Battery Life - A Stark Contrast

We extensively covered the performance of the Snapdragon and Exynos Galaxy S9’s – what remains to be seen is how that performance affects battery life in our standard tests. Performance between the regular and larger Galaxy S9 doesn’t change, however battery life may differ based on the variant as the regular S9 sports a 3000mAh (11.55Wh) battery versus the 16% higher 3500mAh (13.47Wh) of the Galaxy S9+. Naturally the 14.2% bigger screen area of the S9+ offsets some of that advantage.

Unfortunately for this review we couldn’t get identical variants of the different SoC Galaxy S9s – our S9+ is a Snapdragon 845 unit while our S9 is an Exynos 9810 unit, so we weren’t able to execute a true apples-to-apples comparisons between the SoC variant, however as we’ll see the delta between the units is large enough that it won’t change the conclusion.

Our web browsing test tries to mimic real-world usage patterns of browsing websites. This includes iterating through a list of websites and scrolling through them. In this test, screen efficiency and battery size play a role, but also we balanced it so that it also sufficiently stresses the SoC (CPU, GPU and display pipeline) as well.

Web Browsing Battery Life 2016 (WiFi)

The Snapdragon 845 Galaxy S9+ posted excellent battery life in our test and lands only third to the iPhone 8 Plus and the Mate 9. Unfortunately we never tested the S8+ to see the generational difference, but it shouldn’t be too different from the S835 regular S8 at around the 10 hour mark.

The Exynos 9810 Galaxy S9 absolutely fell flat on its face in this test and posted the worst results among our tracking of the latest generation devices, lasting 3 hours less than the Exynos 8895 Galaxy S8. This was such a terrible run that I redid the test and still resulted in the same runtime.

I investigated the matter further to try to see if this was caused by the high energy usage of the M3 cores – and it seems it is. Enabling the “CPU limiter” (S9 PS result in the graphs) which is found in the battery optimisation options of Samsung’s firmware greatly throttles the M3 cores down to 1469 MHz, memory controller to half speed and also seemingly changes some scheduler settings to make them more conservative. This results in peak performance equal to the Exynos 8895- however the scheduler alterations also noticeably slow down UI responsiveness so it’s actually a worse experience. Nevertheless, backing off on performance results in regaining almost 3 hours.

This is such a terrible battery performance of the Exynos 9810 variant that it again puts even more clout into the new SoC. My theory as to why this happens is that not only do the higher frequency state require more energy per work done than competing SoCs – because this is a big CPU complex there’s also lots of leakage at play. The DVFS system being so slow might actually be bad for energy here as we might be seeing the opposite of race-to-sleep, walk-to-waste. The fact that Apple’s SoCs don’t have any issues with battery life in this test showcases that it’s not an inherent problem of having a high-power micro-architecture, but rather something specific to the Exynos 9810.

PCMark Work 2.0 - Battery Life

In PCMark the disadvantage of the Exynos 9810 S9 isn’t as pronounced as in the web test, however it’s again a regression to the Exynos 8895 S8 – all while not posting a meaningful performance advantage over its predecessor that might explain the lower battery life.

The Snapdragon 845 Galaxy S9+ fared relatively well, even though it’s not quite as good as other devices.

In my personal every-day usage I can’t saw that I noticed a massive disadvantage in battery life on the Galaxy S9, however my everyday usage is relatively light and I haven’t had enough time with the phone yet as a daily driver to make a final judgment. I did notice that the Exynos 9810 does shows signs of suffering in heavy tasks. Instances of Gmail syncing my inbox with a new account did once result in a warm phone while the Snapdragon 845 Galaxy S9 did not showcase this characteristic.

I can’t fault the Snapdragon S9+ in the time I had it, but again I haven’t had enough real time with it to really judge it subjectively. As far as AnandTech testing goes, the data speaks for itself and based on what I’ve seen I strongly do not recommend the Exynos variant of the Galaxy S9 in its current state, especially if you’re a regular user of heavy apps.

Over the coming weeks I’m planning to try to dive into the workings of the Exynos 9810 and post a follow-up article on whether it’s possible to improve both in terms of performance as well as battery life if one changes the way the SoC’s scheduler and DVFS works. In the eventuality that Samsung updates its firmware to resolve these large issues with the Exynos Galaxies, then we’ll revisit the matter as soon as possible.

Display Evaluation & Power Camera Architecture & Video Performance


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  • peevee - Friday, April 6, 2018 - link

    Essential 2?
    Given small real-life difference between 845 and 835, Essential PH-1 is still a great device. And very appropriately priced. Nothing to wait there.
  • StrangerGuy - Tuesday, March 27, 2018 - link

    All the S9 did was made me appreciate my S8+ more, of which I only bought because of generous employer benefits. Without which I wouldn't even have cared about these overpriced flagships. Reply
  • Valantar - Tuesday, March 27, 2018 - link

    I pointed this out in your S9 launch article, and apparently I have to make my point again: neither light nor depth of field is the reason for the aperture change - it's purely to combat distortions and lack of sharpness in the image due to the combination of a large aperture and tiny, tiny glass.

    Why? When it comes to depth of field, one needs to factor in not only the aperture, but also the crop factor (sensor size relative to standard 35mm film). As such, f/1.5 on a standard cell phone 1/2.3" sensor is roughly equal to f/8.4 on a 35mm sensor, or f/5.6 on an APS-C sensor. This is one of the main photographic advantages of large-sensor cameras: that you can get shallow depth of field with lenses that are actually possible to manufacture.

    An example:
    As you can see here, with a 1/2.3" f/1.5 sensor, focusing on a subject 3m away gives you an in-focus area of ~43m - this is NOT too little, not by any measure. Moving the subject to 5m gives you effectively infinite focus, with everything from 1.9 to infinity being in the focal plane. You'd need your subject at less than .5 meters for DoF to be an issue - which it would be with most cameras at that distance.

    On the other hand, it's well known that for large apertures, anything but the best glass will lead to aberrations and distortions in the image, and a general loss of sharpness across the frame. Look at even a single DSLR lens review - they're _always_ sharper when stopped down. With a lens stack this tiny, there's no feasible way to control this - it's likely physically impossible to avoid aberrations and distortions at an aperture number like this. Hence, the variable aperture.

    Now, AT is usually very accurate in their reporting. Could you PLEASE correct this? Pretty please? Since you claim to be doing a deep-dive into the camera, this is not a good look.
  • Valantar - Tuesday, March 27, 2018 - link

    To clarify: You say that "The F/2.4 aperture in day-light shots is not a gimmick and very much an advantage to the S9 as its deeper depth of field is noticeable in shots, producing sharper images than the F/1.5 aperture." This is a misunderstood conclusion. The added sharpness is largely not due to a deeper depth of field, but rather due to the stopped-down aperture resulting in a generally sharper image. This conflates two different characteristics, focus depth and lens/optical sharpness. These are not the same. If you did a more rigorous test where both cameras focused on the same spot (ideally not in the centre of the image) in a scene with sufficient depth, or conversely shot against a flat target with a lot of detail, you'd likely see this pretty clearly, as _even the focal point_ would be sharper at f/2.4. If this was due to depth of field, both settings would be equally sharp at the focus point, while what you're saying here is that f/2.4 is sharper _across the image_. That's a typical effect of a smaller aperture improving sharpness, not of the smaller aperture restricting DoF. Reply
  • peevee - Friday, April 6, 2018 - link

    " _even the focal point_ would be sharper at f/2.4"

    If it is the center, it might not be so because with such tiny sensor, at f/2.4 maximum resolution is diffraction-limited. Need the exact size of the sensor to confirm, but I am almost sure than even at f/1.5 Airy disk is bigger than a pixel.
  • Takethis - Tuesday, March 27, 2018 - link

    Any chance they Samsung could fix their “slow-and-steady” DVFS approach with software updates? Given the actual state of things, Snapdragon 845 phones are the one to buy this year (I'm thinking Oneplus 6) Reply
  • Ankurg - Tuesday, March 27, 2018 - link

    With due respect to the author and the site, I have to believe that most of the extensive tests and their results will not affect the avg day-to-day usage of this device.

    I am already seeing the panic this review has created on reddit, with many people now re-thinking whether to purchase or not...

    Yes, most youtube/site reviewers don't go as deep as this, but a problem so steep would have been felt.

    I would advice my fellow mates here not to lose sight of the fact that this is the best android phone you can buy right now.....irrespective of the choice of chip.
  • SirCanealot - Tuesday, March 27, 2018 - link

    "With due respect to the author and the site, I have to believe that most of the extensive tests and their results will not affect the avg day-to-day usage of this device."

    While I'm happy to have a super-fast phone with crappy battery life, I'm not happy to have an average-speed phone with crappy battery life. IE, I have a Exynos Note 4 which is fast with crappy battery life and it still does the job...

    The crappy battery life is going to effect every single user and every one of your friends in America is going to get a better performing phone with better battery life. Day-to-day I'm getting worse performance and battery life; this means I can re-consider my options now I have all the data.

    Why shouldn't this review make you reconsider? That's what it's meant to do. Unless you're a Samsung shareholder, I wouldn't pay any attention to this completely normal thing of human society...
  • id4andrei - Tuesday, March 27, 2018 - link

    The author himself stated that you will not see any difference as an ordinary consumer. Some slight circumstantial scrolling stutters are all he noticed.

    Still the Exynos underperforms relative to its advances in chip design.
  • peevee - Friday, April 6, 2018 - link

    "The author himself stated that you will not see any difference as an ordinary consumer."

    Nope. The fast core only winding up after 0.4s is VERY noticeable as good phones will already finish launching an app or rendering a local HTML in Webview by this time, some time ago.

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