Battery Life
The OnePlus 2 comes with a non-removable lithium-polymer battery with a rated capacity of 12.54 Wh (3,300 mAh at 3.8V). This is larger than we've seen from other flagships like the Galaxy S6 (9.81 Wh; 2,550 mAh) and LG G4 (11.55 Wh; 3,000 mAh), including those like the G Flex 2 (11.4 Wh; 3,000 mAh) that also use Qualcomm's Snapdragon 810 SoC.
Throughout my time with the OnePlus 2, I observed battery life to be good without being great. The Snapdragon 810 is still a power-hungry SoC, and the large display does no favours when it comes to lengthy battery life. That said, the 12.5 Wh battery is large enough to compensate for these issues, delivering reasonable battery life that mostly lasted a full day.
As for charging, the OnePlus 2 lacks fast charging support, which is a disappointing omission considering many flagships these days support the feature. This handset isn't slow to charge by any means, but it will take significantly longer than devices like the Galaxy S6 or HTC One M9, especially when you're trying to boost its charge by 30-40%.