If you're planning on using your HERO3 camera for extended periods, get yourself a couple of these spare batteries. When recording as hi-res, or using with WiFi, they tend to chomp through batteries. Don't get caught out! Includes a handy little tab to make it easier to pull the battery out of your camera.
1180mAh lithium-ion rechargeable battery
Use as a spare or replacement battery for your GoPro camera
Also works for Hero3+