Battery Life
As the Galaxy S6 and S6 Edge do not feature removable batteries, a feature Galaxy fans have enjoyed since the very first Galaxy S, battery life is more critical than ever before. Inside the Galaxy S6, Samsung has included a 9.81 Wh (2,550 mAh at 3.85 V) battery, while the Galaxy S6 Edge gets a slightly larger 10.0 Wh (2,600 mAh at 3.85 V) battery. I'm not quite sure why the Edge has a larger battery, though I suspect it could be down to slightly higher power requirements for the curved display.
Compared to the Galaxy S5, Samsung has decreased the battery capacity in the Galaxy S6 by 9%, and in the S6 Edge by 7%. The company is betting that a more efficient SoC, produced on a 14nm manufacturing node as opposed to 28nm, as well as improvements to display technology, will keep the battery life of the Galaxy S6 close to the Galaxy S5.
It's also worth mentioning that the Galaxy S6 includes a range of new charging options that, at least partially, help to offset the reduction in battery capacity. The vast majority of Galaxy S6 and Galaxy S6 Edge models come with both Qi and PMA wireless charging, which is very handy if you already own a wireless charging mat. Both devices also support fast charging, with Samsung vaguely stating you can get four hours of use from a 10 minute charge.
Let's see how the Galaxy S6 performs in our range of benchmarks
Starting with the web browsing benchmarks, the Galaxy S6 is a solid performer on Wi-Fi, falling within the top collection of smartphones. It lasted roughly 10% longer than the Snapdragon-powered Galaxy S5, which is a great result considering the smaller battery. On LTE, the Galaxy S6 is more of a mid-range performer, falling behind the Galaxy S5 by 13%.
While the Galaxy S6 does fall behind recent battery powerhouses like the Sony Xperia Z3, compared to other recent flagships it does quite well. Despite packing better performance, a smaller battery, and a higher resolution display than the HTC One M9, the Galaxy S6 lasts longer across the board. In my general usage, I thought the Galaxy S6 was pretty decent in terms of battery life, and noticeably better than devices like the One M9 and LG's G Flex 2.
The Galaxy S6 also does well in the more performance-oriented PCMark battery benchmark, again beating out a range of current flagships despite packing a smaller battery and higher performance. The Xperia Z3 still does very well here, though I hope someone attempts to dethrone it this year. GFXBench wasn't as good of a win for Samsung, but it still managed to edge out the HTC One M9.