Some years ago I put in 2 new Trojan golf cart batteries for our house bank. About 2 months later I went down to the boat and noticed: 1) A funny smell and 2) The Link 10 battery monitor showed about 15 volts.

The ferro-resonant charger had run away and was cooking the batteries. They were pretty warm to the touch. "Damn!" I said, "my new batteries is wrecked!" After they cooled down I found the plates dry with no sign of electrolyte. Brought them up with distilled water (lots of distilled water) very carefully and installed a new 3-stage charger. We kept the boat 8 more years and the batteries still had their original capacity as measured by the Link 10.