System is SmartSolar 75/15 with two series-connected 30W 12V solar panels charging two 12V 110Ah lead acid batteries connected in parallel. Settings are all default for lead acid except float voltage reduced to 13.5V from 13.8V. The system was installed in 2018 and was working correctly when we left the boat in october 2019.
Covid then prevented return until last week, when we found the blue light on the charger flashing indicating no charge being delivered despite sunshine and a battery voltage of 10.4V. After connecting to the controller and updating firmware, it seems that charging had somehow been switched off in the controller at some point during the two years absence, with no charging for the previous month's history and presumably for some time before that.
After recharging the batteries (which appear to be still partially functional) and re-enabling charging the controller again seems to be operating correctly.
So my question is under what circumstances does the controller decide to disable charging? (I don't even remember that option being present in the software in 2019 - maybe it's a more recent addition?) And is there anything I should do to prevent a similar incident in future?