Apple Watch for Ultra Running?

I want to use my Apple Watch to track my runs and races of longer time and distance.  I don’t know if the battery will last…

I do like wearing my watch on a day by day basis.  It works for unlocking my Mac, quick checking message’s, telling Siri what to do, etc.  I want to be a one watch guy, so even though I tease myself with Instagram streams of mechanical watches, I’m not sure if I would ever wear a mechanical for work and change to a workout watch for working out…  I really do want one watch to rule them all.

The problem is that the battery doesn’t last long enough in a workout.  4-5 hours tops.  I’ve already killed the battery this year at Spartan World Championships at Tahoe.  It was a long day…

The best advice I can find online about making the Apple Watch battery last longer in a workout is to use a HR chest strap.  Apparently the HR feature is the battery killer, even more than the GPS running.

I tried saving the battery at the Spartan SoCal #2 Best by wearing a HR chest strap, but the strap got in the way of the obstacles and kept getting undone.  So, for OCR at least, that didn’t work.

I have a 50k and a Spartan Ultra Beast coming up next year.  I’ve got time to figure this out, but there may not be a solution.  Other than buying a Garmin and putting up with their un-readable screens….