Fenix 7 HR accuracy

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)

  • I think if it is still under warranty, then send to Garmin for warranty. I guess sometime we are un-lucky. 

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

    Garmin acknowledged that there is HR problem long time ago  but problems are still here and there is no official feedback about actual plan to fix it it, so I would not hold my breath for Jan 2025. This is not their priority for some reason, and in forerunner forums Garmin closed all earlier threads in which HR issues were discussed. 

    I think if it is still under warranty, then send to Garmin for warranty.

    Good suggestion. 

  • Thanks.

    I think it's the most advised choice.

  • Hello everyone,

    So I asked for replacement. I received a "recertified" watch. I'm a bit disappointed as mine was only 6 months old and looking as brand new. I was not expected a refurbished watch.

    Received on FW 18.16 (not sure .16), downgraded 15.77. System setting for measures is 1second, GPS only.

    I ran for a test: first run was endurance for 40min. Seemed ok at first, I mean "seemed to match the effort" but sometimes showed like frozen HR. And around 30min running, a HR 15-20 bpm higher than I was "feeling" : showed 168, I'm pretty sure I was around 150-155. But it was not a scientific test, only based on my own experience.

    Red is measured HR, blue is "adjusted pace according slope" (don't know the english garmin expression)

    Second run was sprint repetition: 30-30 ten times, targetted pace 3'50 . I know for sure that with such a short time effort the optical HR is not as accurate as HRM. But it was a test to at least see whether the watch can be trusted.

    Here is the graph. To me this "recertified" watch is as f.cked up as my first purchased watch. As a comparison, I ran with a friend wearing a fenix 6s pro: the Fenix 6s pro showed changes in HR matching the the changes in pace.

    Blue is measured pace, red is measured HR

  • Lately, perhaps as a result of software updates, the watch has been giving low and inaccurate heart rate data while running on trails.

    Previously, there was a problem where the watch only gave correct heart rate data after a few kilometers of running.