Battery Life: Good (60Hz) to Average (120Hz)

Last week we had published our initial battery life report on the S20 series, with some interesting findings. First of all, what needs to be mentioned again is that the new 120Hz display modes on the phones come with a quite large battery life impact. The behavior is exhibited on all our S20 models at hand and I think it’s likely due to the panel itself or the DDIC. Samsung had included various display refresh modes varying from 48, 60, 96 and 120Hz, however we have yet to find evidence of any mechanism that actively switches between the various modes. 

Device-On Black Screen Power Consumption (Airplane Mode)

As such, even on a black static screen, running at 120Hz comes with a quite steep power penalty that’s always present whenever the display is on, costing around 160mW of power.

I had noted that I found our variant of the Snapdragon 865 Galaxy S20 Ultra to have worse idle power than our Exynos phone version. Initially I had attributed this to possibly the SoC or even the nature of the external X55 modem, but since then I’ve also received an LG V60 and that device’s idle power is perfectly normal. The only other thing that differentiates our S20 Ultra here is the fact that it has the extra mmWave antennas and RF systems. It would be interesting to see if non-mmWave variants of the Snapdragon S20 Ultra behave any differently (Tip at our Chinese or Korean readers).

I also had made mention that the “Performance” mode of the Exynos S20 phones seemingly behaved quite overzealously in terms of its scheduling settings, and there was a quite drastic increase in power draw for what was not nearly an as drastic increase in performance. I’ve rerun the battery tests in the “Optimized” settings which doesn’t have the “Increased system speed” option enabled, and I’ve confirmed my suspicion as the battery life figures did improve by some notable amounts. I’ve also tested the Snapdragon in the “Optimized” setting and the runtimes only differed by 2% - for users having the Snapdragon versions it’s thus safe to simply leave that enabled.

Web Browsing Battery Life 2016 (WiFi)

In our web test, the new S20 series end up right about where you’d expect them to. The Snapdragon 865 Galaxy S20 Ultra at 60Hz fares the best amongst the tested models, and now represents Samsung’s longest lasting flagship device. Slightly behind it we find the Exynos S20 Ultra at 60Hz. The difference between the two phones here isn’t very big in this test, and I attribute this to the higher constant idle power draw of the Snapdragon phone which counteracts the much higher compute efficiency of the SoC. The Eyxnos S20+ ends up slightly behind the S10+ phones, but still lasts a good 12.65h in this test.

Once we turn on the 120Hz display modes, the battery life results on all the phones drops quite notably. The Snapdragon S20 Ultra goes from 14h to 11.3h, a 20% drop. The same applies to the Exynos S20 Ultra, with a 20% drop, but for some reason the S20+ sees a larger drop of 25%. In the systems performance section I did mention that there’s some software configuration differences between the Exynos S20 Ultra and S20+, maybe some of that plays part here in the results.

PCMark Work 2.0 - Battery Life

Overall, the conclusion on battery life isn’t quite as black & white as we thought it would be. The key point is to stay away from the seemingly broken Performance mode on the Exynos chipset and you’ll have roughly similar battery life results between the two SoC variants of the S20. Naturally, that’s only being achieved by the fact that the Exynos does showcase worse performance, saving energy by using the more efficient lower performance states more.

What’s valid for all variants of the phones is that the 120Hz display mode is quite the power hog. Samsung probably has the opportunity to improve this by introducing a better managed variable refresh rate mode that actually changes between the different refresh rates based on content, something that seemingly isn’t happening right now. Also switching to lower refresh rates when showcasing static content would be a huge power saver, but I’m not sure if Samsung would be able to actually deploy such a mechanism.

Display Measurement Camera Architecture: Huge New Sensors
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  • katakuri4744 - Wednesday, April 8, 2020 - link

    Hi Andrei,
    Appreciate such a detailed article. I have one question, how did you pull the voltage curve, is there a command?
    I had S10 exynos then upgraded it to S20+ exynos, both the articles had this voltage curve though the Snapdragon variant does not, I would like to check the same for my device as well.
    Reply
  • helloworld_chip - Monday, April 6, 2020 - link

    Though 865's compute efficiency loks pretty good, from some other data points I heard that its infrastructure power (impacting real user-daily activities, light-loaded scenarios) is quite BAD. Would be good if more such comparisons are available to confirm this, since it determines how long people can actually use a phone. Reply
  • s.yu - Monday, April 6, 2020 - link

    Idle is relatively inefficient and the numbers here show. Reply
  • helloworld_chip - Monday, April 6, 2020 - link

    Gotcha thx.

    I am thinking we should calculate bat-capacity / hours instead of just hours to really show how is the SoCs overall efficiency.

    Bigger and Bigger battery really make us feel heavier, we should push the designer harder to make these more efficiency instead of just using larger and larger battery.
    Reply
  • FunBunny2 - Tuesday, April 7, 2020 - link

    "Bigger and Bigger battery really make us feel heavier, we should push the designer harder to make these more efficiency instead of just using larger and larger battery. "

    last time I looked, most of the battery goes to driving the screen. so resurrect your original iPhone. the notion that batteries will have increasing power density this millennium is fantasy. Li is the smallest source of electrons available. well, unless you're willing to carry around a Hindenburg in your pocket.
    Reply
  • s.yu - Tuesday, April 7, 2020 - link

    Technically I'm with you but I just don't trust all developers to sufficiently optimize their code. You see that Peachncream guy who always claims that his dinosaur fossils run everything smoothly but it just doesn't happen to me. The way it is my S6E(backup device) that literally runs 3 apps in all(not even simultaneously, AFAIK) with animations turned off in dev mode is much slower than his...some really old low end phone, same thing with the battery, a large capacity gives me peace of mind over any optimization because I know that nothing could eat through the battery too fast. Reply
  • watzupken - Monday, April 6, 2020 - link

    This is the reason why I will not consider any Samsung Galaxy phone that is running on Exynos SOC. If it is on the low/ mid end, I can't complain about it. But when shelling out for a flagship, I don't see why one would pay the same amount for the slower variant and you don't have the choice to get the superior version locally. Reply
  • andyfrut - Monday, April 6, 2020 - link

    Is the S20+ (855) comparable with the S20 Ultra (855) in battery life in 120hz? Reply
  • andyfrut - Monday, April 6, 2020 - link

    snapdragon 865* Reply
  • Ayaan_G - Tuesday, April 7, 2020 - link

    The 5G addition to the Samsung Galaxy series will really give it a boost in another level ! Reply

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