Dell XPS 13 Ultrabook Review

Battery Life Testing

Let's face it, if you're shopping for an Ultrabook, you're less concerned with gaming performance and more interested in what kind of battery life you can squeeze out of these featherweight systems. This is perhaps one of the most important metrics, at least for some, and what we have below are examples of worst case and best case scenarios under light and heavy workloads.

Battery Eater Pro Stress Test
Light and Heavy Workloads

The results below are from our combined Battery Eater Pro (worst case) and Web Browsing only (almost best case) tests.  BEP beats on the CPU, GPU, disk and memory while it renders a 3D image and rotates it in real time on the screen.  Our light duty, web browser test refreshes a web page of mixed text, graphics, HTML and Flash, every 3 minutes.  Both tests are run with display brightness set to 50% with no sleep timers. All other power plan options are left as delivered from the manufacturer.  Please note we currently only have two ultrabook datapoints listed here for the web browser only test.

As you can see, the XPS 13 really sips power under light workloads in the web browsing test, besting the 12-inch Zenbook by a wide margin.  However, it also loses by a fairly significant margin under worst case conditions with Battery Eater Pro. For reference, the Asus Zenbook U21 has a 35Whr battery, while the Dell XPS 13 has a 47Whr battery built in.

Regardless, it appears that Dell more aggressively Turbos up the CPU under workloads but also has Windows power plan settings configured to dial things back hard when idle or with light loads.   This would explain why the XPS 13, with a slightly slower CPU than the Zenbook, beat all others by a small margin in our performance benchmarks, but also has the worst battery life under load and the best battery life so far when idle or under light loads (just browsing the web). 

In short, this probably is what most end users would want.  The XPS 13 cranks up quick to crunch workloads on demand but then pulls way back down when idle or when workloads are light, in order to maximize battery life. 

Incidentally, we looped a 1080p H.264 video clip continuously on a full charge and the XPS 13 lasted 4 hours almost to the minute, again at 50% display brightness.  Not bad at all.

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