Note: This article was first published on 29 May 2019.
The problem with battery tests
The great thing about notebooks is they let you work anywhere but not if it runs out of juice.
Testing any device’s battery is not as easy as it sounds, especially if it’s a notebook. To begin, a notebook is an extremely multifaceted device that can do many things. It can be used for work, it can play games, and it can show videos, and each task affects its battery life in different ways.
And then there’s the matter of manufacturer’s claims. Each manufacturer measures and reports their notebook’s battery life differently, making it hard to draw any kind of meaningful conclusion.
Should we and can we believe manufacturers' claims? (Image source: LG)
Here’s ASUS testing methodology when quoting the battery life of VivoBook S14:
Battery tests conducted by ASUS in July 2018 using local video playback. Test settings: Wi-Fi enabled, display brightness set to 150nits, and volume at 50%.
And here’s HP for the Spectre X360. Very specific and detailed but different from others:
Battery life tested by HP using continuous FHD video playback, 1080p (1920x1080) resolution, 150 nits brightness, system audio level at 17%, player audio level at 100%, played full-screen from local storage, headphone attached, wireless on but not connected.
And then there’s Apple’s:
The wireless web test measures battery life by wirelessly browsing 25 popular websites with display brightness set to 12 clicks from the bottom or 75 per cent. The iTunes movie playback test measures battery life by playing back 1080p HD content with display brightness set to 12 clicks from the bottom or 75 per cent. The standby test measures battery life by allowing a system, connected to a wireless network and signed in to an iCloud account, to enter standby mode with Safari and Mail applications launched and all system settings left at default.
And some, like LG, are quite vague about how they measure battery life. This is the footnote for their LG gram notebook:
Battery life can vary, depending on the model, settings, and user environments based on the MobileMark® 2014 standard.
To be clear, there’s nothing wrong with the way their notebooks are tested — the test parameters used are entirely plausible. It’s just that they are inconsistent so there's no way of drawing any kind of worthwhile conclusion between each manufacturer’s claims.
Introducing PCMark 10's new battery benchmark
PCMark 8 was a useful tool for testing battery life but its parameters were too general.
So to address this issue, we need a benchmark that is consistent and produces repeatable results.
Our old battery testing benchmark, the Home workload in PCMark 8, was good in that respect. But its parameters are too broad and probably not entirely representative of most use cases.
It runs a workload that cycles through the following:
- Web Browsing
- Writing
- Casual Gaming
- Photo Editing
- Video Chat
While web browsing and productivity are fairly common use cases, the remaining three are less so. Furthermore, they put a great strain on the battery, which gives us results that are a little skewed. While it’s fair to say that the final results represent the “worst-case scenario,” the same argument could be made that they are not entirely representative of normal use cases. That's because, as we will find out later, the worst-case scenario battery life and the battery life that you will normally get if you use a notebook sensibly is very different.
So what then are normal use cases? We have identified this to be web browsing, productivity, and video watching.
PCMark 10's new battery profiles aim to more accurately mimic real-world usage.
This brings us to the latest version of PCMark 10 which adds a much-requested battery test feature that was designed to more accurately mimic real-world usage by offering a couple of test scenarios.
These are the test scenarios and what they represent according to UL Benchmarks (the people behind this benchmark, also previously known as Futuremark) :
- Modern Office: Battery Life for everyday work
- Applications: Battery Life for Microsoft Office
- Video: Battery Life playing back HD Video
- Gaming: Battery Life while gaming
- Idle: Runtime at idle
The ones we are most interested in its Modern Office, Video, and Gaming. There’s some overlap between Modern Office and Applications since the former includes web browsing and word processing, which is also tested under the Applications workload. However, Modern Office includes video conferencing which makes for a more varied run, whereas Applications solely runs productivity workloads which is too specific in our opinion.
The Video workload will give users a good idea of how long the machines will run if they only want to binge on movies and shows. Finally, the Gaming workload represents a worst-case scenario of how long the notebook would last if it was taxed to the maximum.
Results analysis
As some of you may recall from an earlier article, the VivoBook S14 managed 5.5 hours in the old battery test benchmark. It’s quite a long way off from its claimed battery life of 24 hours but that’s because, as I mentioned earlier, the old battery test benchmark was intensive.
Looking at the numbers here using PCMark 10’s new battery test benchmark, the numbers are more encouraging and arguably more meaningful. In normal day to day use, the VivoBook S14 racked up over 12 hours; whereas when used solely for watching videos, it managed over 16 hours. That said, if you were to tax it heavily, it would run flat in just over two hours.
The Spectre X360 fared well too, lasting over 8 hours in both Modern Office and Video workloads. But quite worryingly, if you were to game on it or tax it really heavily, it would barely last 1.5 hours.
The gram 14 performed well too. Though it didn't last as long as the VivoBook S14, it managed over 11 hours on both the Modern Office and Video workloads. And on the Gaming workload, it lasted the longest at just over two and a half hours.
Considering that all three notebooks are powered by the new Intel Core i7-8565U processor, it wasn't surprising to see that all three recorded very comparable power consumption figures. During low intensity workloads, all three notebooks hovered around the 6W mark. During the intensive Gaming workload, however, the gram 14's power consumption was slightly lower at 28W whereas the VivoBook S14 and Spectre X360 bought consumed over 30W of power.
Final Thoughts
Notebooks these days have pretty impressive battery life. Some, like the ASUS VivoBook S14, has a claimed battery life of 24 hours! (Image source: ASUS)
One thing this little test showed is that modern ultraportable notebooks have pretty good battery lives. Granted, the VivoBook S14 and gram 14 both have large 72Wh batteries which are the exception rather than the norm, but even the Spectre X360 managed well over 8 hours in productivity and video-watching workloads and that’s with a power-draining touchscreen display set to 100% brightness, no less. Certainly, processor and other optimizations over the past few years have come a long way.
On the flip side, the intensive Gaming workload also showed that battery life can take a severe dip if the processor was to be heavily taxed. With that in mind, if you are working on battery power, it is essential to pay attention to rogue applications (using Task Manager) that might have encountered issues and are unnecessarily taxing the processor.
To end, going forward, we will be using PCMark 10's Modern Office and Gaming scenarios for battery life reporting. This will give readers a good idea of how much battery life one can expect in normal balanced usage and in the worst case scenario. Video is excluded since the results gathered are quite similar to that of Modern Office. Moreover, most manufacturers quote battery lives using video tests anyway.
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