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Heart rate measurement suddenly too high on FR35

Hi there,
I have the Garmin Forerunner-35 for 8 days now, and the first 7 days I was quite happy with the device. I tested it with another heart rate device during running and cycling and I was quite happy with the result. The wrist sensor did a good job regarding the heart rate accuracy (although you need to wait one minute before the FR35 displays an accurate value)
But now I suddenly experienced a big error with the heart rate measurement during my run. The first half hour was ok, but then suddenly the displayed heart rate value was way out of my actual heart rate. (continually +50 bpm too high) I tried to solve this by restarting the workout or cleaning/drying my wrist, but nothing helped.

The only difference with the other workouts....the outside temperature was quite lower (at around 0 C / 32 F) . So I suspect that the FR35 will give wrong heart rate values when the surrounding temperature is too cold. (My wrists were also pretty cold, since I was wearing short sleeves)
Does anybody else experienced the same?
If this is the case, I think I will not return the FR35, since this rather cold temperature is not so frequent here (The Netherlands)

0 5341039 over 3 years ago

I am receiving an alert at ever lap (mile) that my HR is at 255. This alert happens three times right after a new lap is started. When I review my data on connect after the run, the HR is correct - and I'm not anywhere near 255. So I believe the watch is working correctly but the alert is a bug. I'm unsure how to fix this as it's annoying to get these alerts constantly. I've restarted the watch and my skin is dry and lotion free. And like I said, the device is reading my HR correctly but still alerting me with this ridiculous reading. Anyone experienced anything like this?

0 mccl5527 over 3 years ago in reply to 5341039

I'm experiencing the same thing on my 35. Typically it reads HR of 130-145 depending on the effort of running, generally 10-11 minute/mile for my age. But in the past few months it will suddenly spike to 175-190 and will drop to the 150s if I reduce my speed to a crawl, then will quickly elevate if I even gently try to increase my pace. Out of an abundance of caution my doctor had me wear a 48-hour monitor, undergo a resting EKG, and finally a stress test which I passed with flying colors. Reading these posts gives me assurance that it's not me, but the watch. Interestingly the high HR becomes less common when the outside air temperature is warmer, go figure.

0 JoeD over 3 years ago in reply to mccl5527

Try To Wear the Watch Further Up the Wrist and a Little Tighter.

For Activities an Ant+ Chest Strap does Wonders for Accuracy.

0 mccl5527 over 3 years ago in reply to JoeD

Thanks Joe, I'll try that. Can you recommend a chest strap that's compatible with the 35?

0 JoeD over 3 years ago in reply to mccl5527

Garmin HRM-Dual

PART NUMBER 010-12883-00

This One Works

0 mccl5527 over 3 years ago in reply to JoeD

Thank you, I'll take a look at it