Hey. I’m a novice and still learning myself. Since you replaced the converter/charger, there appears to be no link to the batteries. Does the wire from the converter go through a solenoid? Maybe that solenoid is not working. Does the battery disconnect have a manual switch, or is it a solenoid? Trace the line from the battery to the converter. Also, check your ground from the battery to the chassis or maybe back to the converter.