Altimeter Fenix 5

Add me to the list. 1st F5 lasted less than a couple months before going wonky. Warranty. 2nd lasted less than a month. Warranty. They're sending me a free upgrade to a 5x, hopefully it's not too huge. They tell me the 5x is less problematic. When I bought my 1st, I also got a 5S for the wife. Hers has been working great.

Mines gone back and ive had a full refund .. in thecend i got the altimeter stable via calibration so was happy..then the auto pause function just didnt pick up that id moved off again so lost that distance and added a straight line if it did pick up again..sometimes a mile further on...clear skys no buildings.

then after fw8 the floors climbed dissapeared...that didnt bother me as im not interested in that but what did bother me was that a function just dissapeared after a so called up date...next time maybe it might be a function i am interested in.

just cant be bothered with it..


shame as i really liked the watch and really wanted to keep it so im very dissapointed ..spent months deciding on this device but £500 is a lot of money for me so it was a big purchase


maybe fenix 6 will be the fix...

New Fenix 5 user here, got it 2 days ago.

On my first run (which was at sea level) I had an altitude of about 50 meters. That was before calibration. I calibrated using the GPS and it was showing correct values until this morning. It's not showing crazy numbers, but it's still about 20 meters off. How accurate is it supposed to be? Maybe a few meters in nothing to worry about, or is it supposed to be VERY precise? I turned Elevation Correction on for now..

Correct altitude: 250 m
My fenix 5 shows between 8000 and 19000 (!) meters. It´s only correct after GPS-calibrating - for nearly 1 day ...:mad:

New Fenix 5 user here, got it 2 days ago.

On my first run (which was at sea level) I had an altitude of about 50 meters. That was before calibration. I calibrated using the GPS and it was showing correct values until this morning. It's not showing crazy numbers, but it's still about 20 meters off. How accurate is it supposed to be? Maybe a few meters in nothing to worry about, or is it supposed to be VERY precise? I turned Elevation Correction on for now..

The watch uses a barometric altimeter which senses the ambient air pressure and converts it to an altitude. This type of altimeter depends on knowing the present reference air pressure at a certain altitude, so it can calculate the actual altitude from the difference between the reference pressure and the measured ambient pressure. The watch gets this extra piece of information when you calibrate the altimeter.

However, the pressure at a given altitude changes all the time, often by up to 1 millibar/hour.

1 millibar of pressure change is equal to 8-9 meter of altitude change. So the altimeter can easily build up an error of 8 meter per hour. (The watch has some ways of handling this, so you will usually not see the full variation. But you will see some variation, depending on how good the watch was at guessing the reason for the pressure changes.)

In short: Your overnight 20 meter is nothing. It could be much worse. And it is not caused by erroneous measurement. It is caused by outside factors changing.

The watch uses a barometric altimeter which senses the ambient air pressure and converts it to an altitude. This type of altimeter depends on knowing the present reference air pressure at a certain altitude, so it can calculate the actual altitude from the difference between the reference pressure and the measured ambient pressure. The watch gets this extra piece of information when you calibrate the altimeter.

However, the pressure at a given altitude changes all the time, often by up to 1 millibar/hour.

1 millibar of pressure change is equal to 8-9 meter of altitude change. So the altimeter can easily build up an error of 8 meter per hour. (The watch has some ways of handling this, so you will usually not see the full variation. But you will see some variation, depending on how good the watch was at guessing the reason for the pressure changes.)

In short: Your overnight 20 meter is nothing. It could be much worse. And it is not caused by erroneous measurement. It is caused by outside factors changing.

Thank you for replying. For now I am testing manual calibration, see how that works. I found the altimeter of my job place online which is 6 meters. Will manually re-calibrate once I go for a run at sea level. i wonder how often I should be calibrating.

Are there any "optimal" altimeter settings or should i just leave everything on auto?

Are there any "optimal" altimeter settings or should i just leave everything on auto?

In my opinion, the non-auto modes are for some very special cases.

For example, if you are at sea, so you are always at the same altitude, it makes sense to force the watch into Barometer Mode, where it will assume that all changes in ambient pressure are caused by changes in barometric pressure at sea level, not by you moving to another altitude.

More altimeter issues...

On my 2nd Fenix 5 and second outdoor run for the watch. First run was yesterday and all seemed ok. Did a 20 mile run this morning and had a good GPS lock before the run. Never looked at altimeter before or during the run. Altimeter was in Auto calibrate, barometer watch mode was in Auto. When I got back from my run the elevation was grossly off - starting at 5000 feet versus 500. I’ve included screen shots of the elevation data from Garmin Connect both without and with elevation correction enabled.

At home I went through several calibrations for both altimeter and barometer. I then put it in Barometer for the watch mode (to lock the altimeter), and calibrated the Barometer again to that shown on the local weather site at 30.21”. After about 30 minutes, the Barometer has increased to 30.70”.

My my first Fenix 5 never had any issues. Elevation data on my runs always looked ok and I never messed with calibrations of the altimeter or barometer.

Questions:

With everything in Auto, isn’t the altimeter supposed to calibrate before the activity start? Shouldn’t my track had started a lot closer to my actual elevation of 500’? I understand that this is based on GPS data but there shouldn’t be that much of a discrepancy.

I’m assuming a 0.5 inch Barometer increase is way too much? The local weather site now shows 30.20 instead of 30.21. It’s a clear sunny day today.
ciq.forums.garmin.com/.../1329249.jpg

With everything in Auto, isn’t the altimeter supposed to calibrate before the activity start? Shouldn’t my track had started a lot closer to my actual elevation of 500’?

As I have said a lot of times in these forums: If you want to get to the bottom of what happens, you need to look at your ambient pressure measurement.

The altitude and barometric pressure are both derived values from the measured ambient pressure. If you try to troubleshoot by looking at the altitude, you are making "indirect" troubleshooting which is much harder.

My guess is that your measured ambient pressure was very, very low. Much lower than the real ambient pressure at your location. (Which could be caused by the well-known issue with static electricity from clothing creating errors in the ambient pressure measurement).

When you calibrate the altimeter (or it calibrates itself) from a known altitude, the watch will use the measured ambient pressure and the known altitude to calculate what the ambient pressure would be at sea level right now. This calculated value is also shown in the watch as "Barometric Pressure".

Now, if the measured ambient pressure was much too low, the calculated pressure at sea level will also be much too low - also much lower than the lowest pressure ever measured at sea level. Since I have never seen this error myself, I don't know what will happen in this situation. But it is very likely that the watch has a lower limit for the calculation of pressure at sea level, so it can't store the calculated value without correction. Then, when the altimeter later measures your altitude by comparing the actual ambient pressure to the stored pressure at sea level, it will compare to a wrong reference, and you will get a wrong result.

But all this is easier figured out if you look at the ambient pressure measurement of the watch. You can do that by enabling the Ambient Pressure data field in a data screen inside the activity you are using.

But all this is easier figured out if you look at the ambient pressure measurement of the watch. You can do that by enabling the Ambient Pressure data field in a data screen inside the activity you are using.

Thanks for the input. Set up a page to display elevation, gps elevation, ambient and barometric pressure. So here is what what I get:

1) When the activity is selected, 698 ft for elevation, 698 ft for GPS elevation, 28.03 for ambient pressure, 30.98 for barometric pressure.
2) When I select start, elevation changed to 1074, barometric pressure changes to 30.57, ambient presssure remains the same (expected), gps elevation slight change to 696.

Based on this website (https://www.mide.com/pages/air-pressure-at-altitude-calculator), and my actual elevation of 700’, weather barometric report of 30.13 and 48 degrees, I should be at an ambient pressure of 29.46 (assuming google did the right conversions to psi).

So does a difference of 28.03 vs 29.46 means a bad sensor? I will look at it over the next few days, but guess I’ll end up calling Garmin. As I said before, my previous Fenix 5 elevation was never an issues on any of my runs and never had to look at any pressure readings. A difference of 374 feet is much more than my old 620 would give just using GPS data.