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


View All Comments

  • MrGutts - Thursday, May 13, 2021 - link

    So let me get this right, the smaller version has a headphone jack but not the much larger unit? Reply
  • arashi - Sunday, May 16, 2021 - link

    The larger unit is literally the old version with updated SoC. Laziest upgrade. Reply
  • Kangal - Tuesday, May 18, 2021 - link

    The new QSD 888 isn't that much faster than the QSD 865, due to throttling. And the QSD 865 itself isn't that much faster than the QSD 855. Basically having QSD 855 in 2022 is still considered luxury/"flagship" level, unless you're in the iOS Market. With that said, the new "high-end" level chipset, QSD 780, is around the QSD 860 level. So that's a bargain. Maybe that's what ASUS should've gone for instead.

    After a year (or two), we should see a better, newer and optimised AndroidOS version, that is running on the next platform ARMv9. So I expect a good performance leap up from the QSD 888+, similar (probably better) to the performance leap from the Early QSD 845 to the Later QSD 855+.
  • XMight - Thursday, May 13, 2021 - link

    Looks cool phone, the kind I would use, but, has 2 drawbacks:
    1. no sd card slot. Its not the problem that 128 GB is not enough for me, its just having the possibility to store data outside internal memory and access it fast without plugging the phone in a PC.
    2. No FM radio in Europe. I'm tired of this, honestly. I look forward when Europe will force by law, like US, phone manufacturers to include FM radio. I really enjoy FM radio and even if I have unlimited plan, FM radio sounds way cooler and it feels more real-time than internet radio with apps with lots of ads and bloatware. Radio on Nokia 5 sounds really cool. I waited for Sony 5 III, which could have been my next phone, but no radio. Sony 10 III has no gyro, and I look at the stars with the phone through stellarium.

    And the whole issue is that there isn't a single phone on the market that has: SDCARD, FM RADIO, dualsim, GYRO, Snapdragon CPU, IP rating, 3.5mm, small form-factor at the same time. So, I will stick to my Nokia 5 and Sony XZ1 compact combination for a few more years. I really hate this marketing crap the companies are pulling for forcing people buy something they aren't 100% satisfied with at the moment so they will feel incentivized when a new phone with something they wanted appears, but misses something else they had before.
  • msildoja - Monday, July 5, 2021 - link

    Totally agree with the second part. No good compact phone on the market. Purchased xperia 5ii but returned it as it was too long. Went for asus zf8, but it has so poor battery life compared to xpetia 5ii. Sad. Reall no good phones available after sony ditched the compact series. Reply
  • yetanotherhuman - Friday, July 9, 2021 - link

    Yeah, it's incredibly tiring. I recently got a new phone, but it was too big. I left it in the box and carried on using my 4 year old phone instead. Reply
  • patel21 - Thursday, May 13, 2021 - link

    Hi Andrei,
    Wouldn't a 870 or even 865 make more sense in a compact phone like this which isn't able to use 888 to its fullest?
    They could even shave off a bit from price and the battery would also last longer
  • sheh - Thursday, May 13, 2021 - link

    Roughly the same size as the S10 and S20.
    A good start, but shaving extra 2-3mm width and 10mm height would be welcome.
  • tkSteveFOX - Friday, May 14, 2021 - link

    Strange, other reviews praise the camera for the price, but I also looked at their photos and more willing to go with your assumption.
    Ultrawide especially was lacking in fine detail even in broad daylight, and there's too much sharpening going in postprocessing. The main camera looks decent, but got to be expecting better than IMX686, however the front camera is miles better than anything in that price range.
  • SolarBear28 - Friday, May 14, 2021 - link

    This is pretty much the size and price I'd want for my next phone. My 2018 Galaxy A8 is a fantastic device and still getting quarterly security updates. I'd like to stick with Samsung for their Good Lock and One Hand Operation apps but they don't makes any good phones under 6" anymore. The S21 is a fantastic device but slightly bigger and slightly more expensive than I'd like. Reply

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