Charge 3 under-recording distance on GPS

[MattBirks]

Hello all,

I have read other users posting similar issues, but not seen any actual solution. For a bit of background, I've had my Charge 3 since Xmas having had a Charge 2 for a couple of years before that.

I wear the Charge 3 all the time and use it for step/sleep tracking etc, but primarily I track my (short) runs linked to the GPS on my android phone. The Charge 3 has worked perfectly well for all of these things until some time between Oct 3rd and Oct 5th, as I can see the 2 runs in Strava where the issue started happening.

Since Oct 5th the smooth line of my tracked run has regular short zig zags in it, like it's been folded back on itself, and the Charge 3 under-reports the distance run by some margin. For a 5km run it tends to now report about 3.7km. This is using the GPS from my phone, which I always ensure is connected before I start running.

I've checked the stride length and that's the same as it always was - although it makes no difference when using GPS anyway.

I've done multiple runs in different locations at different times and the same behaviour occurs. I've also recently upgraded my android phone. I have new phone hardware, new android version, and it's exactly the same,so is clearly not the phone.

I put up with it for a while assuming it was some glitch with the processing of the data at the FitBit end, but it's becoming really frustrating now - the primary purpose of my tracker (for me) isn't functioning.

Anyone have any helpful advice?

Matt

[MattBirks]

Here are a couple of images to show what I mean.

[Vivianna]

Mine is doing the same.  Its really annoying.  Tonight I ran 8k in 52 minutes but my charge 3 recorded 5.6k and therefore my pace is incorrectly recorded.  Ive tried rebooting the Fitbit but it made no difference.

[Rich_Laue]

Sorry @MattBirks the photos will not help for distance, but the path recorded looks good. 

As for GPS recording distance, their is nothing in the manual about this or that the stride will be auto calculated using gps. 

As for as I can see, the distance during the run is based on steps and stride. 

[MattBirks]

As you can see in the mobile app settings, the stride length by default is tuned by running with connected GPS.

Also, this is what the tracked run should look like...

This is the same parkrun after it had gone wrong...

The Fitbit recorded the first as the right distance and the second as just over 4km.

Clearly something has gone wrong with the way Fitbit processes the data it's getting.

Matt

[MattBirks]

I'm assuming that everyone else's Fitbit is recording running distance fine?

I'm off out for another run to see whether anything has changed...

If not, I'll be contacting Fitbit support.

Matt

[Vivianna]

My Fitbit Charge 3 started recording distance correctly about 10 days ago.  I didnt change anything so no idea why????

[MattBirks]

Vivianna,

Was it providing duff distances before 10 days ago?

Mine was still way off last Sunday, so clearly whatever worked for you hasn't helped me yet.  Thanks for the info though, good to know things do change in the background.

Matt

[MattBirks]

Just been on with FitBit support. Have done a 'long restart' under instruction. Will see how that pans out tomorrow morning.

Matt

P.S. These are the instructions...

1. Connect the device to the charging cable.

2. While the device is plugged into the charging cable, press and hold the button down for 15 seconds.

3. The device turns on and shows a battery icon. Two vibrations occur: first a short vibration, then a medium vibration.

4. The device turns off.

5. The device turns on and shows a progress bar and short vibrations occur. The progress bar completes. Note: A total of 7 short vibrations occur.

6. Remove the device from the charging cable. The device shuts down.

7. Important: Plug the device into the charging cable again.

[MattBirks]

After the long restart, just as bad if not worse. Followed my local 5km parkrun route this morning, WiFi off, connected GPS before starting, and the Fitbit recorded it as 3.38km. 

Map of the recorded route below, still a zig zag mess...

 

[Vivianna]

How annoying!  I still have no idea why mine suddenly stopped working then suddenly started again.  Its been accurate for my last 5 or so runs.  I dont now trust the data it provides (sleep, heart rate, etc) but for now there is no zigzag mess.

[MattBirks]

The next step from FitBit support is to manually configure the stride length, which involved me and a measured running track - which I don't have to hand, so this is going to take time to sort out.

I will make it happen though and report back.

Matt 

[Andrei_S]

I have pretty the same issues with my Charge 3. Sometimes zig zags appear on my route. Moreover, few months ago they were counted in a total distance. But what is more annoying that my tracker often looses connection with my phone. 

[Kaflemd]

Watching. I have the same issue. Just an FYI, all of my distances are recorded correctly if what is shown in km is actually miles. Nightmare as throws out pace, etc when showing it as km but actually recording miles (e.g. 5k is 3.1 miles and fitbit shows 3.15km).

[MattBirks]

Ran yesterday morning. Worked out the route on OS maps to be 3.6miles or 5.8km, Fitbit tracked 4.48km, so 77% of the distance. Which is better than it has been, but still pretty poor.

Haven't found a local 100m track to check my stride length on yet.

Matt

[MattBirks]

Another run this morning. OS maps measures it at 5.2km (3.23miles), Fitbit with connected GPS measured 3.82km (2.37miles). So, only measuring 73%. So getting worse.

Notice my running stride length is still auto decreasing within the Fitbit app.

Still haven't had access to a measured track to calculate my stride length manually.

Matt

[MattBirks]

Same run as Monday this morning with connected GPS and the Fitbit recorded distance and route map look perfect. Seems to have become totally accurate since Monday with no changes that I'm aware of.

I have noticed that my running stride length has auto-adjusted back up, so clearly something is going right with the Fitbit algorithms again for me.

For info, auto calculated running stride length:

25/11 - 87.3

2/12 - 84.9

4/12 (today) - 88.5

Route map from Monday...

Same for today.... 

Same run, similar weather, same Fitbit, same phone.

Looking good now. No idea why.

Matt

[Rich_Laue]

Fitbit says that the running stride is auto adjusted while using GPS. They do not claim this for a gps monitored walk. 

@MattBirks glad it is working. 

[MattBirks]

Not all rosy. 3 identical runs since my last post, and all have been under-recorded by varying degrees. Recorded route maps also showing zigzags again. Also stride length has been auto-adjusted after each run.

So, run that should be just over 5km (recorded on 4/12 as 5.01km)

Friday 6th 4.65km

Monday 9th 3.74km

Today 11th 3.88km

So, nothing is fixed. Run on 4th was a lucky one off.

Matt 

[MattBirks]

Another 5km measured parkrun this morning, which Fitbit recorded as 3.26km. getting worse!