new, undocumented Garmin Heart Rate Feature
A couple of weeks ago Garmin Fenix 7/7 PRO optical heart rate sensors remained mysteriously on even when a heart rate monitor was correctly paired and in use. Why?
A New Feature
This is a new feature that boosts security and consistency but may have a small hit on battery life.
Firstly the security reason is specifically linked to Garmin Pay which requires a PIN code to be entered for each use unless the watch detects it has been consistently on your wrist since you first entered a PIN. It seems that the only way Garmin can detect the watch on your wrist is by firing up the ELEVATE heart rate sensor.
Secondly, Garmin confirmed that the optical heart rate is continuously reading your heart rate during activity but NOT saving it when a chest strap is present. However, if you miss a beat or two or if the chest strap battery dies then the optically-derived heart rate is used to fill the gaps. I thought it had worked this way for quite a while but could be wrong, and I seem to remember once analysing detailed HR records with the FIT file inspection tool to find that a particularly problematic file had indeed switched repeatedly between HR and oHR sources (the source of each record was stated, IIRC)
Should I turn It off?
I’d leave this feature on but you can disable it in one of two ways
Manually disable the OHR sensor before an activity and manually enable it later
- Menu> Sensors and Access> Wrist HR> Change to Off
Alternatively, create a Power Mode with the OHR off and add this power mode to the activity settings of every activity you are concerned about.
- Menu> Power Manager> Power Mode> Create New> Select a Power mode, or select Create new> Ensure Wrist HR is disabled
You will probably also find that you get more frequent dropouts than you imagine when making unusual movements when running and when swimming.
Models Affected
I don’t have a complete list of models affected however I would assume it is fairly extensive and more likely linked to the presence of Garmin Pay. So it will at least be on all watches with Elevate 4 and 5, probably going much further back to Fenix 5.
How to Guide: use Garmin PAY with most banks – here
Battery Hit
There will inevitably be a battery hit but it will have a trivial battery impact on the current generation of ELEVATE 4/5 heart rate sensors.
More
There is a chance that Garmin might release another new HRM in the next couple of months. This change might have some implications for that or for the newly announced automation for recovery heart rate calculation.
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I don’t think this feature is new. If you have a card in Garmin Wallet, the watch keeps the oHR on by default. I think it doesn’t (didn’t as I have not checked in a long time) keep it on if you do not have Wallet configured.
You definitely do need to use the port manager to turn of the oHR in order to be sure to get the power budget advantage of an external HRM. This will de-authenticate Wallet each time you do an activity with the oHR disabled and you have to use the PIN to make a payment. I do this so infrequently that I always have to use the PIN in reality.
The filling in bad data may be new. But frankly if the watch felt it needed to that it should alert you, mark the FIT file and Garmin Connect should warn you that there is a fault in the external HRM. Otherwise it may take a while to notice the HRM is pants.
Maybe only watch with active development.
F7/E2 Series
FRx55/FRx65 Series (i saw many report about this new behavior)
Venu3/VA5
Chest straps are either very accurate or wildly off, whereas the typical failure mode of optical HRM is being slow at detecting fast changes. Observing both and picking the least implausible would be a huge improvement for people like me who see many obvious HR failures but aren’t dataphile enough to invest time on manual cleanup.
Yeah, afaik this was always the case from when Garmin pay was first rolled out.
Back when I used to have some connection drop issues to my chest strap (maybe 3 years ago with an f6), I noticed it would switch to using ohr, but the reading would always start reading at 80bpm and gradually move towards whatever my actual hr was.
Maybe they just fixed that so it’s got a valid reading immediately it switches?
Happened to me last weeks when that happened it says like HRM reconnected and then gradually go from 80 to a fair expected value during the next minute 🙂 so still happening with epix gen 2 pro
There is by default such a power mode, it’s called jacket mode for when you wear the watch over a jacket.
I really don’t bother to use it, but recharging once every other week is fine for me.
It has been this way for years, there used to be an external app/feature at the Garmin store (maybe still is) that would enable recording of both readings in separate fields, great for comparison.
that’s what i thought. the comment in the article from Garmin implies it’s new or maybe that something is newly altered.
I’m fairly certain this is new.
I noticed it a few weeks ago, my HR was far lower than what id expected for the pace I was doing, so I looked under the watch and saw the green light was on so I was thinking it was taking readings from oHR. It wasn’t, but I thought the fact it was on while Chest strap was connected was odd as when I last checked, probably early last year, it was definitely off.
Security is not the reason, if Garmin Pay was unlocked it always stayed on, it only turned of if Garmin pay was locked by PIN anyway.
Garmin pay locks when the device is removed from the wrist.
i got the impression that the ohr had to stay on to act as the on-wrist detector (there are other ways of doign it but i think garmin chose that way)