Non continuous HRV measurements

Here is the summary of my last 2 nights, again the heart sensor stops working. This morning, when I woke up and saw that it was not measuring, I looked at the temperature, saw the "sensor hub 0.0.1" again, and took off my watch. A couple of minutes later the heart sensor was working again and I could read "sensor hub 27.18"

I did a test a moment ago, I left my Garmin behind the window in direct sunlight; as soon as the temperature has risen after 10 minutes, the sensor has stopped working again and "sensor hub 0.0.1" was again there.

I still think that the problem is that as soon as the temperature rises a little (35 degrees is well below the limits set by Garmin) the sensor starts to give problems.

• What a mess, I miss my FR 245's.

Interesting. I also looked at the temperature graphs and my watch also regularly hits 35° or 36° during the night. But my pulse readings are not affected at all. They don't have gaps on the watch or in connect. But maybe if the watch got even hotter that would also happen to me. I guess I'll try the same setup you had, when it gets sunny here again.

I just realized while checking Garmin Connect that when the heart sensor stopped working last night, the battery was too hot.

Before update 17.26 this did not happen.

I've just been in the bath with my watch. The temperature sensor recorded about 10min of continuous 37degrees. Celsius. I checked the battery using the "Solar recharge tab" and it did not overheat. It also measured the pulse the whole time.

I would guess that if the watch is reporting battery overheating at 35 deg. Celsius, you'll have to claim the watch because that's not normal behavior. Unless it was happening to multiple people at once, then one could consider a SW problem.

But please take this with a grain of salt. It's just my feeling.

P.S.:

Lest I forget, after resetting with the illumination button, my watch measured HRV continuously for two nights in a row.

I started to experience this like 2 weeks ago, and gradually the periods when HRV was not recorded overnight got longer, and by today, the HRV recording was completely missing. In the beginning hear-rate was still recorded overnight, but by today, there were many periods when also HR was not recorded. To make it worse the watch even started recording false HR data today during my run, so it grew to the unacceptable level... How can I get this sorted out with Garmin? I just got the watch in april, but now it lacks its main functionalities... I want this to be solved as fast as possible, either repair, replace or refund, then I can buy a Coros instead of this ridiculous quality. Any thoughts? Did it get better to anyone?

Looks like the Heartrate Sensor died on your watch. Most of the other people with the HRV Gaps usually have normal heartrate measurements, which makes the problem even weirder. I can only recommend getting a replacement Unit from Garmin, as it is really easy and should be covered by your warranty.
Actually my HRV measurements over the last couple of nights were perfect, but the sample size is too small to know what actually caused that. Other than that I've been really happy with the watch and all the other features.

Mine is working perfectly the last two nights, I did nothing, so strange...

I think it really is the movement of the lower arm that is causing the gaps. I tried wearing the Watch on my upper arm for three non consecutive nights and every time got a perfect reading. During that time I got one good and two bad readings on the wrist. As the heart rate is measured perfectly on the arm and the wrist I doubt the Watch is losing connection to the skin. Also I noticed I sometimes wake up with about 20 Steps already counted, which would indicate the watch having moved a lot during the night. Maybe Garmin changed the movement sensitivity for HRV Readings in that update?

I don't think that you are right. First of all a watch is not supposed to be or designed to be worn on upper arm. 2nd, for me, and for many others here the watch used to work perfectly for a while (for me since I bought it in last April until now) and then started to produce this weird measurements. I already wrote to the support, the ask for some extra data to examine the issue let's see what they come up with.

As I have already said, the watch also worked perfectly for me and suddenly started giving wrong measurements. The timing coincides with the update to 15.19 in late May, which other people even in this thread have confirmed. As I have already said, even with my brand new replacement watch the problem persisted, so it is not a hardware problem.
The upper arm thing was just a test to use a less moving body part with good pulse measurements. It is a normal place for optical heart rate straps for example. In other threads people advised putting it on their ankle, which sometimes also worked.
I didn't say putting the watch on the upper arm was the fix, I said it produced good measurements and the only thing left I couldn't rule out as a problem source was the movement of the watch. If you have a different Idea, please tell me. I shared my findings so maybe other people could try the same and tell me if they have the same findings.
I am very interested in what the support has to say about the issues. As far as I know they are already aware of the HRV problem, but have not been able to implement the fix in the last two updates. That is the reason I am keeping on trying these things, maybe it will turn out to help them. Maybe it won't, who knows.