[jklewissf]

Sorry, I missed the fact that they were gel cells when I responded before. The boiled battery is toast. It may have been charged at too high a voltage. Most gel cells wont tolerate charging voltages much above 14 volts. If you regulator allowed them to go to 14.2 or 14.3 you may have fried the battery. There is no cure.

There are little vents on the tops of gel cells. When the battery boils these vents are forced open and you should see little bits of stuff accumulated around the holes. This is a sure sign that the battery has been trashed.