Altimeter Fenix 5

First, forget the actual temperature in your calculation of pressure. The weather service is probably using a standard temperature from the ISA atmospheric model, ignoring the actual temperature (and your watch probably does too). At your altitude, the standard temperature will be somewhere around 12 °C or 54 °F. But this will not affect the calculation much, so your results are still just about correct.

The difference between 28.03 and 29.46 is very large. There was a forum thread some months ago where users compared their watches to weather services and found that most were within 1-2 millibar. Your watch seems off by 50 millibar.

Anyway, what is probably most important is the relative reading of the pressure. Over the next days, look if it reliably follows the weather station up and down with a fixed error. If the error is constant, it may be easier to live with. But if you have variation in the error, the watch will become unusable for altitude measurement. And of course your experience from your earlier posted outdoor run indicates that the error is not constant. Also keep an eye on the ambient pressure if you go up and down stairs. If my conversion to your units is correct, you should see the ambient pressure drop with 0.01 inch Hg for every 10 feet your elevation increases.

Regarding the jump to 1074 feet. I guess this was an autocalibration where the watch pulled a known altitude that it had earlier stored at the same GPS location. Garmin watches do that, and it usually works quite well. But it also means that once they have gotten the altitude wrong at a location, they will continue using that wrong altitude, ignoring the GPS altitude. The remedy is to start a GPS activity, make sure you have green ring so there is a GPS fix, then with the activity still running go into settings and calibrate your altimeter to your known altitude. This way you have manually calibrated your altimeter while the GPS was running, so the watch knew your location. So the watch will store your location and altitude in the table of known locations and altitudes and use the correct altitude for autocalibration the next time you start an activity there.

Hi everyone I bought a f5 but I'm afraid of a damaged barometer sensor. Often in the morning just waking up, in auto mode, the altimeter start ti give impossible values, thousands and thousands of meters differences! Could please help me to understand if It is sftw bug or hardware?!?i have already made a susbitution via Amazon cause the dame reason...
thanks everyone in advance!

I'm now on my third Fenix 5. All have exhibited the "altimeter freak out" issue (i.e. wild "ascents" up to 64,000+ ft and descents 6,000+ feet below sea level).

Assuming that this is the problem that you're experiencing, then (as others have stated earlier) the problem is due to static electricity. I can consistently get my Altimeter readings to freak out after (or before) my bike rides and/or skiing by simply making sure that:

1) I'm in an exceedingly dry climate (I live in Colorado/USA, with only 20 to 25% humidity in the winter)
2) I'm exercising in a cold climate, thus the need to wear polyester based long-sleeve exercise clothing or jackets.
3) I build-up a really nice amount of static in my clothing/jacket before I take it off (given items 1 and 2 above, this happens without even thinking about it)
4) I take said clothing/jacket off while ensuring that the sleeve full of static drags across my watch.

Voila! My watch will have me climbing Mt. Everest within the hour and then descending below the Dead Sea shortly thereafter.

I strongly suspect that the reason that not all users are experiencing this issue is because of one or more of the following:

1) They aren't using their watch in a really dry climate
2) They aren't using their watch in really cold weather (i.e. no need for long-sleeve polyester), or
3) They have a version of the watch with a different bezel material and/or construction than that of the base Fenix 5 (stainless steel). (i.e. the different material and/or construction is not as conducive to conducting static as that of the base Fenix 5.

This also explains why the same users are having the same problem over and over regardless of how many warranty replacement watches they've went through (me included): Their base conditions have not changed.

The solution (until such time as Garmin is able to figure out how to protect the sensor from static):

1) Whenever possible, remember to take the watch off before you put on (and take off) long-sleeve polyester based clothing.
2) If you forget and/or otherwise trigger the "altimeter freak out" problem then (as others have said earlier) turn off the watch and put it in a bowl of very warm soapy water for a minimum of 30 minutes (and even longer if you can).

The warm soapy water solution has worked for me every single time across three (3) different watches. And now that I know what the problem is and how to avoid it, I have been going weeks between having to do the warm soapy water trick.

Hope this helps!



PS I too think it's ridiculous to spend $500+ on a watch only to have to use "warm soapy water" to get it to work correctly. That said, from my perspective everything else about the watch is so awesome (and I don't say that lightly) that I'm not willing to settle for a lesser watch because of this issue, substantial as it is. For now, I'm continuing to give Garmin the benefit of the doubt that they'll eventually figure out a fix for this problem and make it right for all of us.

Thanks a lot.I'm trying ti investigate if It is a possibile cause of the problem with my f5..but obviously it's notte Easy ti understand.howhever if this is one cause Garmin in my opinion should keep a clear position..but It seems like they are not so interested in solving the bug!
thanks a lot!

I coulden't agree more with thomjw. We also had low humidity and dry cold weather, my f5 went crazy on a daily basis Now humidity is back to normal, 50%, and the f5 is spot on again.

I cannot explain why, but for the last 2 months my altimeter behaves perfectly well. Before that I had to use soap bath at least once a week and I already replaced my watch in late November for the same issues (the new one showed altimeter crazy behaviour after only 2 weeks). I didn't change anything that could explain the fix (settings or apps). My altimeter is in Auto mode and I am using several watchfaces, some of them displaying altitude. Just noticed two things: no issue since v.8.0 firmware and weather was often very dry when I had issues (<50% RH).

I will look at it over the next few days, but guess I’ll end up calling Garmin.

Just an update..I tried to call Garmin and got impatient with an hour wait time, so during that time I just took it back and exchanged it for another one (watch was a week old). In my case I was pretty confident it was not a static electricity issue. I’ve been on the treadmill with the replacement until today, but since I got it earlier in the week altitude readings all seemed right. Today’s run looks very good (same clothes, probably 5 degrees colder than last weeks run). I’m sure you could nit pick some of the differences when compared to the corrected elevation data, but my issue was gross and inconsistent errors. With the ‘bad’ watch one run it did improve some over time, another it got steadily worse.

I’ve had a Garmin for years (going back to the 305) and to be honest elevation data would get corrected then (via Sporttracks) and just because the Fenix 5 records it with a barometer it doesn’t change how I train or track my runs. In fact having it corrected I’m sure makes it more accurate on the Fenix 5. But when you pay 650 for something you do expect all the features to work. Looks like the replacement does now.

I'm now on my third Fenix 5. All have exhibited the "altimeter freak out" issue (i.e. wild "ascents" up to 64,000+ ft and descents 6,000+ feet below sea level).

Assuming that this is the problem that you're experiencing, then (as others have stated earlier) the problem is due to static electricity. I can consistently get my Altimeter readings to freak out after (or before) my bike rides and/or skiing by simply making sure that:

1) I'm in an exceedingly dry climate (I live in Colorado/USA, with only 20 to 25% humidity in the winter)
2) I'm exercising in a cold climate, thus the need to wear polyester based long-sleeve exercise clothing or jackets.
3) I build-up a really nice amount of static in my clothing/jacket before I take it off (given items 1 and 2 above, this happens without even thinking about it)
4) I take said clothing/jacket off while ensuring that the sleeve full of static drags across my watch.

Voila! My watch will have me climbing Mt. Everest within the hour and then descending below the Dead Sea shortly thereafter.

I strongly suspect that the reason that not all users are experiencing this issue is because of one or more of the following:

1) They aren't using their watch in a really dry climate
2) They aren't using their watch in really cold weather (i.e. no need for long-sleeve polyester), or
3) They have a version of the watch with a different bezel material and/or construction than that of the base Fenix 5 (stainless steel). (i.e. the different material and/or construction is not as conducive to conducting static as that of the base Fenix 5.

This also explains why the same users are having the same problem over and over regardless of how many warranty replacement watches they've went through (me included): Their base conditions have not changed.

The solution (until such time as Garmin is able to figure out how to protect the sensor from static):

1) Whenever possible, remember to take the watch off before you put on (and take off) long-sleeve polyester based clothing.
2) If you forget and/or otherwise trigger the "altimeter freak out" problem then (as others have said earlier) turn off the watch and put it in a bowl of very warm soapy water for a minimum of 30 minutes (and even longer if you can).

The warm soapy water solution has worked for me every single time across three (3) different watches. And now that I know what the problem is and how to avoid it, I have been going weeks between having to do the warm soapy water trick.

Hope this helps!



PS I too think it's ridiculous to spend $500+ on a watch only to have to use "warm soapy water" to get it to work correctly. That said, from my perspective everything else about the watch is so awesome (and I don't say that lightly) that I'm not willing to settle for a lesser watch because of this issue, substantial as it is. For now, I'm continuing to give Garmin the benefit of the doubt that they'll eventually figure out a fix for this problem and make it right for all of us.

I agree completely with your assessment of static being the root cause! I can get mine to do it at will with the right clothing on.
It is static that causes the issue. There is a nice post earlier in the thread about the watch being a capacitor due to the metal top and bottom.
The only solution is the warm water and then drying and the altimeter will stabilize.

I have the 935 as well which has the same electronics but a composite body and it has been very stable with no fluctuation at all other than small drifts here and there from barometric changes.

Just wanted to add my name to the list of Fenix Altimeter Freak Out Victims Anonymous. My Fenix 5 is currently at Garmin for this reason and I'm using my Fenix 3 HR in the mean time which has zero problems.