Battery Life

When Apple unveiled the iPad, they promised that it would achieve 10 hour battery life. That has been something of a standard for tablets now, and for the most part we've seen that high end tablets end up meeting that goal, while mid range ones often end up falling short of it. 2015 was a bit of an exception to this in some ways, with many high end tablets also missing this goal by several hours in some cases. Due to the nature of tablets and how they're used, it's really difficult to recommend one if it doesn't achieve enough battery life to last you through the day with a normal workload.

To test the Pixel C's battery life I've attempted to run it through all of our battery tests. First up is our internal web browser test, followed by our video playback battery test.

Web Browsing Battery Life (WiFi)

It's clear that Google's use of a LTPS display and a large battery pay off big time when you look at battery life. Even with the SoC staying on its higher-power A57 cores, the Pixel C manages to last for over 13 hours in our web browsing test. This puts it ahead of every other tablet on record, and by a large margin too.

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

In video playback the Pixel C once again comes out on top. This is quite surprising, as normally AMOLED tablets perform best in this test due to their ability to turn off pixels when displaying black, as well as their general efficiencies with darker colors and shades. The gap between the Pixel C and the Tab S2 isn't insignificant either, so Google should be very happy with what they've achieved here.

BaseMark OS II Battery Life

In BaseMark OS II's CPU-bound battery test we again see the Pixel C top the charts. This is really surprising to me, because on the SoC side we're looking at four Cortex A57 cores on a 20nm process. Again, Google's large battery and LTPS display help a great deal, but it's also clear that Tegra X1 isn't causing any significant problems for the Pixel C as far as power consumption goes.

At this point I would normally continue to run our PCMark and GFXBench battery tests. Unfortunately, the Pixel C's software makes it incapable of completing either of them. I made five attempts to complete PCMark, which took a great deal of time as the test runs over many hours. In all cases the tablet locked up during the test and required a hard reboot. It may be possible to eventually get it to complete, but I didn't feel that it was worth delaying the review further in the hopes that I could eventually get the Pixel C to complete the test properly.

As for GFXBench, it instantly stops due to it detecting that the tablet is plugged in. I believe this may relate to Google's system for inductive keyboard charging, but whatever the cause may be the result is that I can't get a battery result for GPU-bound workloads either. It's worth noting that the web test also required several runs before I could get it to complete the test without the tablet crashing, so that's something to think about as far as software stability and reliability goes.

In the end, what I have seen of the Pixel C's battery life leads me to believe that it's quite good, but we're definitely not looking at the entire picture here due to the missing data. I can say that in my experience it seemed to last a long time, so if I had to go out on a limb I would say that the combination of the low power LTPS display panel and a relatively large battery allow for very good battery life even with the CPU running on its A57 cores. Since Tegra X1 has a great deal of GPU power I really wish I could have gotten a GFXBench battery result, but there's not much that can be done there.

Charging

Since tablets usually offer enough battery life to get through the day, being able to charge them incredibly quickly becomes less of a need than with smartphones because you'll often end up only charging your tablet overnight. That being said, the immense charge time required by older tablets which required larger batteries to power their SoCs and displays meant that if your tablet battery did die you probably weren't going to get to use it until the next day. With modern tablets we've seen a push to reduce battery capacity, as well as the inclusion of 10-15W chargers to reduce charge times.

Charge Time

The Pixel C ships with a 15W charger with a USB Type-C connector. The cable is actually fixed to the block, so you can't use it as a normal Type-C to Type-C cable. On the bright side, Google has used a cable which is around four feet long, so you get some extra length compared to using the included cable in the box. As you can see in the graph above, the battery is charged at around 11W while fast charging, which lasts for three hours before trickle charging begins. Getting the remaining 10-15% ends up taking another hour, with the total charge time from 0% to 100% being 4.14 hours. Considering that the Pixel C packs a noticeably larger battery than the iPad Air 2, the roughly four hour charge time is actually quite a good result.

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  • tipoo - Monday, January 25, 2016 - link

    Ars theorized that this was never meant to run Android...Reading this review, it seems to add some plausibility to that.

    http://arstechnica.com/gadgets/2015/12/the-pixel-c...
  • tipoo - Monday, January 25, 2016 - link

    Not that ChromeOS would really help on the app front, so Google is in a bit of a pickle.
  • testbug00 - Tuesday, January 26, 2016 - link

    ChromeOS would help a lot on the multitasking and functionality front. Think of it as a high end chromebook that has the ability to be used as a tablet.
  • marcryan - Monday, January 25, 2016 - link

    I just finished returning my Pixel C. I didn't have issues in connecting the device and keyboard nor did I have problems with Internet connectivity. But the major show stopper for me was the touch screen latency. It was insane how many times I had to touch the device to get it to respond. I even tried a stylus on the screen in a drawing program and the pixel was unable to track a straight line without breaks along the way where the screen did not register the input.

    Beyond that there was a supreme amount of waiting time for an app to respond after tapping on it on the home screen. I did a side by side with my Nexus 6P and the nexus (not without its own flaws) performed noticeably faster which is shocking considering the benchmark scores on the pixel C processor.

    There's something fatally flawed in the device which is unfortunate because I really wanted to like it, it's a nice piece of hardware.
  • evefavretto - Monday, January 25, 2016 - link

    Another interesting characteristic of the A-series, and by extension, Pixel C' screen is the fact that, once divided in half, the two remaining parts keep the same proportion: 1:√2.
    Probably a design choice for a multitasking feature that was scrapped from Chrome OS and now will see the light of the day in Android.
  • Dribble - Monday, January 25, 2016 - link

    Thank you for the NAND performance charts - I have been bitten twice by cheap and nasty NAND killing my tablet's performance after a year or two. I now won't touch one unless I know it's NAND is decent - and pixel C really is pretty borderline considering how high end it's meant to be.

    Agree google has software problems, although I would say it goes beyond missing features. It's clearly far to hard to keep something working as you upgrade. Almost every device I have owned has worked best on whatever version of android it came with. Every upgrade generally introduces problems. I get the feeling they developed the pixel c with android 5 and I bet it worked fine there, then they did an upgrade too 6 and now have all manor of niggles to sort out. Hence I am actually more drawn to devices that don't have major android version upgrades. I'll take an out of date but working version of android over the latest and greatest but slightly broken every time.
  • Dobson123 - Monday, January 25, 2016 - link

    There is a mistake in the chart on the first page: The Tegra K1 has 192 shader units, not 128.

    And do you know why they have disabled the A53 cores?
  • Kepe - Monday, January 25, 2016 - link

    Judging by the overall unfinishedness of the Pixel C, I'd guess migrating from the small cores to the big ones and vice versa causes some kind of a performance issue Google couldn't solve, as the Tegra X1 doesn't have heterogenous multi-processing.. So there'd be even more lag and performance issues than there is now.
    But perhaps it doesn't really even matter, since the big cores go as low as 51 MHz. It probably wouldn't save much power (if at all) if the little cores were used when there's a low workload. Battery performance seems to be really good even without the little cores.
  • Brandon Chester - Monday, January 25, 2016 - link

    Indeed you are right. I've corrected the error.

    As for the cluster migration, just keep in mind that the SHIELD TV doesn't do it either. Granted, that is plugged into the wall so power isn't a big deal, but it's important to note that we haven't see a single implementation where the A53s are used so I wouldn't be quick to blame it on the Pixel C specifically.
  • tipoo - Monday, January 25, 2016 - link

    For the SHIELD does it not do switching, or does it turn the A53s off completely? As something plugged into a wall and with overkill cooling for an ARM SoC, it may as well use all 8 all the time, no?

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