Results: Battery And Throttling
Basemark OS II Full (Anti-Detection)
The Basemark OS II battery test scores are derived by repeatedly running the devices until enough data has been collected to determine the drain rate of the device.
In our first battery benchmark, the Galaxy S5 turns in an average performance, sitting between the One (M8) and Xperia Z3, both of which have similar size screens and the same HD resolution. Despite having about an 8%-larger battery than the HTC, Samsung's S5 scores 10% lower. However, it performs better than the 11%-larger battery in the Xperia Z3 by about the same amount. The iPhone 6 has a substantially smaller battery than the S5 (1800mAh versus 2800mAh), but manages to perform slightly better, its smaller screen, efficient SoC and software optimizations helping to reduce power drain.
GFXBench 3.0 Corporate
GFXBench's battery test measures battery life and performance stability by logging frame and battery discharge rate as the on-screen T-Rex test runs for 30 consecutive iterations. The results are given in two scores: estimated battery life in minutes and the number of frames rendered on the slowest test run (to gauge if a device is throttling).
This test stresses the GPU and serves as an indicator for battery life when playing games. With its chart-topping performance, one might conclude that the S5 is a clear winner. However, this chart doesn't tell the whole story. We also need to look at the average frames per second during each run to see how much work the phones are actually doing. Noting that the two all-metal phones have the worst battery life here foretells what we'll see in the next chart.
Average performance for the S5 over thirty iterations of T-Rex drops to 18 FPS compared to 27 FPS for a single iteration, indicating thermal throttling. The three metal phones—iPhone 6, One (M8) and OnePlus One (internal magnesium chassis)—are able to dissipate heat more effectively, which means they continue to operate at peak frequency and consume more power.
The diagram below shows how the S5’s performance varies over time.
While not as severe as the thermal throttling we saw with the LG G3, the S5 still can't keep its GPU running at 100% for long before it has to throttle clock rate.
Battery life for the Galaxy S5 is merely average. Unfortunately, the upcoming update to Android 5.0 will likely reduce battery life further, since AMOLED screens are most efficient with dark interfaces (effectively no power draw when displaying black) and Lollipop uses all-white backgrounds.