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Altimeter issue

Leew72
over 6 years ago
Anyone else getting false elevation reading on the 645M ?? Mine is consistently overestimating by 600ft.. any way of calibrating this???
  • 0 over 5 years ago
    Have you contacted Garmin Support with the data?


    I have just e-mailed the above comment to Garmin Support.
  • 0 over 5 years ago
    I have just e-mailed the above comment to Garmin Support.


    Great! Hope they rectify it in another software update. On the replacement device and have another 20 days to return if they don't.
  • 0 over 5 years ago
    Great! Hope they rectify it in another software update. On the replacement device and have another 20 days to return if they don't.


    Seems like more of a software glitch to me so I’m not sure what use a replacement will be.
  • 0 over 5 years ago
    Seems like more of a software glitch to me so I’m not sure what use a replacement will be.


    My replacement was for other reasons. The software was very unstable on the first one and very choppy. Did everything Garmin Support asked but nothing worked. They sent me a new one once they determined the issue was with the watch itself.
  • 0 over 5 years ago
    Don't upgrade to firmware v4.0 (from v3.7). The elevation gain issue has regressed...



    Having the same issue with v4.0. I have a one week old FR645M, and I went for a ride today, recording the ride activity with both the new watch and my trusty Edge 820. Elevation profile recorded by the FR645M is totally smoothed out if you compare to the results from the Edge device. Over the course of an easy 21 mile ride, the FR645M reports 449 feet of elevation gain, where the Edge comes up with 794 feet of climbing. Screenshots of the two charts attached.

    ciq.forums.garmin.com/.../1418874.png
  • 0 over 5 years ago
    Unsurprisingly I've got stupidly over smoothed here too, attached is runalyze's elevation correction plotted against the original elevations from my 645. I certainly don't know that the runalyze version is correct but it sure seems to be a closer match. For instance while the small hill at 34 minutes was small it definitely did exist, and I very much remember cursing after that dip at the top of the big one fooled me into thinking it was downhill time. Then the gradual uphill starting around 1:02 doesn't show up on the 645's data at all either. Weirdly it doesn't look to have lagged much on the start of the first big hill at ~13:00 it's like it gets stupider as time progresses.ciq.forums.garmin.com/.../1418906.png
  • 0 over 5 years ago
    Don't upgrade to firmware v4.0 (from v3.7). The elevation gain issue has regressed...


    v4.10 still hasn’t fixed this. Any way to go back to a previous firmware?
  • 0 over 5 years ago
    Hello, i had the same issue comparing my old vivoactiveHr with my Etrex30, on an average 1000m ascend MTB tour it loses about 50m, and now in lesser way with my 645.
    II think it's related to a different sampling rate of barometric altimeter, wich trend to lose small ascends.
    I also assume that could be voluntary to prevent unwanted ascends caused by moving your arm up and down during running, my Etrex30 even counts if I lift it from the floor to my bike handlebar and then again down, don't want to think if it was on my wrist...

    Or is this bu*****t?
  • 0 over 5 years ago
    v4.10 still hasn’t fixed this. Any way to go back to a previous firmware?


    Elevation profiles for a 25km mountain bike ride attached. 523vm vs 269vm.ciq.forums.garmin.com/.../1424247.png
  • 0 over 5 years ago
    Ironically, I see the opposite with my 645.

    After upgrading from a VAHR, the altitude graph of my 645 look much noisier, adding extra feet to elevation gains. I mean, there's no a lot of real-world roads with 1-2 meter high bumps all over the place. So, I would actually prefer more smoothing of high-frequency/low-amplitude details.