The first-gen Blade Stealth disappointed on the battery life department. The 45 Wh battery was smaller than the average 13-inch notebook, and battery life sat much lower than competing ultrabooks. In fact, the amount of life provided by the original Blade Stealth was no better than a gaming laptop.
With the new Blade Stealth, Razer has increased the battery capacity to 53.6 Wh. Considering this battery is just under 20% larger than its predecessor, when combined with Kaby Lake's slightly improved efficiency in low power SKUs, the new Blade Stealth should last a fair bit longer. Razer themselves list "up to 9 hours" of battery life.
In both our laptop battery benchmarks, the Kaby Lake Blade Stealth significantly outperforms its Skylake predecessor. The new Blade Stealth is competitive with other ultrabooks like the Dell XPS 13, Surface Book, and Asus ZenBook 3, which is what I wanted to see.