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Altimeter Discussion

Former Member
Former Member
I have owned a Garmin 935 from almost when they 1st came out. Before the 935 I have a Fenix 3 HR, before that a Garmin 920XT and others before.

I really want to like the the 935, I love the size and weight of it, the battery life, the fit, the operating system and I like the idea of what its meant to do - I say idea of what its meant to do because I find it horribly unreliable. I have a spoken to Garmin support many times and I have even been sent a replacement watch and I have always been on top of updates, but I have no resided the fact that the watch is not very good by design.

Like everyone else I have massive problems with the Altimeter, every activity I record that is on land I get inaccurate information about altitude. My Altitude may start out correctly (I will often re-calibrate before an activity as its reading wrong), but the activity will always end with -36 or something like that. Why or why Garmin can my watch only use the Altimeter for Altitude? Your cheaper watches use GPS and I have found this far more accurate (my GF's watches she has had).

9 out of 10 sea swims I will get poor GPS data from, its usually very erratic, it usually looks like its only recorded half the distance or just draws dead straight or erratic lines. I have tried all satellite combinations but no luck. Sea swimming is probably the biggest failure of the watch. My GF's cheaper 735XT usually has no problems with sea swims.

Any running or cycling activities that might be over 4 hours - there will be a high chance of GPS failures here. GPS may drop signal for 5 - 10 minutes for no reason, in broad day light with no hills or trees in sight. I have also seen my GPS say i'm riding 100kms per hour when i'm stood still. Once again I have not seen these issues on my GFs 735XT. I have tried many different settings and satellite combinations but no good.

I have a few friends that own this watch but they don't see any issues, but they use their 935's for running and usually nothing longer than a couple hours.

So why dont I switch to a 735 you ask? Well I need the long capacity of the battery as many of my activities are long distance.

What do other people use and do that may have the same issues as me? Do you recommend other watches and what watches? The Fenix 3HR I felt too big on my wrist and caused me a bit of pain on my skinny wrists. I have heard the Fenix 5 has problems too, I dont know anything about the Fenix 5 Plus except its very expensive.
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    TMK17 do i have to do that before each workout or is it going to remember my elevation from now on ? I guess if i have my feet in the water, i should be at 0 elevation.
  • Former Member
    0 Former Member
    Pierrotsc You should always calibrate both prior to every workout. That being said, if you calibrate and then save that spot under saved locations, the next time you start an activity at that location, the watch will "remember" the saved data.
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    What I can already see is that just by removing my watch from the wrist and putting on a table for 5 minutes change the "ambiant pressure" from +2 hpa and so change the altitude for approximately -20 m.

    You would not be the first to see this with a 935 or a Fenix 5.

    I have tested quite thoroughly with my Fenix 3. On that watch, the ambient pressure measurement would only change by a few tenths of a millibar when I took it off my wrist and placed it outdoor at less than 10°C and let it cool down for 15 minutes.

    I now have a Fenix 5X+, and I have only tested it briefly in the summer where I could not create a very large temperature difference, but it also seemed quite insensitive to temperature. We have 3°C outside right now, so I ought to test it again.
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    TMK17 Ok i get it. Now if i am at the beach, and i go under the altimeter widget, do i set the elevation to zero or should i let the watch auto calibrate to see if it picks up the right elevation ? I do not want to mess up something. Thanks
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    I've been having altimeter issues for as long as I can remember. Not really sure which firmware first introduced it, but I waited a while to upgrade to 12.1, fearing it might make things worse. I should not have waited. Altimeter issues have disappeared for me on 12.1. Are there other, currently unknown issues introduced by 12.1? Probably. But at least my altimeter is working as expected again. I have auto-updates off, and don't plan on upgrading firmwares again for a while. Garmin has lost my trust in that department.
  • Former Member
    0 Former Member
    Pierrotsc GPS can have errors up to + or - 400 feet. I use my phone to find the elevation and barometric pressure, then manually calibrate.
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    TMK17 thank you. any free app you recommend ? i am on Ios.
  • Former Member
    0 Former Member
    Any weather website should be able to give you your current barometric pressure. I use to use the website www.distancesto.com for elevation, but now I use the widget "Elevation Widget" by r.485 which works great. It will find your location with GPS, but then it gives you your elevation based on geographical surveys from that location. This way you don't need an address like the website requires.
  • Former Member
    0 Former Member
    TMK17 Ok i get it. Now if i am at the beach, and i go under the altimeter widget, do i set the elevation to zero or should i let the watch auto calibrate to see if it picks up the right elevation ? I do not want to mess up something. Thanks


    No, You don't have to calibrate the Altitude before using the device for an activity - Go to your altimeter setting and make sure "auto cal is ON". Then every time you start an activity with GPS it sets the altitude for you. :)

    you only need to calibrate when your not really using GPS and the altitude is incorrect.

    Thanks

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    whitty_77 this is on how it is setup but the manual says that doing that may not be correct and you can have up to 400 feet difference. That is why you have to enter your known altimeter value I think. The elevation difference is fine during my bike ride but i am under water when i strat and finish from what the GPS is getting :)