Victron energy multiplus 48/5000/70-100 BYD off grid solar system
The system was fitted 4yrs ago and usually works perfectly but last year noticed that when the batteries were discharged down to the 40% mark ( couple of cloudy days ) without any change in load they would rapidly discharge to 8 or 9 % in just a few hours.
This has happened a few times now, above 50% percent no issues.