Power modes vs Ultratrac vs Expedition

Nice. I want to experiment with lower-rate GPS sampling but I think a sample every 15-30-60 seconds would be more ideal than every 15 minutes if there was still meaningful power savings to be had. Better if there was a way to do it without giving up GLONASS/GALILEO. The one time I used Ultratrac with an Instinct (in mountain terrain, but WIDE OPEN, great view of the sky), the GPS track was unusuably bad. I switched it mid-activity from GPS + GLONASS to Ultratrac and the points were jumping around by like kilometers - like you gave a toddler a map and a red crayon.

Since then I haven't even bothered to try it again.

Yeah, I wish we could drop the Expedition sample rate to as low as 1 minute, maybe adding 2-minute, 5-minute, 10-minute intervals.

It takes a while to get a lock and take a point in Expedition mode (10-seconds?) so I don't think you could go much lower than a minute without the GPS chip just being "on" all the time.

Even if a 1-minute sample cut battery life down from 37-days (5-weeks, 2-days) to 14-days or so, that'd still be more than triple Ultratrac's 4-days.

I wonder if it's a limitation of the Sony GPS chip firmware or a marketing decision by Garmin. Worth putting in a suggestion: https://www.garmin.com/en-US/forms/ideas/

Have you done any testing on Ultratrac accuracy? I'm searching the forums and finding people with terrible GPS plots e.g. this post from a 40km run in the UK that turned into 60km on the recording. Of course that's not with the new Sony GPS chip, so things may have changed for the better...

Fortunately I don't plan to be doing any activities the F6X battery can't handle if I turn off WHR and pulse ox - that was not the case with the Instinct which is why I returned it. Worst-case scenario would be multi-day activities with <20h of recording per day. An evening recharge would fix that, but there probably aren't too many more of those in my future. Glad I'm not an ultra runner.

EDIT: You would think that if the GPS chip is capable of getting a fix during open-water swimming when the watch briefly surfaces, there might be a way to get sporadic-but-accurate data points on a terrestrial activity. Maybe it wouldn't save any power though.

I haven't used Ultratrac or Expedition at all yet - this is all theory.

multiades said:

You would think that if the GPS chip is capable of getting a fix during open-water swimming when the watch briefly surfaces, there might be a way to get sporadic-but-accurate data points on a terrestrial activity.

I think swim and expedition would be two completely different power-modes for the Sony chip. In swim mode, it's already in high-power, full-on search mode with a lock from the start of the swim. In expedition mode, it's fully off most of the time.

Supporting that hypothesis is that swim was available on the Forerunner 935 and Fenix 5 with the Mediatek GPS chip but Expedition mode wasn't added until the 945/F6 with the Sony chip - it's likely a new power mode entirely.

Otto-Destruct said:

Supporting that hypothesis is that swim was available on the Forerunner 935 and Fenix 5 with the Mediatek GPS chip but Expedition mode wasn't added until the 945/F6 with the Sony chip - it's likely a new power mode entirely.

Which GPS chip does the Instinct use? It has Ultratrac (my previously posted picture) but it uses older hardware like the F5-era OHR...

I was referring to Expedition mode - it differs from Ultratrac.

Cool thread! I haven't yet got on any extended excursions with my Fenix yet, but when I do, this info will come in handy!

A runner in another thread also made a custom power mode where GPS gets turned off entirely - and he switches that power mode on whenever he stays in one spot for a while, so that he can save the battery without having to pause the activity.

One setting not mentioned there is setting a timeout for the display, which should squeeze you an extra few hours.

+8 hours, according to my 6X. Which is significanly more than you get from disabling the phone connection, which is only +2 hours.

Otto-Destruct said:

Yeah, I wish we could drop the Expedition sample rate to as low as 1 minute, maybe adding 2-minute, 5-minute, 10-minute intervals.

It takes a while to get a lock and take a point in Expedition mode (10-seconds?) so I don't think you could go much lower than a minute without the GPS chip just being "on" all the time.

Even if a 1-minute sample cut battery life down from 37-days (5-weeks, 2-days) to 14-days or so, that'd still be more than triple Ultratrac's 4-days.

I wonder if it's a limitation of the Sony GPS chip firmware or a marketing decision by Garmin. Worth putting in a suggestion: https://www.garmin.com/en-US/forms/ideas/

It's possible that the GPS chip uses significantly more power while acquiring a signal, than it does after getting a signal lock - which means that it's possible that setting the frequency to less than 15 minutes might actually cause the battery drain to be equal to or greater than just leaving the GPS on.