It looks like the Galaxy S8+ was able to beat the battery life of the iPhone 7 in an extensive battery life test by Phone Arena. The Galaxy S8+ was able to last 8 hours while the iPhone 7 died after 7 hours and 46 minutes. When you consider the difference in battery size the feat doesn't seem to be that big of a deal. The iPhone 7 houses a 1960mah battery while the Galaxy S8+ features a 3500mah battery. The S8+ was not able to beat the iPhone 7 plus in the same test. The iPhone 7 Plus was able to last 9 hours and 5 minutes.
Phone Arena also found that the Samsung Galaxy S8+ lasts about an hour longer than the Galaxy S7 Edge which features a slightly larger battery. The 10nm chip seems to be much more efficient than last years models. In all the S8+ out performed other Android devices like the Google Pixel XL, OnePlus 3T, and Huawei P10.
via PhoneArena