I was hoping to upgrade from my hero 3 black to a hero 5. Which one has a better battery life while using the self-timer?
Referring to GoPro's support pages for battery life:
- HERO3 Camera Battery-life
- HERO3+ Camera Battery-life
- HERO4 Camera Battery-life
- How Long Does the HERO5 Black Battery Last?
For the Hero 3 Black, GoPro states
Avg. time for lowest power consumption setting: 1.5 hrs (1080-30)
For the Hero 5 Black, GoPro states the "Estimated Time" for recording 1080p 30fps Wide (the closest recording mode to make a meaningful comparison to the Hero 3 Black's battery life),
Video Only: 2h 30m
Video + EIS + GPS: 2h 5m
Video + EIS + GPS + WiFi ON: 1h 45m
So, assuming "Estimate Time" (Hero 5 Black) is the same as "Average Time" (Hero 3 Black), when recording at 1080p 30fps, the Hero 5 Black should typically record longer than the Hero 3 Black did, even if image stabilization, GPS, and Wi-Fi are enabled on the Hero 5 Black.
Edited to address timelapse addendum to question
GoPro doesn't seem to address how long batteries will last while shooting timelapses, in their battery life support pages. However, several sources suggest that timelapses will suck down the battery at a similar rate to video recording, due to the fact that the GoPro doesn't turn itself off, or at least go into low-power mode, between shots.
From How to Shoot a Long Timelapse with a GoPro HERO4 Silver or Black at David Coleman's HaveCameraWillTravel.com photography blog:
The problem is that the camera doesn’t switch off between individual shots. A single shot is over in a fraction of a second, but GoPros stay on until the next shot. So it chews through battery power at a pretty constant rate shooting timelapse whether you’re using a timelapse interval of 1 second or 60 seconds. If you’re lucky, you might get about 2 hours out of the internal battery, perhaps less.
So assuming the relative battery life numbers between the Hero 3 Black and Hero 5 Black more or less apply when timelapsing, then based on the above statement from David Coleman's blog, the battery should not last substantially† longer for timelapses than it does for normal video.
† Personally, I would expect the battery to last at least somewhat longer. Video recording and encoding is somewhat intensive, as compared to not performing any calculations on the processor. Even with hardware-based encoding (more efficient than pure software-based encoders), even the lack of constant streaming to the MicroSD card should consume somewhat less power than when recording video.
See also the related question, How can I take an extended timelapse with my GoPro given the short battery life?