Go Pro Hero 4 Batterie Life
 

How long does the batterie last on the Go Pro Hero 4 if you run it the whole time when recording video

With mine, ive noticed it can go up to 2 hours, maybe 3 if i don't do lengthy videos and keep them far and few in between. I may have to consider buying a battery pack booster.

It depends on several factors:
What brand of batteries? OEM are probably better than any of the replacements.
How old are the batteries? Recharging can take a toll after a while.
Are you using the LED lights and WiFi?
I have not tested it, but I would guess there is some loss in record time by using the higher resolutions and frames per second. (lots more info to be written).

I can tell you that I get about 1hr and 15 minutes of record time on new GoPro batteries. I am not using the WiFi and have the flashing LED lights off. The bad news is that the GoPro 5 - 7 get no better record time.