Charge 5 can't keep HR accurate while using on-board GPS

[SunsetRunner]

DC rainmakers review ( always thorough) just came out with this revelation. Terrible news if true and probably be a cause for a product recall if it is the case here. 

Can we use this thread to post our tests on this and anything we see. I intend to do some runs with the Charge 5, Inspire 2 and maybe an Apple Watch (like my previous tests) to see what happens 

https://www.dcrainmaker.com/2021/09/fitbit-charge-5-in-depth-review.html

[Mont-Sly]

Thank you for posting this.  I haven't bought the Charge 5 yet.  If this proves to be true, I will seriously consider not purchasing.  To me it's an issue of quality control.  How can a device be sold when it can not accurately measure GPS and heartrate at the same time?  I returned the Sense because of the heartrate issues, which are well documented.  If something basic is wrong with the watch then it raises doubts about the overall quality of the product.  

[Tristannyc]

There is a counter to this from Des who is friends with DC Rainmaker.

He said he didn't have the same issues and it may be more of UK thing vs US thing than band thing:

https://www.youtube.com/watch?v=p3BIukVgFYY

[jasrot]

FWIW I just received my C5, and can get a GPS signal in my house with the band on tight. I’ll try it out on a walk this evening. 

[jasrot]

I had no issue using GPS and Heart rate on a walk. So I’m not sure if this issue is sporadic, but so far so good with me. 

[SunsetRunner]

Going to do the on-board GPS run tomorrow AM. Did you have your phone with you? Mine was okay too but realised I had my phone and it more than likely used connected GPS

[jasrot]

I had no phone with me.

Get Outlook for iOS

[nihahi]

If you can get GPS while inside your house, that pretty much tanks the standard excuse of "tall buildings, trees and cloudy skies" for GPS failure...

[SunsetRunner]

This is true. Be interesting to see what excuse Fitbit uses if the GPS fails on runs as the watch rolls out mainstream. 

[SunsetRunner]

Sorry for the delay as I have had battery issues that I wanted to test out before bringing GPS as a variable into the mix

Using a brand new Charge 5 (I now have two pairs, Fitbit really have a Voodoo doll of me) and two runs later, I must say that GPS and HR were solid, contradicting DC Rainmakers experience. 

Well the first run (5km) was solid on both HR and GPS. It looked identical to historical connected GPS runs with my Inspire 2 & Charge 3. Did better than my old ionic which used to cut small sections that added up to a few 100 metres each run.

On the second 7.5k run, all was sort of perfect on HR but GPS gave me slightly more than historical runs. I am talking an extra 250metres so not the end of the world. I also think that was due to running through a wooded area, the Fitbit probably did that gubbins (that all Fitbits do) where it uses your stride length etc to fill in the blanks on distance. 

When I exported the run to Strava and used the "correct distance" function. The 7.5km was bang on accurate which tells me that the GPS data from the watch was rock solid but the Fitbit app was doing its usual nonsense.

Based on this, I can't fault the Charge 5 at present. Fitbit needs to hand back the voodoo doll 🙂 

[t.parker]

@SunsetRunner the distance Fitbit gives you is not based on the GPS (never was). That's why Strava correction worked (it replaced Fitbit distance with the one based on the GPS route).

[SunsetRunner]

Wow. I never knew that, I always thought it was GPS unless the signal was lost. Thanks for that info there @t.parker 

Wait!! That means some of my best times were probably a couple hundred of metres too short 😞

Ignorance is bliss 🙂 

[t.parker]

Fitbit does it similar to other watches, uses steps and stride and updates stride length using the GPS later (so if you lost GPS connection it may badly affect the distance of your next runs if you allow Fitbit to recalculate stride length automatically). This has been proven many times by users regardless of what Fitbit claims. I don't expect Charge 5 does anything different to previous watches. I used to check the actual GPS distance by uploading exported TCX files into http://mygpsfiles.com/app (it's pretty much the same as allowing Strava to correct your distance).

Edit: Oh, just to make sure (I don't own Charge 5 and I won't). Wait for the GPS connection established and start stepping in place. Observe the distance to see whether it increases despite you're not moving forward (like in previous watches). This will verify it.

[SunsetRunner]

I will give that a try but I am certain you are right as it would explain the odd short runs I have had in the past after runs where GPS dropped out.

That is such a terrible way of doing things but with Fitbit, nothing surprises me anymore.