HenningL This generally works via the Zendure App - Problem: SOC min can be set at max. to 50% via the app. So If you are at near 100%, it may take weeks until battery level is down to 50% and the system finally shuts down.
I scripted the procedure in Home Assistant, from there, SOC min can be set to 100% which for me solves the problem.
Backside: Somehow, once I set SOC min to > 50% via HA and SF rebooted, SF does not accept new SOC min settings from HA - but this is cured by setting SOC min via the Zendure App inside the normal 10-50% range.
One more remark: I am using a custom zero feed-in via "Manual Power Control" from HA, which I switch off for this reboot cycle - not sure If this makes a difference.