In the following benchmarks we employ two very different battery life tests: Battery Eater Pro and a custom 1080p HD video loop test, to prove out battery life with our test group of machines and the Razer Blade Stealth. In all tests, Windows 10 Quiet Hours have been enabled and displays are calibrated with lux meters on pure white screens to 115 lux. For the average notebook this is somewhere between a 45 - 60% brightness setting. Since notebook displays significantly affect power consumption and battery life, it's important to ensure a level play field with respect to brightness of the display for battery testing. However, since many notebook displays vary in brightness at each respective brightness setting in Windows, this calibration with the meter is also critical to ensure all displays are set to as near identical brightness as possible before testing.
Battery Eater Pro
Battery Eater Pro wears systems down quickly with a heavy load on all subsystems, including processor, graphics, memory and even storage. This is truly a worst-case test that will give you a sense of how a machine will hold up under heavy strain, when gaming or under heavy-duty continuous content creation workloads, for example.
HotHardware Video Loop
Our custom HotHardware video loop test takes a 1080p HD video with a 16Kbps bit rate and loops it repeatedly, with 1 minute break intervals in between. A timer log file increments minutes of uptime every minute and a final minutes total recorded before system shutdown is stored in the log. This is a lighter duty test that is still a bit more strenuous than say many office productivity tasks but it's not nearly the strain that Battery Eater puts on a system.
This is the part of the review Razer probably hopes you will skip over. The Razer Blade Stealth already packs a smaller battery than the competition at just 45Wh. That's about a 20% reduction compared to Dell XPS 13's, ThinkPad Yoga X1's, and HP Spectre X360's 56Wh batteries. The battery life is further impacted by the Stealth's tendency to keep its fans running even while idle, though at least they are rather quiet. The cold truth is that the Blade Stealth simply won't last as long as its competition. 4 hours is still a decent enough runtime though, so it can get you through a couple classes or meetings with ease, as long as you don't need it to go all day.