Battery Life

The iPhone XS comes with a 2658mAh/10.13Wh battery, while the XS Max has a capacity of 3174mAh/12.08Wh. Again, it’s to be noted that although both phones are quite large form-factor devices by now, Apple’s battery density still largely lags behind the competition. While yes, it’s true that the XS Max’ battery is the biggest that Apple has ever used, it still pales in comparison to the 3500 to 4000mAh that other vendors now employ in the same form-factor.

As we saw in the SPEC analysis, the one advantage that Apple has is an enormous lead in terms of power efficiency of its SoC, which largely makes up for any gap in the battery capacity deficit.

Our web browsing test is a mixed-to-heavy workload that iterates through a set of popular webpages that are hosted on our server. The test loads a web page, pauses, scrolls through it, pauses, and then continues to the next in the set, repeating all over when done. Brightness is fixed at 200cd/m².

Web Browsing Battery Life 2016 (WiFi)

The iPhone XS saw a very slight degradation compared to the iPhone X in our test. The 19 minute deficit isn’t terrible, but it does come at a surprise given that Apple had promised improved battery life for the new model. What’s happening is that likely our test is a tad heavier in its workload than what Apple and many other vendors internally test to advertise as the daily battery life of their devices.

The iPhone XS Max came in at 10.3h. Again while this is still good, it’s a degradation over the 11.83h of the iPhone 8 Plus. Here it’s easier to rationalise the difference; the OLED screen of the XS Max is just more power hungry and also has a larger area than the iPhone 8 Plus. Here the increased battery capacity isn’t enough to counteract the panel’s increased needs.

As to why the iPhone XS saw a degradation over the X, I’m not too sure. I did rerun the test on the iPhone X to make sure iOS12 hadn’t impacted the devices – and I got a runtime just 10 minutes lower than what I had tested on the iPhone X back around in January, so the iOS upgrade certainly doesn’t seem to have affected the battery life.

It should be relatively safe to assume that the new A12 should be more efficient in its workloads, even with the increased performance that it brings. One thing that we can’t really verify is the power efficiency at intermediate performance states, as that’s also where CPUs perform a lot of their work at.

We also have to keep in mind the connectivity factor: the new iPhone’s seems to sport a new Broadcom BCM4377 WiFi combo chip which we don’t know much about. Most importantly the new XS have also switched over from a Qualcomm baseband (in our test unit of the iPhone X) to a new Intel XMM7560 baseband.

I’ve generally given up on LTE testing after a few years ago I had run into some serious issues regarding a misconfiguration of my mobile carriers’ baseband stations as they did not have CDRX enabled. This caused an almost 20-30% battery life degradation on Huawei’s devices – and if I hadn’t debugged the issue with HiSilicon I’d probably be none the wiser. Fact is, cellular battery life testing is a lot harder than one would think, and without having a controlled environment, I’m very hesitant to resume cellular battery life testing.

That being said, I will revisit the iPhone X vs iPhone XS battery life topic while on LTE over the weekend and post an update to the review.

Overall, the battery life of the iPhone XS and XS Max are good – they don’t quite reach Apple’s claimed improvements, but that also just might be something that will vary from use-case to use-case.

Display Measurement & Power Camera - Daylight Evaluation: Zoom and Scenic
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  • Constructor - Monday, October 8, 2018 - link

    Sure you can – just go to airplane mode and re-enable WiFi.
  • s.yu - Monday, October 8, 2018 - link

    In the third and fifth low light sample I think it's pretty clear that the XS beat the P20P, again P20P's retention of texture is horrible and only in extreme low light (second and last sample) and scenes with many man-made objects which lack obvious texture (third sample) does its excessive sharpening and NR have a advantage. The first sample is a surprise, there either the scene is actually darker than I'm lead to believe or there's something else I've not taken into account.
  • daiquiri - Monday, October 8, 2018 - link

    Isn't this a too bold affirmation that A12 is on par with current desktop CPUs? So why didn't we stack them in order to have 5x the processing power of a common laptop/workstation for 1/2 of the power? What am I missing here? Because this doesn't make much sense to me.

    If I have 2 or 3 of these SoC chips and photoshop running on them will I have my filters running faster? Chrome loading webpages faster? Creating zip archives or converting flac files 3x times faster than an Intel I7?
  • resiroth - Monday, October 8, 2018 - link

    There is widespread speculation (and at this point, it is considered more likely than not) that apple will transition to their own chips exclusively for their Mac products in the near future (within 2 years).

    What exactly doesn’t make sense to you?

    Ps: will be very interesting to see results of new iPad Pro this year too.
  • daiquiri - Monday, October 8, 2018 - link

    What is strange to me is why aren't we already stacking this SoCs. I suppose I can fit 6 or 8 of these processors on the same die size. This means I would have a lot faster PC for less power? It they are that great why aren't on desktops already?

    Does this mean if I manage to install Windows 10 ARM edition on my PC photoshop will run faster and Chrome will load pages two or three times faster since I have 8 of these SoCs on my desktop pc?
  • Constructor - Wednesday, October 10, 2018 - link

    Because just increasing the core count is not quite enough.

    As I have explained above, a platform transition is a massive undertaking which among many other things needs actually superior performance to afford the initially still necessary legacy code emulation.

    This will almost certainly start at a WWDC (next year or the year after that, most likely) with an announcement about not just coming hardware but also about those new mechanisms in macOS itself, and actual Axx-powered Macs may take months after that to emerge while developers start porting their code to the new platform.

    It's not as if this was the first time for Apple – they've done it twice already!
  • varase - Tuesday, October 23, 2018 - link

    Yeah, but they always went to a *much* faster CPU to do the emulation.
  • Constructor - Wednesday, October 24, 2018 - link

    Even just the iPhone cores right now are already at about a desktop i5 level according to GeekBench.

    There should be quite some room for upscaling with more power and better cooling.
  • tipoo - Wednesday, October 24, 2018 - link

    These cores are 30% larger than Intels, let that sink in.

    I'm sure 8 of them would perform marvellously, for the cost. And it may be coming.
  • Zoolook - Tuesday, October 9, 2018 - link

    I just pulled an old test of a i3-6320, a 3 year old dual-core, and the A12 does good on some of the tests, but in many tests it's quite a bit behind, so it's not ready for server-duty yet.

    I know that the i3 has higher frequencies but it's also only two cores, compared to 2+4.
    There is no question that the big cores are very efficient, but they are optimized for their current job.

    If Apple would build a 6- or 8-core processor based on their large cores and throw away most of the other SoC and add other parts (stronger SIMD etc), yes then we might have a good desktop/serverchip, but the A12 is not that chip.

    Also remember that we are comparing 14nm Intel chips with the newest "7nm" process, if Intel ever gets their 10nm process up and running for real, then we could do a better comparison.

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