I recently did some window-sill tests with my Fenix 3 + iPhone5s-garmin-connect with live-track turned on. The idea was to see the battery impact of tracking for many hours. In these home tests (with ultratrak turned on on the watch), I could leave things tracking for 9 or so hours and only have a 20%-30% impact on battery life on both devices. So I assumed I'd be ok to run a 100 mile ultra - with the phone and watch lasting at least 25-30 hours.
This last weekend I set off to run that ultra, but the phone ran out of battery after only 14 hours.
The only cause I can think of is that the trail goes through a lot of areas with little phone coverage - so perhaps the GC mobile app was using trying too hard to send my live tracking information on very weak signals, instead of waiting until signal strength got a bit better.
Anyone else experienced this? Anyone know of alternative live-tracking solutions that don't burn battery in these circumstances?
Note that on the good side, the Fenix 3's battery lasted very easily through the whole event.