[js2]

It's really only been the last few years that running watches could last >24 hours with GPS tracking enabled.

I also have a Forerunner 935 which I've used for 24 hours, but I think I had it in ultra-mode where it takes GPS samples less often.

Before that I had a Forerunner 230 and I had to charge that mid race during a 100-miler, which was fun to do while running (used an external battery, put the watch and battery in a running vest while running one of my laps).

The latest watches which do 36 hours or more with full GPS accuracy are really amazing.