Coming straight from Samsung's homeland, an impromptu battery test reveals that the Galaxy S5 is shaping up to be quite the endurance champ. The flagship is laden with a 2800 mAh battery, while we have phones in the same category with 3000+ mAh units, like the Xperia Z2.
Capacity is not everything, but given today's largely uniform components, it is a pretty good determinant of the overall endurance. Unless you mounted a display with older technology, that is (cough, Z1, cough), which would draw quite a lot of power, resulting in unimpressive screen-on times even with a 3000 mAh unit in there.
Still, as you can see from the charts below, the Galaxy S5 topped the available phone row, and sits just below popular tablets and phablets, whose batteries are much larger. The screens were set at roughly 230 nits of brightness, as well as in peak luminance mode, so the Wi-Fi browsing test has been quite tasking, and yet the S5 managed to pull off more than 7 hours of screen-on time, which is quite impressive. We'll put the Galaxy S5 to the battery test ourselves soon, but in the meantime it seems that battery life won't be an issue with the handset.
Prompted by a reader comment, we are inserting another battery life test chart, which confirm the stellar endurance of the S5. There the phone lasted more than 10 hours of browsing via Wi-Fi, which is in line with what Samsung promised. This test, however, has been done with the screen set at just 120 nits of brightness, that is why the battery life stats are much higher than in the first scenario, where the screen is set at 230 nits or more.