Non Car Related Question

If this is not the place for this type of question - kick out the post -- I'll understand. -- I have a, 2003, Club Car Golf Cart with 48 Volt, Interstate Batteries. The batteries are supposedly (??) less than 2 years old. - When I charge the batteries the indicator, on the dash, goes to full charge, but after 15 hours of charging the charger only drops to 6 Volts, and does not shut off. - It should shut off when the batteries are fully charged. -- Am I headed for replacement batteries ?