PT you might be right about the victron monitor
But that will not compensate for a sulphated battery system
That no longer has the capacity the monitor is programmed with, 12.1v is Not the correct voltage of a system at 78% SOC, the SOC says he used 22% by counting the power used, but the volts reading indicates 50% SOC,
The batteries real capacity is only HALF of whatever the monitor is programmed for, time for some new batteries , and a re-examination of the use/recharge regimen, maybe there is a bad cable or dead battery, and he is only using half of the installed batteries, or the cables are good but the batteries are heavily sulfated
