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Fenix 7 HR accuracy

7892400
1 month ago

Hi everyone,

I own a fenix 7 standard since may. Out of the box I was asked to update it to 17.28, if I remember well. I've done some runs with 17.28 and HR was totally crap. I made some research and ended up in the Garmin forum. Looking at the different subjects I found it could be a good idea to downgrade to 15.77.

But even with this software version, HR was inaccurrate compared to my forerunner 945. So I bought a HR monitor belt:  HRM dual by Garmin.

With HRM, everything seems to be ok, and so, I remained with the old 15.77.

But four days ago, I was planning uphills fartlek, tried to pair the belt with the fenix and nothing happened. My 6 months Garmin HRM is full of liquid inside and out of service.

Ok, I went for the run without the belt, counting only on the wrist hr monitoring: endurance for 25min, then 7 times uphills for 1'30'' (pace of the 10k, 8% slope). As expected, HR is totally f...ed up: endurance hr was 20 puls higher than usual, uphills hr less than expected (should have reached my max HR) with no real decrease during 3' recovery time (down the hill).

Back home, I decided to give a try to the latest 19.38: saved settings to Garmin connect, saved other settings on computer, performed hard reset, received and installed 19.38. Hard reset again, reinstalled the save of the settings, the other savings on computer. Performed soft reboot.

No battery drain, one bug noticed is the light with the wrist movement.

Today was endurance (135-155 puls) and the time to give a try to 19.38 with great expectations. As you can imagine, if I am writting now, the result of the test is very poor: HR seemed ok at first, even if I experienced a high delay in change of HR. I mean I expected some delay but not as much as 20-30 seconds.

Then I climbed a small hill I use to run at the upper level of endurance ~155 and then the HR showed 184. And in the descent, when usually my HRM shows less than 135, the fenix still showed 187. I stopped running, was totally immobile and the HR dropped in less than 3 seconds to 115 , which is my normal rate after a descent and not moving anylonger.

This kind of behaviour repeated several times during the run. Walking shows a slow drop, being immobile a huge and fast drop (30-40 puls).

I must specify that as I've read a lot to understand the poor behaviour of my premium watch, I wear the watch above the bone, I shave my wrist, I  wear the watch tightened. I can not tighten it more, I can assure you.

So my questions are: have you experienced the same HR problem, should I wait for an update to solve that, or should I claim for warranty? For both Fenix and HRM?

Thanks for the time you will spend reading and answering this.

(Reason of edits: text correction)

  • 0 1 month ago

    I wear a Fenix 7 for running. I will occasionally wear a HRM strap if I'm doing short intervals as it responds more immediately to HR changes but the Fenix is fine for most activities. 

    FWIW my Garmin HRM strap is over 3 years old and still works perfectly, despite that I use it for both riding and running. 

    In summary, I don't think there's a design flaw with either, but perhaps yours are both faulty for some reason. I guess that only Garmin could investigate them to determine why 

  • 0 1 month ago in reply to druidh

    Thanks a lot for your reply.

    First I had a forerunner 945. Difficulties to catch gps signal, sometines got it after 2km, sometimes 10k, and after 18 months hr was quite irregular. But with no point of comparison, I asked for warranty almost at the end of it. The new one was totally different: gets signal in less than a minute, hr ok.

    That's the reason why I'm posting. With no comparison, it's difficult to guess what is normal and what is not. And on the internet I don't see a lot of people complaining about hr inaccuracy for fenix 7 even if I guess some of then use it with a belt. Around me nobody is complaining about the wrist hr of the fenix, but I don't know how they use it.

  • 0 1 month ago in reply to 7892400
    7892400 said:
    And on the internet I don't see a lot of people complaining about hr inaccuracy

    Really? If you did even a cursory search it would take you moments to find a number of threads from users complaining about issues with WHR on all Garmin watches with OHR and the F7 range too. So perhaps do that. 

  • 0 1 month ago

    In my case, Fenix 7 worked perfectly in all of firmware versions until now. I did some parrallel testing (same activities, different devices). I used F7 Solar sapphire, then connect HRM with my phone + strava (not connect with fenix). The values of HR are very close together for all of the easy run, tempo run, interval run. But in most case, the HR graphs of HRM chest belt are look smoother than the Fenix 7, but not too much different. Note: I am always wet like having bath during running, because of hot weather (above 30 celcius).

    Only 1 problem is with firmware 18.16: if connect HRM pro plus to Fenix7 18.16, after finished the activity, the HR will be inceased abnormal about 1 minutes before comeback to normal. I informed to Garmin support, and they admitted this is problem, will be fixed about january 2025.

  • 0 1 month ago in reply to Dr Phil

    Yes, dear Dr Phil, really.

    Some people are complaining, but for the last weeks it's not so obvious.

    I looked also in the beta forum, all the entries for different beta firmwares and no, it's not obvious. People notice battery drain, diseapearance of a thing or another, changes in things they used to like...

    I've found some reports of hr inaccuracy with graphs and so on but for the past weeks it's been not redundant.

    That's the reason why I'm begging for your own experience. And if two people in this thread don't notice huge difference judging by their comparison with a belt connected maybe some of fenix 7 are hardware deficient.

    And hopping too long for a sofware update is taking the risk to overpass the warranty of the product. And by this time having, to my opinion, a product which is almost useless.

    It's what I've almost done with my forerunner 945. And I regret not having claimed for warranty earlier.

  • 0 1 month ago in reply to David Nguyen

    Thanks a lot David to have shared with details your own experience.

  • 0 1 month ago

    I have multiple brands HR straps which I use with my Fenix 7. Software update 19.38 seems to have messed up the accuracy of two HR straps I've been using without any problems before.

    The heart rates with these HR straps during an exercise are constantly at least 30-50 BPMs too high.

    Have since updated to 19.41 and the problem is still there.

    I also noticed that if I use the optical HR sensor and select the heart rate glance, the heart rate jumps randomly up 70-90 bpms. Eg. while resting the HR is 50, I select the heart rate glance, the reading goes to "measuring" for a few seconds and then jumps to 140.

    Both of these functions have been working normally for 3 years on my watch.

    I can't think of an any other company which so successfully keeps sabotaging the functionality of their products.

  • 0 1 month ago

    Worth a shot, for the record though, I've not had the Fenix. My current daily use watch is the enduro 2 which has been awesome.

  • 0 1 month ago

    You can find on this forum some thread created by me. After several discussion with Garmin support and also sent back to them the HRM pro plus for testing. They did several testing and analysic, then they concluded: there is a problem with the software (I guess it is because of the connection issues). 

    You can see some thread that I created:

    https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-7-series/387085/fenix-7---firmware-18-16-heart-rate-problem---battery-is-ok 

    https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-7-series/387432/fenix-7-saphire-solar---firmware-18-16---all-ok-so-far

    Garmin said, they admit this is the problem and trying to fix in Jan 2025.

    However, there is 1 thing I think you can do: From 18.xx version, the fenix 7 and hrm will automatic switch HR signal if need  (Between Optical HR on the watch and HRM chest strap), this could be the root of the issues, maybe you can turn off the automatic switch HR in setting, then it could be help. Make sure it always get data from optical sensor OR HRM chest in 1 time only.  

  • 0 1 month ago in reply to David Nguyen

    So I'm still confused.: hardware (warranty) or software (hopping for Garmin improvement).

    I had the fenix 7 at first with software 17.28: hr was unreliable. Too high, too low, neither showing increases, nor droppings.

    That's the reason why I looked into the forum and downgraded to 15.77, which, from what I've read was supposed to be a "stable" version (If I remember what I've read Garmin implemented an algorythm taking into account pace and heart rate which was in fact fooling the HR on screen).  But HR was messed up. Once it was so totally different from what my hr what supposed to be (threshold running uphill at 1500 m elevation and the watch was showing zone 1) that I removed it to check whether  the green lights were working or not. During the rest of the run the HR was then stuck at 110 for 30 min.

    That's when I decided to buy the HRM dual. And because I really thought it could be a software problem which would be solved by Garmin.

    Now, I'm on 19.38, and nothing changed.

    Thus I supposed now that instead of being a fool and thinking that it's what not a faulty watch I should have thought differently: in may Fenix 7 was not a brand new watch. It was an item released 2 years ago. So no reason for youngness problem. Now, 7 months later, the watch is not serviceable as too many datas depend on HR: training, recovery, endurance, sleep, training calendar, suggested workouts...

    And since may, two major softwares have been released: 18.xx and 19.xx.

    Yesterday I ran with my forerunner 945: it's obvious it is not as accurate and fast that a hr belt, but the main difference with my fenix 7 is that the HR on screen was showing what I'was "feeling" during a 3 blocks threshold.