My wife's 645M was supposed to be an upgrade from the Vivoactive HR. However, her first run today got the altitude so wrong it's not fit for purpose. The run started at +20 feet above see level, from a position in the street away from the house. the run was relatively flat, with no more than about a 30ft min/max elevation. The 645M recorded the had the elevation between min/max at 25ft, which I'd guess is somewhere near correct, but the lowest point was recorded as -226ft. which is an error of -246ft and is obviously unacceptable. When the GPS locks and grabs the altitude it should be no less accurate than around +/- 80 - 100ft, and that's based on GPS satellites on a bad day! The Vivoactive HR was pretty accurate with usually only 10ft errors or so. However, it also appears to have produced bigger (nowhere near that of the 645M though) altitude errors since the second half of December. Has there been an update since the middle of December? Does anyone else know of any current issues with the latest firmware or the 645M watch?
I took my replacement watch out for a run this morning, a path along a river so pancake flat. Sad to say it was exactly the same behaviour with a sawtooth elevation graph. Think I'm going to give up on this one as guessing it's a design flaw or h/w problem affecting all watches.
At least I've got my 63 flights of stairs climbed for the day thanks to all the up/down changes!
It takes the p^ss that these expensive watches are released to the market with inherent hardware faults and Garmin remain ignorant of the problem. For a lot of people, accurate elevation stats is really important, as important as distance.
I've just noticed that for a cycling activity the elevation plot is much smoother with no 'sawtooth' effect. Have passed this onto Gramin support but they haven't given me much of an impression that they really care about trying to diagnose this issue although to be fair they did replace my original watch.
I noticed exactly the same thing on a ride the other day. The battery ran out in my Edge 520 so I used the 645M for the remainder, and was surprised with how accurate the elevation track turned out. Digging through some old threads in this forum it appears this was not always the case. And with firmwares prior to 4.00-4.10 cycling elevation was grossly understated. It would seem the change that fixed this on the cycling side introduced the regression we are seeing for running activities.
Apparently Garmin cannot be bothered committing the engineering resources required to fix both cases.
Garmin replaced my watch because if this issue also. Unfortunately the new watche's altimeter is just as bad and inaccurate. I really wish they would fix it already. It's been a year. Or at least just an option to disable the altimeter and default to GPS elevation data.
You did Settings/Sensors/Altimeter/Calibrate, in order to calibrate barometric altimeter with GPS setting and/or you own input?
Be aware that a barometer altimeter is good when it comes to measure RELATIVE height, as long as the weather doesn't change much. However, it won't have an accurate ABSOLUTE height without calibration, because this depends on current barometric pressure and therefore on the weather situation. That's physics, not bad software ;-)
Dude, I'm Dutch, we do know at what altitude we are here in Holland everywhere, not difficult, it varies between -30 and 30 unless you are in a balloon. My altimeter showed 1675 m climb during a 5k training right now (remember, this is the POLDER). I calibrated it to the correct height (+4m), the GPS was showing -7, but now it is showing -2290. Sure, these are the lowlands, but this is a bot too low even for us.
This craze started after the last firmware update (Fenix 3 HR, firmware 5.0), even the barometer is doing strange things.I am right now using a watch with a bunch of completely useless sensors, temperature (well, it's still skin temp, ok with me), barometer and altimeter. What's next? GPS going to show I'm in Australia ? (Ah, yeah, I powercycled it a few times, I'm sysadmin I do know a wee bit about how stuff works).
Or you could buy a Garmin with a barometric altimeter that works properly such as a Fenix 5 Plus or 935.
Fénix 3 HR, same issue and AFAIK the sensor is the same as in the 5. And it's even worse as you cannot correct this data. Strava still happily shows 1650 m after hitting the correct button and in Garmin Connect it's inactivated.
The only option that I see would be to disable (yet another) sensor and see if it shows the GPS data, while innacurate it will at least not show as if we had the stolen the Mont Blanc and put it here in Holland.
Did anyone ever hear of a fix or even get an answer for the 'sawtooth' elevation graphs that I still get from my 645? Garmin's suggestion was to replace the watch (for the 2nd time!) just like they suggested replacing the watch for the freezing after saving issue that showed up a few months back.
If I do a cycling activity then the elevation graph is almost level (on the same route as my sawtoothed running activity).
Do see any difference if the outdoor temperature is for example only 1-5 °C or if you use long sleeve T-shirt and put the watch on top of that? Or use jacket. Of course if you never have so cold, then this is not applicable. My Garmin works better when using it on top of long sleeve and the outdoor temperature is max few °C compered when the weather is warmer i.e having something like 15-30 °C and use the watch in skin.
