Battery life is a very interesting case for the Galaxy S8+. We're looking at a 3,500 mAh (13.48 Wh) cell, which is a slight decrease on the 3,600 mAh battery we saw in the Galaxy S7 Edge. We're also seeing a larger display, which typically reduces battery life, though a more efficient SoC process technology. So there are a range of factors impacting battery life.
The Galaxy S7 Edge had fantastic battery life, and it's great to see the Galaxy S8+ largely living up the performance of its predecessor here. Interestingly, the S8+ lasts longer in more processor-heavy benchmarks, like PCMark and GFXBench, but it falls behind by a small margin in our web browsing tests.
The Galaxy S8+ performs well when compared to other current-generation flagships. It outperforms the Pixel XL by around 10 percent on average, though it falls behind the massive Huawei Mate 9 and its huge battery. I have some more phones to test in the coming weeks, so it'll be interesting to see how the S8+ performs up against new flagships from LG, HTC, Huawei and Xiaomi.
Note that these results do not consider the always-on Galaxy S8+ display. If you leave that feature enabled, you will experience higher standby battery drain than most other smartphones, which can lead to reduced overall battery life.