Battery Life

The original Surface Book we tested was the Core i5 model, and it offered amazing battery life that the Core i7 model with a discrete GPU couldn’t quite match. With the Surface Book 2 15, the battery capacity has increased, although so has the display size and resolution, so it’ll be interesting to see how that impacts the results.

Our battery life tests include our older 2013 web browsing test, a newer 2016 web browsing test which is more demanding, and a movie playback test. All of our browsing is done with Edge, and movie playback with the built-in Films and TV software, with the display set at 200 nits of brightness.

2013 Light

Battery Life 2013 - Light

You feel kind of greedy when you feel like almost 14 hours of browsing isn’t enough, but it felt like the Surface Book 2 might really set a new record with the large 85 Wh of battery capacity. The new model handily outperforms the outgoing Surface Book Core i7 though, despite the larger display and higher resolution.

The tablet itself will still get several hours away from the base, which is more than enough time for the use case of the tablet, which is going to be for short sessions away from the base.

2016 Web

Battery Life 2016 - Web

Our newer web test is more demanding of the CPU, and on devices like the Surface Book 2, where the CPU power usage is a significant factor in the overall power drain, the result is less battery life than our older, easier test. At almost ten hours of battery life though, the Surface Book 2 still offers a lot of time off the mains.

Normalized Results

Battery Life 2013 - Light Normalized

Battery Life 2016 - Web - Normalized

By removing the battery capacity from the equation, we can see the efficiency of each device. Here, the larger battery size is removed, and the Surface Book 2 ends up about midfield. The larger display and higher resolution of the display are a significant impact on the battery life.

To dig in to this a bit more, additional testing was done to see just how much power the display draws. At maximum brightness, and with the system at idle, the display draws 7.65 W of power, while the rest of the system only consumes 1.43 W of power. On our 200 nit display brightness setting, that power requirement of the display drops to 4.1 W, which is still over double what the rest of the system is using at idle. The display is a significant factor, as expected.

Movie Playback

Battery Life Movie Playback

Battery Life Tesseract

When playing back a movie, the CPU can offload the task to fixed function hardware, so the overall power usage goes down even further than normal. The Surface Book 2 offers tremendous battery life at this task, coming in at close to 15 hours.

This would let you play The Avengers over six times on a single charge. That should be enough for almost any scenario.

With just the tablet, the battery life is still almost five hours of movie playback, which is certainly usable, although I doubt most people would use just the tablet to watch movies due to the size of it.

Charge Time

Despite the larger battery, the 100-Watt AC Adapter charges the battery quite quickly, and both batteries are full in under three hours.

Battery Charge Time

Both batteries charge at the same time, and are almost in lock-step with each other in terms of charge, despite the difference in capacity.

For those interested, the bottom of the tablet features the same Surface Connect port, so you can charge the tablet away from the base if necessary, although most of the time it would be charged when docked.

Display Analysis Wireless, Speakers, Thermals, and Accessories
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  • prophet001 - Thursday, December 21, 2017 - link

    If that 1060 isn't starved for cooling, I'll eat my hat.
  • denis.lafronde - Thursday, December 21, 2017 - link

    It's not, it's written in the review. So how's your hat? Taste good?
  • DanNeely - Thursday, December 21, 2017 - link

    The 1060 should be crushing the 1050 in the Dell XPS by 2:1. It does so in a few benchmarks; but falls short in enough (actually scoring less than the XPS in a few) that it's being bottlenecked by something badly in some cases.
  • skavi - Thursday, December 21, 2017 - link

    that's the CPU bottleneck. they're comparing the XPS 15's 45 watt CPU to the Book's 15 watt one.
  • Brett Howse - Thursday, December 21, 2017 - link

    As Skavi said this is the CPU bottleneck compared to the i7-7700HQ. Only falls short on tests where the settings are low enough that the GPU is no longer the bottleneck.
  • tyaty1 - Thursday, December 21, 2017 - link

    It starves badly. When the GPU usage is high enough, the GPU performance drops below of the 1050's because of thermal throttling.
  • tipoo - Thursday, December 21, 2017 - link

    Where was this? I saw one nearly horizontal GPU clock bar
  • skavi - Thursday, December 21, 2017 - link

    I'm not sure tyaty1 read the same review.
  • Brett Howse - Thursday, December 21, 2017 - link

    You've got it backwards. It falls below the 1050 only when the CPU is the limiting factor because the game settings are low enough that the GPU is no longer the bottleneck and the i7-7700HQ outperforms the 15W CPU in the SB2. It's not a power issue.
  • prophet001 - Thursday, December 21, 2017 - link

    Well it's power starving so it doesn't thermally starve. I make my hats out of chocolate so they taste pretty good.

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