The iPhone XS & XS Max Review: Unveiling the Silicon Secrets
by Andrei Frumusanu on October 5, 2018 8:00 AM EST- Posted in
- Mobile
- Apple
- Smartphones
- iPhone XS
- iPhone XS Max
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.
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.
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iwod - Saturday, October 6, 2018 - link
> 480-500 mW when on a black screenAm I correct in understanding this figures in base "system" power? And not the display? There could be a case for more memory from iPhone 8, where the X had 3GB and Xs had 4GB.
Andrei Frumusanu - Saturday, October 6, 2018 - link
It's the power of the whole phone, meaning idle SoC, power delivery, and the screen and its controllers at an equivalent 0 nits brightness. Out of that figure some part will be the display, but we can't really separate it without tearing down the phone.The base power for the X and XS is near identical - the big difference is to the LCD iPhones.
iwod - Saturday, October 6, 2018 - link
Arh. That makes things clear. But why would OLED consume more power compared to LCD when it is completely off. This goes against common wisdom / knowledge OLED were suppose to be extremely efficient in all black display.Glaurung - Sunday, October 7, 2018 - link
"But why would OLED consume more power compared to LCD when it is completely off."This is addressed obliquely in the article - because the OLED display has high colour depth and extremely high DPI, it requires extra power to control all the levels of brightness for each and every one of those pixels.
eastcoast_pete - Sunday, October 7, 2018 - link
A few years ago, I loaded a "black Background" app on my trusty old Samsung S3. A black background always made a lot of sense to me for OLED-type screens. I might have missed it, but does Apple provide a black background setting in its settings for the XS and XS max? Also, I haven't seen much discussion about possible burn-in for OLED screens here or in other reviews of phones with OLED screens. Is this now a non-issue, maybe as many replace their phones before burn-in shows?ex2bot - Sunday, October 7, 2018 - link
No dark mode yet except for an incomplete one in accessibility settings. You end up with some graphics turned negative image. Hopefully, we’ll get a proper dark mode in iOS 13. The Mac finally got one.fzwo - Sunday, October 7, 2018 - link
If you activate Voice Over in Accessibility settings, you can triple-tap the display with three fingers to activate the „screen courtroom“, which makes the whole screen dark. I believe this turned off the backlight on LCD iPhones. Maybe it deactivates more than just displaying a black screen, and can help lower base power usage.Of course Voice Over being on may affect other behavior/benchmarks.
fzwo - Sunday, October 7, 2018 - link
Sorry, that should read „screen courtain“. Autocorrect is one area that seems to have gotten worse for me with iOS 12 😅eastcoast_pete - Monday, October 8, 2018 - link
Thanks for the information (I don't own an iPhone). The dark/black background I mean (and used to use on my S3 and later on a Blackberry Priv) didn't turn off the entire screen, so the icons were still bright, and appeared even brighter against the black background. I really wonder how much power one can save on phones like the iPhone X, XS and XS Max by using an unlit background. In theory, every lit pixel adds a little power drain, and every little LED not lit up should save that.AntonErtl - Saturday, October 6, 2018 - link
For me the most interesting part of the review is the SPECint results. Looking at the official SPEC report of the system with the highest base result (Cisco UCS B200 M5 (Intel Xeon Gold 6146,3.20 GHz), 4.2GHz Turbo), the A12 is really close; e.g., 44.56 (A12) vs. 48.3 (Xeon) for 403.gcc. An exception is 456.hmmer, but there Cisco (and many others) are using some compiler trick that you apparently are not using.
And the A12 is using quite a bit less power for these results than the Xeon. Very impressive of Apple. Maybe they should go into the server CPU business and produce the ARM-based server CPU that others have aimed for these last years.