Instinct 2 - solar charge not working after USB charge

kiecherb said:

To see when the instinct 2 solar is below 90% how it will behave.

Yes, that makes sense. The permanent upping of the battery when it is (almost) fully charged would harm its longetivity.

Finally, the article My Instinct Solar Watch is Not Solar Charging | Garmin Customer Support mentions it here (although it does not specify the exact range):

When the Instinct® Solar is at full charge or unable to accept solar charging, there will be a gap in the graph displayed on the Solar widget. 

Like I said, none of that applies in this case. You won't find the situation I'm experiencing described in the manual.

Interesting. My Instinct 2S Solar battery is currently at 46%. I left it sitting in bright sunlight and can confirm that the Solar widget is now displaying the harvested power as expected. 

I wonder then if this is indeed a new change, as kiecherb highlights, and that it may be a good idea for Garmin to have the Solar widget display the "check mark" (or something appropriate) when the watch intentionally shuts off capturing sunlight when it falls within the specific shutoff range? This would make it obvious to the user, particularly when the watch is not at 100% or hot (showing the thermometer icon). 

Ok, so I've just done a few tests.

Watch has been sitting in the window for a few hours, graph shows solar charging. Its not in full sun, but the graph is ramping up as expected as the day brightens.

Connected to USB for 2 minutes, enough to increase from 27% to 28%, then returned to window.

After 15mins or so check solar graph - it has resumed solar charging at the previous rate (about 20% of max solar charging rate).

Returned watch to USB charging, left it a while longer this time, up to about 45% charged (it showed 10 days), then back to solar charging.

Looked at graph after about an hour - the graph has dropped to just above a trickle charge, despite the sun having now come round to full illumination on the watch (previously the sun was behind the window).

Power cycled watch and returned to window. Checked solar graph after about 20 minutes. Yup, the graph has made a step-change up to 100% solar charging rate (the expected rate under full sun).

In summary, throughout the battery has been below 50% charge. After a short (2 mins) period on USB charging there was no adverse effect on solar charging. But after a longer period of USB charging the watch then failed to take solar charge properly, instead limping along at a few percent solar charge rate even under full sun. A power cycle instantly returned full solar charging 

I'm having this same problem. I just got the watch 2 days ago and started trying it out. First Garmin and I have no idea how it functioned prior to this update.

NOW WATCH UPDATED TO 13.21 - No change to the above behaviour. After a period on USB charging the watch will no longer accept solar charging, until you power cycle the watch.

That almost seems like the built-in overcharge protection that normally kicks in when the watch just comes off the charger is, for whatever reason, not switching off to allow the solar charging to resume (requiring a restart to reset it). Perhaps a bug somewhere relating to the resistors that monitor battery temperature?

I’m facing the same issue as well, thanks for the post

Yep, I can confirm that my wife's Instinct 2S Solar is no longer solar charging after a USB charge, until the watch is rebooted. Running on latest update.