With shore power plugged in use a multimeter to check voltage at your batteries if it reads 13.6 vdc or better your converter is charging batteries.
If it is 13.2v dc it’s on maintenance charge, now unplug shore power, check batteries again with no load less than 11.9vdc they are dead.
If 12.3v dc they are only 25% charged
If 12.6v dc they are fully charged.
If 11.9v dc or less check water level in each cell water, it must cover all plates in each cell, if low visit your favorite supermarket and get distilled water, fill each cell to cover plates, plug in shore power or start generator.
Give them time to charge and test again above.
