Battery Life

The Zenfone 8 features a contemporary 4000mAh battery, which considering the size and 169g weight of the phone is actually quite respectable and competes well with other alternatives in the market.

The features that might impact the battery life of the phone are the Snapdragon 888 SoC, less efficient than its predecessor, as well as the 120Hz display which lacks any more advanced power management. The latter aspect of the phone can be quite negative – while the 60Hz mode of the phone has an underperforming base power consumption of 615mW, the 120Hz mode raises this to a rather eye-watering 783mW on a full black screen at minimum brightness.

Anecdotally speaking, I’ve seen vast power regressions on almost all Snapdragon 888 flagship devices this year, all except for Samsung’s S21 Ultra. The Mi 11, Mi 11 Ultra, OnePlus 9 Pro, ROG Phone 5 all exhibit quite bad base power behaviour, and the only difference to the S21 series is that Samsung employs Maxim PMICs and Broadcom WiFi solutions rather than Qualcomm’s own chips. I don’t know if there’s a correlation there or not, but the Zenfone 8 shows similar lacklustre efficiency.

Web Browsing Battery Life 2016 (WiFi)

In the web-browsing test in Auto mode which switches to 90Hz inside of the browser, the Zenfone 8 tracks rather closely to the Zenfone 7. The predecessor has a 25% larger battery, but also has a much larger display. The contemporary comparison to make is the smaller Galaxy S21 which lands ahead of the ZF8 even though it runs at 120Hz mode, and far ahead at 60Hz.

I’ll be updating the article with fixed 120Hz and 60Hz results for the ZF8 in the coming days.

PCMark Work 2.0 - Battery Life 

As noted in the performance section, “Auto” mode actually fixes itself to 60Hz in various applications, such as PCMark. The ZF8 here in its best-case scenario lands actually quite well in the relative positioning, meaning battery life in this mode is relatively competitive.

Again, I’ll be completing the result set with other refresh rate modes in the comings days.

Generally speaking, the Zenfone 8 finds itself in a tough situation when it comes to battery life. The 90Hz and 120Hz modes are really inefficient due to extremely lacklustre base power consumption behaviours. If you were to use your phone at very high brightness levels, the luminance power would vastly overcome that disadvantage and one probably wouldn’t notice the deficit as much, but at lower brightness levels, the phone would last much less than comparative devices.

The conundrum with this situation is that while 60Hz seems to be efficient for the Zenfone 8, it’s also not an as quite good experience when it comes to performance and responsiveness. So either you’ll have to deal with a responsive and inefficient device, or with an adequate battery life but sluggish feeling phone.

GPU Performance Camera - First Impressions
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  • Linustechtips12#6900xt - Thursday, May 13, 2021 - link

    I do get it inefficient and I don't use it other than with dex but it something that's nice I was at a colts game and there was a wireless charging pad available for everyone and it happened to be i was without a charger and at about 20%, its just a convenience like a micro-sd or a headphone jack. Reply
  • nico_mach - Wednesday, May 19, 2021 - link

    I think the drawbacks are overstated. I used wireless charging nightly on my s8 and the battery is still fine all these years later. The software, otoh... Reply
  • ads295 - Thursday, May 13, 2021 - link

    I'm really liking this thing by the looks of it. IP rating + headphone jack + compact size + 4000mAh battery is a winning combination. Hope they work on the camera though, I'm sure the mediocrity lies in the software rather than the hardware. Reply
  • skydiverian - Thursday, May 13, 2021 - link

    Can't stand notches or holepunch displays (i.e. I only want displays that are symmetrical on 2 axes - my Pixel 3a tbh still annoys me with rounded corners. Talking of the 3a, it's as big as I want to go. Guess I'll be holding onto it for the next 10 years at this rate. Otherwise this could be a contender for a replacement but I just can't stand that holepunch. Reply
  • Spunjji - Thursday, May 13, 2021 - link

    I hated them at first, but got used to a notch after 2.5 years of owning a phone with one. Now have one with a punch-hole, I'd say it's neither an improvement nor a step back. I'd still prefer a top and bottom bezel and better front-facing speakers, but it's not the end of the world. Might be worth contemplating when it becomes time for a replacement. Reply
  • inperfectdarkness - Sunday, May 16, 2021 - link

    This is why I love the Xperia XZ2 Compact. Bezels. The 18x9 form factor just looks better and feels better. Reply
  • c933103 - Thursday, May 13, 2021 - link

    No. A 68-69mm wide phone is not compact. I have tried Xperia X Performance and Galaxy S10e. They don't fit in single hand. Now Zenfone 8 and Xperia 5 series are all trying to pretend they are compact but they aren't. The only option remaining is to spend 700USD to import an Aquos R2 Compact with Snapdragon 845 from Japan, or buy the Xperia XZ1 Compact with Snapdragon 835, for someone in Android ecosystem. Reply
  • ads295 - Thursday, May 13, 2021 - link

    Both those devices aren't even in sniffing distance of 3000mAh battery capacity. Good luck with your battery life. At least the Sony uses 720p resolution which should help battery life, but the Aquos should be really mediocre with that high end chipset, high res display and relatively tiny battery size @2500mAh. I agree that phones could be still smaller but now we're talking about a fraction of an already small percentage of consumer base overall who want small phones. Reply
  • hemedans - Thursday, May 13, 2021 - link

    xperia xz1 compact has best battery life than most flagship, better than many 4000 and 5000mah phones, usually i get 10+ hrs of on screen time. sd 835 was efficient and 720p help a lot. Reply
  • inperfectdarkness - Sunday, May 16, 2021 - link

    2700mAh for xz1 compact. 2870mAh for xz2 compact. Reply

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