GoPro is notorious for having terrible battery life in general. You are much better off bringing extra batteries so you don't have to worry about having enough time to film what you want to film.
YUP!!! Even with the battbac on my GP Hero I, & turning it off @ the bottom between recording, (...this is on SE MI. 90 sec.-3min. downhill bunny run blues & blacks BTW!) I needed 2-3 extra batteries to get thru the day! Need another 2-3 to get my Hero II thru a day!!!
I know, I KNOW!!! What a "Gapper" & Why bother with a GP, let alone 2 on this shit??? Gimme a break, I'm a NooB & didn't know any better!! (...besides, nobody I know would have believed I was doing as well as I was without Proof
...Aww who am I kidding?? I just like looking' at myself!!!!