new 8 volt batteries down

an 84 year old gal at our golf club purchased a new set of 6- 8volt batteries 2 years a go. for her ezgo she has played golf twice in that time leaving the charger on.i have just checked them for her and half the cells were dry and the charger had stopped.
can these be revived??
i put one on an 8 volt charger(after topping up the water level) it only came up to 8.06 volts.is there anything i can do?