Samsung Galaxy S20+ & Ultra (Snapdragon & Exynos) Battery Life Preview

[harlan4096]

Last week we brought you a quick performance preview of the Snapdragon 865-based Samsung Galaxy S20 Ultra, showcasing that the phone has some outstandingly good performance and power efficiency statistics. Since then, we’ve been able to get our hands on an Exynos 990 based Galaxy S20+ and S20 Ultra, putting the trio of phones through our usual extensive review process.

We’re still working on the full big article which is still a week or more away, but we wanted already to cover one largest talking points about the new devices: battery life. Samsung’s new 120Hz refresh mode is quite a power-hungry beast, which alters the battery life formula for this year’s flagships. On top of that, we’re again seeing some quite large differences between the Exynos and Snapdragon based phones, and we’re able to report the first preliminary battery test results and analyse what the situation looks like.

Read More:

• Samsung Galaxy S20 Ultra (Snapdragon 865) Quick Performance Preview: Impressive
  
• The Snapdragon 865 Performance Preview: Setting the Stage for Flagship Android 2020
  
• Samsung Announces The Galaxy S20, S20+ and S20 Ultra: 120Hz, 5G, Huge Batteries, Crazy Cameras and $$$
  

Editor's Note: The current results were tested on the ATBM firmwares for the Exynos variants, and ATBN for the Snapdragon variant.

Very Expensive 120Hz Mode, Power Degradations Across The Board

One key aspect of the new Galaxy S20 devices is their new 120Hz screen display mode. Samsung’s new high refresh rate is undoubtedly a killer feature for the new flagships, and when it comes to the performance as well as the fluidity it brings, it’s an incomparable experience that only very few devices can compete with.

To achieve this performance, Samsung seemingly has had to make some sacrifices when it comes to the power consumption of the phones. While Samsung has managed to implement the 120Hz mode without any additional hardware such as additional MIPI interfaces between the SoC and the display controller IC (hence, why it’s limited to 1080p 120Hz), the actual power management and power draw when in the 120Hz mode is extremely inefficient and not very optimised.

On both Snapdragon and Exynos units there’s evidence in the display drivers that there’s hardware support for some sort of VRR (Variable refresh rate) – what exactly this VRR implementation represents I currently don’t have further information on, but it doesn’t seem that it’s a “true” VRR mode, at least not in the current software state of things. Samsung has the panel implementation set up with seemingly 4 different refresh rates; 48Hz, 60Hz, 96Hz and 120Hz. Seemingly, it’s possible this VRR implementation is switching between these modes?

There’s also evidence of an unfinished software stack; seemingly Samsung had planned for some sort of adaptive 120Hz mode, however currently this seems to not be active and the phone simply stays at 120Hz all the time.

What’s worrisome here is that the 120Hz mode has quite a large power impact that’s active at all times, no matter the screen content. Above for example we see the baseline power on the S20 Ultra with the Exynos 990. Both highlighted regions are on a static black screen, and there’s a huge ~184mW difference between the two modes. 184mW might not sound like much, but given that this is a baseline power consumption of the phone that’s always present whenever you have the screen on, it adds on to a considerable amount of energy over a whole battery charge.

This delta between the 60 and 120Hz mode is present on all the S20 devices I have at hand here, both on the Exynos 990 S20+ and S20 Ultra, as well as on the Snapdragon 865 S20 Ultra:
...

Continue Reading