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Body Battery Questions

Spectre
9 months ago

I recently purchased an Instinct Solar Tactical watch after my Vivoactive 3 (I've owned two of them) finally gave up the ghost.   One of the features that interested me was the body battery feature.   I exercise a lot,  and I often feel exhausted through the day.  I'm also not the best sleeper,  so I was very curious as to how the body battery would measure my energy level. 

After I first set up the new watch,  the body battery measured about 85 after the first night's sleep,  and by the end of the day,  it dropped to 5. The next night,  the battery charged to somewhere in the 30's, dropping to 5 by day's end.   There were a couple of days in the first week that the battery charged to close to 40, but not higher,  always settling at 5 by the end of the day. Garmin suggests waiting a week for the watch to normalize before relying on the body battery readings.   During the second week,  I charged up some nights to about 25, during other nights the battery reading didn't increase at all during sleep.   By the third week,  the battery showed a pretty consistent reading of 5 to 10 all day long, always ending the day at a reading of 5.

I called Tech Support,  who didn't have a solution,  but suggested that I reset the watch back to factory settings and set it up all over again to see whether the function would start working properly. I did that,  but after a week,  the readings again normalized to 5 to 10.

My wife has a Vivoactive 4S, which also has the body battery feature.  I switched watches with her to see whether my body would ”charge” her body battery function,  and how my Instinct would react to her body. 

Results:  The Vivoactive that I wore through the night started at a body battery reading of 51 when I fell asleep.   In the morning,  the reading was 17.  So during sleep,  I  drained the battery by 34 points.   My wife wore my Instinct through the night.   She started at a battery reading of 5, and in the morning it showed a reading of 100.

So……… is it possible that the Body Battery function must isn't compatible with some people?  The heart rate and stress functions (which figure into the body battery calculation) appear to work normally.

  • 0 9 months ago
    Spectre said:
    So……… is it possible that the Body Battery function must isn't compatible with some people?

    More likely your HRV was too low (stress high) during the sleep, hence depleting the body battery instead of charging. However, if you used the watch of your wife without resetting it, the HRV baseline (which is individual) was established for her, and not for you. You would have to wear it for couple of weeks for making any conclusions

  • 0 9 months ago in reply to trux

    Hi trux.  Thanks so much for the response!   My stress levels at night,  (which I just checked when I read your message) average about 10 through the night,  spiking occasionally to about 25.  The higher stress levels occur when I wake throughout the night.   

    Incidentally,  when my wife wore my watch and charged the body battery to 100, I wore it again the next day,  and drained the body battery from 100 to 5 by 5pm.  My average stress levels over the last 4 weeks has been about 50.  

  • 0 9 months ago in reply to Spectre

    Please post a screenshot of the BB Timeline graph of the concerned night as found at https://connect.garmin.com/modern/body-battery 

  • 0 9 months ago in reply to trux

    Here's a good day.

    Charged to 34 overnight,  depleted to 5 by noon.

  • 0 9 months ago in reply to Spectre

    Exactly what I wrote - quite high stress during the night, and the max stress during the day. BB charges only when the stress is in blue. When orange, the battery discharges.

  • 0 9 months ago in reply to trux

    So,  the blue bars are also a measure of stress,  but it looks like if that stress level is under about 25, they display as blue,  charging the BB.  Above 25 the stress bars change colour to orange,  indicating a drain on the BB.  What level of stress is typical at night?  If you look at the blue bars on my graph,  at night time they look to average out to around 10(ish).  Given how the BB line inclines over my sleep period, if you were to extrapolate the upward trend of that line, in order to reach 100%, it appears that I'd need to sleep until late afternoon.   

  • 0 9 months ago in reply to Spectre
    Spectre said:
    What level of stress is typical at night?

    Good sleep is all blue, but most people will have some orange bars there too.

    Spectre said:
    Given how the BB line inclines over my sleep period, if you were to extrapolate the upward trend of that line, in order to reach 100%, it appears that I'd need to sleep until late afternoon.

    Right. When you end the previous day with the BB completely drained to the absolute minimum of 5, then you either need even a lower stress during the night, or longer sleep, or some relaxation, or several consequent more quiet days and nights, to recover.