPad 3/4.

Charge Time

The iPad Air comes with the same 12W USB charger and Lightning cable that we first saw with the iPad 4. Having to only charge a 32.5W battery means that charge times are lower compared to the iPad 3 and 4:

Charge Time in Hours

A full charge takes a little over 4 hours to complete. The adapter delivers as much as 12W to the iPad, drawing a maximum of 13.5W at the wall. I still think the sweet spot is somewhere closer to 2.5 hours but that’s another balancing game that must be played between charge time and maintaining battery health. It’s still so much better than the ~6 hours of charge time for the iPad 3 and 5.69 hours for the iPad 4.

WiFi & LTE Connectivity Usability, iOS 7 and the Impact of 64-bit Applications
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  • Krysto - Friday, November 1, 2013 - link

    Why would the aspect ratio matter in calculating the surface area? Reply
  • thunng8 - Friday, November 1, 2013 - link

    Of course aspect ratio affects area

    Take an extreme example a tablet of length 25cm and width of 1cm. Surface area is 25cm^2. Diagonal is still 25cm. ( to be more precise 25.02cm).
    Reply
  • gnx - Thursday, October 31, 2013 - link

    As I mentioned, I find both a 7.9 inch ipad mini and galaxy note 8.0 (which is really closer to iPad Mini) both too cramped and small, as I use the table for foremost as a document reader on the go. And just to add, the Galaxy Tab 8.9 was 1280:800, thus 16:10, making even overall space closer to an iPad.

    Finally, for practically reasons, the Galaxy Tab 8.9 was nice, since because it's height in portrait mode was almost identical to an iPad 2/3/4, just narrower in breath, I could chose from most iPad accessories such as any carrying cases, pouches, bluetooth keyboard, etc.
    Reply
  • yoshi1080 - Thursday, October 31, 2013 - link

    I still love my iPad 3, but I'm thinking about upgrading. I do a lot of stuff on it and sometimes I wish it'd be faster. The iPad Air should be around 3–4x faster, right?

    Two of the most demanding tasks where I wish my iPad was faster are photo and video editing. I've already read that iMovie is supposed to be really fast on the iPad Air, so that's a clear advantage. My iPad's speed is sufficient for JPEG editing, but RAW processing (with PiRAWnha) is practically unusable. Processing RAW photos on my iPad would be my dream because photo editing on it is just so much more fun than on my iMac with the dreadfully slow Aperture – I'd be happy with getting 90% of the quality, but RAW is mandatory for me.

    Up until now I thought the iPad Air would be much better suited for PiRAWnha. But now Anand writes about the RAM bottleneck due to the 64bit architecture and this makes me wonder: On the original iPad, the app often complained about too little available RAM and eventually crashed. I feel like the 1GB RAM on the iPad 3 is the reasonable minimum – would the Air be a disappointment in that regard? On the other hand, Adobe is working on bringing Lightroom and those smart DNGs to the iPad, and the beta version has even been shown running on an old iPad 2.
    Reply
  • darkcrayon - Thursday, October 31, 2013 - link

    Apps just don't need as much RAM as we think they do, especially mobile versions. Sometimes I'm surprised what can still run just fine on an iPad 2 (also helps of course that only one foreground app needs to run at a time). The Air should be 4 times faster than the iPad 3- should be no contest, especially in CPU. Reply
  • Death666Angel - Thursday, October 31, 2013 - link

    Well, using one app at a time is fine, but browsing the web with a few tabs open and then switching to one or two other apps gets Apple device quickly ejecting stuff from RAM, where my Nexus devices are still having the pages loaded. :) Reply
  • fteoath64 - Thursday, October 31, 2013 - link

    Thanks for the detailed review!. As I suspected the A7 behavior would have been rather different to wring out more performance out for the iPad as compared to the iphone. As you stated in the power consumption measurements, it seems the A7 is rather power hungry and only aggressive power management gets the battery life it needs. I am sure, it would be waiting for the TSMC 20nm process node as it seems this chip is just at the brink of 28nm as it is today. In making, the battery last so long without negatively impacting user performance, Apple has done a great job to achieve the balance using software. From the power draw alone, I figured out why it was clocked at such speeds instead of 1.6Ghz or 1.8Ghz. It cannot afford the power budget associated with it!. Reply
  • iwod - Thursday, October 31, 2013 - link

    Sk Hynix Just announced a 6Gb LPDDR3. A Maximum of 3GB when 4 of them Stacked, Interesting isn't it?
    How about 2 Channel use? 1.5GB of Memory? May be a big company / customer would like / require this ?
    While I hope Apple will give us 2GB in next generation. The reality may very well be we get 1.5GB of memory only.
    Reply
  • bigup - Thursday, October 31, 2013 - link

    is the 1GB RAM really a deal breaker? sold my ipad 3 to buy the iPad Air but now having seconds thoughts - what do you think? Reply
  • darkcrayon - Thursday, October 31, 2013 - link

    It's not a deal breaker. You could argue in 2 years it would be better with more, but you're already the type of person that sells their less than 2 year old iPad for the latest, so... ;) Reply

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