Will the inevitable nightly height calibration drain my battery? How is it supposed to work?

KrapfenKringel said:

But what does it actually do?

KrapfenKringel said:

So how is this supposed to work?

It does exactly what calibrate "not during activity" has done for a couple of years.  If you have a sleep window set and you're connected to Bluetooth, it will take the position of your phone and use DEM to calibrate your elevation during that sleep window based on the phone's given location.  Yes, if you live on the 20th floor of an apartment, your phone will give a location at ground level and the calibration will be off.

KrapfenKringel said:

I don't keep it connected 24/7.

If there's no connection, the process won't take place.  There's no excessive battery drain because the process doesn't start unless there's a Bluetooth connection. 

KrapfenKringel said:

At best I get a wrong height every night that luckily is corrected when I start an activity

No.  It won't calibrate to anything without a Bluetooth connection.  And why would you be lucky to get a correct reading after starting an activity?  How would getting a correct position because of a nighttime calibration differ than any other time you're calibrating elevation? 

KrapfenKringel said:

At worst its draining my battery trying to get information it can't get

No connection, no battery use.

KrapfenKringel said:

(same rules of the watch would apply to my phone, it also does not know or can find out at what height its located)?

GPS reception works quite differently than a cellar signal.  If you're at ground level the phone will know your location and the feature works perfectly. Have you never made a phone call or text indoors?

You're turning a mole hill into a mountain. 

"Doing nothing" with BT off sounds good. As for the "what it always did" I always had it turned off (which is not possible anymore) since I thought its pointless.

I would be lucky to get a correct reading on the start of an activity since I would not be on the 20th floor anymore and it could receive a GPS signal, cause I'm outside for my activity, so that's the only situation where a calibration would work. I clearly pointed out and you acknowledged that my nighttime calibration would be off, if I forget to turn BT off. What is there not to understand? 

Your other point is invalid as I pointed out there is no GPS reception in my flat and nothing is at groundlevel, as I said. Phone calls have nothing to do with this. Yes the phone would be located by wifi, but that does not give height information and would lead to a false DEM height as you pointed out.

It would be so easy to make an algorithm that worked for sleep altitude calibration (or at least in most cases)

1. Register rough GPS coordinates/boundary of "rough" location where you sleep (200m radius usually more than enough) 

2. Tell watch if I sleep within those location boundaries - my sleeping altitude is "XX meters" - no more - no less.

2. Get internet pressure from reliable source (not the current Garmin Weather supplier) - and update the pressure. 

3. Make room for X number of locations with associated altitudes. Then make room for location exceptions where it should NOT auto calibrate (like hotels)

It would not work at repeated visits to a hotel with more floors - but it would probably "catch" 95% of altitude calibrations. I usually sleep at the same 3-4 altitudes 95% of the time (different locations) 

You could even make a "during daytime" office calibration (Calibration altitude / Are you at your "office" location / y/n)

KISS (Keep it simple stu***)

Not even there is a need to tell tho watch. Connect could do the math and pass the correct elevation. Connect has the rough position estimate at least on Android.

I tried the 20.00 version with AutoCal On + Sensor Mode Auto settings overnight with the phone near and connected. The phone had internet connection. In the morning, the altitude had not changed from the altitude I had set earlier (which is not the DEM altitude of my location). When I did the same earlier with beta 19.77, overnight calibration would set it to -100 meters.

This could mean that the overnight calibration failed for some reason, or that is not active with this setting, despite what's mentioned in the release notes.

I don't know why I am intrigued by this - I have a perfectly good workaround, but still have an odd need to find out why they made this change and how it works.

Connect can not find your elevation. Height maps are not very precise. In reality what you get on most is an interval (you are between 44 and 54 meters of altitude) is usually the best "resolution".  Some places have better "resolution" others have a lot worse.

And that does not sort out if you are sleeping on ground floor , 1st, 2nd or 3rd (etc) floor. 

I tried both the "Nightly" and "On" settings with my phone connected overnight, and both don't result in jumps in the barometer or altimeter graphs. Altitude drifts a bit, depending on the weather. Either the calibration setting makes no difference or the re-calibrate is only done when the difference detected is very large.

Maybe the completely wrong nightly calibration I saw earlier was the result of user error.  I had forgotten that the fixed weather location was set to a place 200 meters higher than where I live.

All in all, it's working OK-ish, but not as good as it was. Battery usage seems totally normal.

In my case the phone has to be charging for the the calibration to work and of course the gcm service should not be suspended by the OS (eg. Huawei EMUI has an agressive memory management to conserve battery).

"Troubleshooting the fenix 6 Series Altimeter and Barometer | Garmin Support" support.garmin.com/.../ (under Auto Calibration: Not During Activity, currently known as Nightly) says: The watch will calibrate the altimeter once every night during the user's sleep window. A Garmin Connect app connection is required for this feature to work, as it uses location data from the phone and compares it to the DEM information.

Point you attention to "phone location data" and DEM (if found on the watch, or retrieved online), so the watch GPS should not turn on at all. Phone location indoors should be coarsely accurate if you use wifi or cellular location and don't have GPS reception. But this still doesn't explain why the elevation after calibration is junk, unless this feature has garbage code  

Imagine my OCD levels as a software QA when I see a feature that's ify at least and the intended behavior is not even described in the latest user manual revision

Makes me wonder what students in what basement are doing the development for this high-end product line...