Why doesn't body battery decrease with activity?

To add to this body battery confusion - after sleeping over 8 hours and waking pretty refreshed after my hike, body battery did not recharge at all during sleep and just continued to drop.

This seems really wonky logic to me, what is going on?

2953131 said:

This seems really wonky logic to me, what is going on?

Post the screenshot of your daily Stress graph. The Body Battery recharges when the stress is low (blue lines in the graph) - it menas when your heart beat is driven by the parasympathetic branch of the nervous system (the HRM is detecting high HR Variability), and it decreases when the stress is high (orange lines) - the HR is driven predominantly by the sympathetic branch (the HRM is detecting low or no HR Variability). So if it does not recharge, there is some problem with your HRV, or with its detection.

2953131 said:

But why doesn't the body battery decrease on a 8 hour hike ?

Hard to tell without seeing the HR graph, but the most likely reason is, that the device could not properly measure your HR or the HRV during the hike. If you hiked in low temperatures, then the peripheral vasocnstriction could be the culprit.

Another possibility coud be that you turned the HR off, or used a power saving mode, or the Ultra Trac mode.

That's the heart rate graph for the hike. I didn't use any power saving modes and the watch was under my jacket.

My normal resting heart rate is usually around 57bpm.

Yes, the HR was recorded, but  the HRV apparently not. Why was it so, is hard to guess, but Instict does adjust the Body Battery also during activities, so the long gap in you case seems to be caused by some proble with the HRM. It could be a bad fit, peripheral vasoconstriction, or other physiological conditions. You could try using a HRM chestbelt (supporting the HRV) to see whether it helps.

Thanks. I was considering a chest monitor so I can wear the watch over my jacket in colder conditions.

I'm not sure I understand though

the HR was recorded, but  the HRV apparently not

What does that mean? What is HRV and why would that not be recorded but HR is?

Edited to add, I think I found the info about HRV

It seemed to stop recording HRV as soon as I started the activity, which doesn't sound like an issue with bad fit or such as it was working perfectly fine before the activity and perfectly fine after the activity. With no adjustment to the watch or clothing.
I mean this definitely seems directly associated with the activity.

2953131 said:

It seemed to stop recording HRV as soon as I started the activity,

No, there is a gap only in the Stress levels during an activity, which is normal during all activities - Stress is evaluiated only at rest, but the HRV is measured all the time. Have a look at my BB & Stress graph below, including gaps in the Stress measuring while in an activity, though still adjusting the BB level.

... the only eventuality (though a very improbable one) that comes to my mind is, that the Hike Activity profle behaves differently than all the other ones. I use almost every activity profile available on Instinct, with the exception of the Hike - I use Walk instead. So, I'd suggest trying to record your next hike with the Walk Activity profile, to see whether it makes any difference. Though, I bet it would work in the Hike mode the next time anyway too.

Also try restarting your watch. The BB calculation seems to stuck relatively often, especially after firmware updates, and the restarting then helps to make it operating properly again.

And then, verify your Power Manager settings - at long hikes like that, it is likely the battery gets drained quite a bit by the long use of GPS, and that the watch starts shutting down some features. So make sure the HRM is not influenced by it.