Battery Life

With the move from featurephones to smartphones, battery life has been and continues to be a critical issue. While it wasn’t unusual to see a week or more of battery life on a featurephone, some of the earliest smartphones couldn’t even last a day. While tablets seem to have a much easier time achieving high levels of battery life by virtue of massively increased volume, they still face similar issues as they are often used for gaming or other more intensive workloads that a smartphone is unlikely to see nearly as often. In order to test this, we run our tablets through a standard suite of tests of various use cases. In all cases where the display is on, all displays are calibrated to a brightness of 200 nits to draw useful relative comparisons.

Web Browsing Battery Life (WiFi)

In our first test, we see that the iPad Air 2 is about roughly equivalent to the original iPad Air for WiFi web browsing. This is actually a bit surprising as the battery in the iPad Air 2 is approximately 84% of the iPad Air. This would mean that we would expect the iPad Air 2 to get around 8.4 hours of battery life in this test, which represents a 16% gain to efficiency. It’s likely that these improvements to battery life come from the new process node on the A8X, along with the newer WiFi module.

Web Browsing Battery Life (4G LTE)

Along the same lines, the LTE web browsing test tracks quite closely but it seems that there’s a minor decrease in efficiency gains when compared to WiFi. This difference is likely to be explained by the much higher bandwidth available in WiFi when compared to LTE.

While the web browsing tests are effective at ensuring faster SoCs aren’t punished, this inherently tilts battery life towards a more display-bound mode rather than compute-bound. Unfortunately short of a jailbreak it doesn’t seem possible to get an effective Basemark OS II battery test, so we’re mostly limited to a test of GFXBench’s unlimited rundown.

GFXBench 3.0 Battery Life

GFXBench 3.0 Performance Degradation

As one can see, the iPad Air 2 is one of the best performers on this test, considering its frame rate and runtime. While NVIDIA's GK20A GPU in Tegra K1 can get close to the GX6650 for short periods of time, over a long workload it's pretty clear that the GX6650 on 20nm has better sustained performance and significantly superior efficiency as it doesn't throttle until the 200th iteration of the test. It's important to note that the iPad Air 2 is running at a higher native resolution here, so relative to SHIELD Tablet a scaling factor needs to be estimated in order to get an idea for performance at the same resolution. During this test I saw that the skin temperatures never exceeded 45C, so this isn't the result of Apple choosing to run the device hotter than most.

Charge Time

While tablets deliver some great battery life in general, charge time tends to be much slower than that of smartphones as the battery is much larger and charging the device isn't as time critical due to the longer battery life . While we can't quite cover the full range of battery life uses cases, it's important to remember that in cases where the platform is otherwise identical beyond display that battery life scales linearly with overall capacity. In order to test charge time, we measure the time it takes for the battery to reach 100% from a fully-depleted state.

Charge Time

As one can see, the smaller battery seems to have a noticeable impact on charge time, although the difference isn't really all that notable as the difference is only around ten minutes at the end of the day.

GPU and NAND Performance Software: iOS 8
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  • robinthakur - Monday, November 10, 2014 - link

    Lol, you hit the nail on the head there. You can't even install OTA updates on rooted Android devices with custom recoveries without restoring the stock one and most banking apps don't work on them either. To do either you need a PC opr a mac and you need to use the command line. How user friendly is that?

    The last time I took off the custom recovery and put stock back onto my HTC One M8 and then tried to update, it wiped all the data off of the phone. After that, I bought an iPhone 6 Plus and am much happier and more secure in the knowledge that my phone backs up automatically overnight (every night) to iCloud. Having used iPhones since 2007, iTunes hasn't been required for mnost things since the iPhone 4 launched in 2010
  • craighamilton - Saturday, December 6, 2014 - link

    Truly amazing, one of the high rated tablet. You should take a close look at the guide at
  • NEDM64 - Saturday, November 8, 2014 - link

    Exactly, if you are like in tens of thousands in a pool of hundreds of millions, over the history of 7 years, you may get that...

    That's the problem, you get updates on iOS, while on Android... unless you buy the "right device" you may have something like 18 months of updates.

    And what's the problem with iTunes then? I've it running on my Windows box, and for the monster of multipurpose App it is, it consumes next to nothing of RAM.

    At least is a easy to use and stable program...

    Contrary to the Nexus "fastboot" command line tools...

    And most of software that Android vendors make you install, like Samsung KIES, that's great software, isn't it?
  • carloshehe - Sunday, November 9, 2014 - link

    OS updates aren't too necessary on Android. You can still run all the latest apps. U like iOS, apps have no OS version requirements.
  • akdj - Monday, November 10, 2014 - link

    I'm not sure I've read such a backward comment in my life.
    As an owner of bit iOS and Android devices (latest hard/software), your experience is undoubtedly 180° different than mine
    My nine year old is still enjoying the iPad 2, even with the current version of iOS he's enjoying ten to twelve hours of better life
    Same can't be said for the 'Xoom' ...or the nexus 7 ('12) ...I'm not sure when I pulled out the 2013 ?Nexus 7
    That said, when it comes to 'tablet apps' and 'choice' the Hundreds of THOUSANDS ...the Android tablet experience is an absolute, utter and catastrophic Joke!
    I love my Note3. Looking forward to possibly updating to a Note 4 --- but four years of getting butnt by the tablet development community and its lack of interest in 'developing' for the Android tablet community, I'm done
    Though a bit curious. iPad Air 2 drops (have one btw and its everything the reviews cracked it up to be, plus! -- & I'm coming from the original Air, my wife the iPad 4 she didn't want to give up. Case thing). And so does the price of the new Nexus 9?
    Why? Wasn't it a 50% drop? Maybe I dreamt it....not sure, and not knocking the Nex9. That said, there's only so much you can do with the UI of your springboard. At some point its time to use your tablet to do something
    When that time comes, you'll be glad you chose iOS, regardless of your interest, hobbies, media you enjoy to play, media to manipulste or create. Music, video/still and artistic creation on the iPad ...its apps and its options are second to none ...
    Thanks for the write up.
    What a slab
  • Michael Bay - Tuesday, November 11, 2014 - link

    Your shilling is beyond pathetic.
  • noelbonner - Tuesday, November 11, 2014 - link

    There are way better phones according to CONSUMER BASED rankings, just see
  • valnar - Sunday, November 16, 2014 - link

    I reject the very foundation of that article. Treating a phone like a computer misses the point. It is absolutely NOT important to pick a phone based on the resolution, camera or power. Battery...ok yes.

    What's more important are the apps it runs, how easy is the UI, stability, speaker & mic quality, etc. The things that matter in a smart phone. The ±10% speed or rez differences in various phones is irrelevant.
  • akdj - Thursday, November 27, 2014 - link

    Huh. Amazing that year in, year out they contine breaking sales records from the previous launch customer satisfaction has remained in slot #1 for damn near every quarter since 2007 and as far as 'better' phones, even the connotation being subjective ....ultimately and objectively there isn't a "better phone". Just different now
    2007/08 and the introduction of the SDK & the App Store completely changed a massive, easily one of the top five, maybe three 'growing' areas of our world today. Wireless comms first for voice first (remember 'Can you hear me now?' And the days of Nextel, Blackberry corporate dominance and shitty analog coverage?)
    ...we've moved into 'texting' in a signficantly easier way than the Nokia flip phone with 12, standard 'phone' buttons and their associated three letters. Apple introduced in '07 a game changing, corporate smashing product that continues to better iteseld with each iteration. I've owned em each and because of how our company is run...we also provide employees with iPhones/iPads while I carry both. 6+ and Note 4. They've voth got their places and the sizes of their displays is a life saver to this mid 40s guy
    I can't see anything anymore when it comes to reading. Cheaters or Else...
    (Wal mart reading glasses;))
    BUT, today's HiDPI dispays at 5-6" in these svelte profiles and 'weight' (lack of) with their Power, speed, efficiency and reliability --- ultimately make it 'that time' in history.
    Telecommunications changed the world early in the 20th century. An extension of Moorse code. Voice to voice. Operators and analog switch boards and Mama Bells reign/monopoly on America's 'booming' new technology. All analog. All switched on site. Patch cords that my grandmother ran for almost forty years and plenty of advancements ...all the way until 'digital" phone lines were installed and the history of the 'switcher' is just that. History

    Which two birds one stone BS, valnar underneath is tells is the 'very foundation of (sic) article....'
    And I quote, "Treating a phone like a computer MISSES the point". They're VERY MUCH a computer, that fits in your pocket and performs much faster than computer we were building and drafting, coding and editing, emailing and surfing, playing games and 'communicating' with not JUST voice but video, text 'artistic creation!'
    To dismiss a smartphone as inferior to a computer in ANY way shows a significant generational gap
    When your mobike, wireless provider allows for the speeds of LTE (I'm routinely between 35/40Mb/s down and 40150 UP!
    That's ubelievable when I think back to my IIe, Ultima I, II, III ...Booting to the promot 'BRUN ..xxxxx'
    To 33!& 54 baud modems, the handshake noise like yesterday and was floored with the performance of SSD va HDD. Bluetooth's progression and the idea of an IPU, MPU....gyros and accelerometers ...if you'd sit back five minutes and think about their sheer 'abilities', other than 'Us, and these that frequent Anand's site ...and enjoy technology, the mass population is easily taken care of with 95-98% of all comouter tasking they were doing in 2010 on 110/220 (plugged in) ...
    ...Today being done on a gram measured in grams, a few hundred at that and fit in your pocket. They're reliable. They aggregate, integrate and oranizate;) everything about my life and 27 year business
    As a pilot I can't begin to describe the differences between gettin my pilots license in 1987 and today. From GPS to LTE, TCAS to ADSB ...planning my trip and checking real time weather, calculating fuel and picking my diversions if needed. Jep charts n plates and app/dep up to the minute changes to your approach or arrival ...hell, even with an app, Flight 24 I bekeive...if you've got it you can follow a loved one all the way through to landing and gate release. Leave your house with perfect timing lol
    Honestly, there just AREN'T 'way better phones'. Apple, HTC, LG, & of course samsung have helped each other
    For me, I wouldn't be caught without both. I want to know the differences, what going to help me and be the most compelling reason to choose that platform, OS or Eco system
    They ARE computers. Possibly you didn't ride DOS, the intro to 8086 and 8/16/32/64 bit programming and hardware but the amazing Moore's law has taken over. I, for one, couldn't. E happier.
  • akdj - Thursday, November 27, 2014 - link

    "And I quote, "Treating a phone like a computer MISSES the point". They're VERY MUCH a computer, that fits in your pocket and performs much faster than ThE computer(s) we were building with and drafting (the initial CAD, paint,motion and still editing), coding and emailing surfing or producing a song, video (or both) in Los Angeles at a studio or your home swimming pool , playing games and 'communicating' with not JUST voice but video, text 'artistic creation' and SOOO much easier than a 'computer' in SO many cases, situations and emergencies and for the vast majority of our population today than yesterday
    IF ALL you need is a phone, I'm with you. There's a better flip phone with those dozen digits, # & * as well as the 'green' & 'red' buttons on top and middle 'select'
    If you're going to use your phone for more than calls, indeed, you'll find your iPhone,mS5 G3 or the latest Lumia to be a HELLUVA lot closer to a comouter than you're implying.
    That said, if this is an extremely rare circumstance and you're working opposite me with my 4k conversions and encoding, I concur;)
    There afain though ...our last two docs have used footage from iPhones and Androids (not a WinPhone yet unfortunately ...but I'm one of nine peeps that I think enjoy Win8.1. I'm OS X based and only own two Windows machines now...but I digress, my point was even my iPhone works perefectly on Win 8.1 does iTunes! I'm pretty floored how quick it (now is, I left to OS X personally and with the business after a really bad crash in Vista in 2007---& hadn't looked back until earlier this year when I needed a Win rig. Bought an HP 2/1 slab or attachable and all aluminum body core i5. It's pretty cool having CS6 suite on a (albeit extremely large and unwieldy) tablet ...
    I am rooting for all of them. That said, Mt View and Cupertino have vertical and horizontal aggregation and integration. Google doesn't. The former two's run deep and have history, trust ... Obviously fans with zest but IF a phone isn't s computer, Android/Google better spens some serious time on Chrome;)

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