"I recently replaced my battery, and thought I had it installed tightly. I didn't. With my 'normal' Fiero style of driving (fun and fast), my battery slipped over against the pulley, whick cut a nice cresent shaped hole into the bottom end cell, and drained the juice!"
First, use any method to keep the cell wet, including a big bucket which will hold the whole battery, fill with WATER. Keep the cell wet, do NOT allow to dry.
Second, hook up a headlight or two and let the battery fully discharge.
Third, fix hole. There's stuff to do this at Auto stores, likely WalMarts, Targets, etc. It is a ribboned epoxy type of stuff, like tank/radiator ribbon sealer, etc. Also silicons will work, I'd recommend Permatex Ultra Blue. Roughen the area to be fixed with coarse sandpaper. Spoog alot into the hole and force some through with a plastic knife or something, then continue to fill the hole. Do it all in one step.
Fourth, fill that cell with water, only barely to the top of the plates of the cell. Charge with a tiny charger, 1 amp or so, 2 ok. 8-12 hours.
Last step is adjusting concentration. Got a hydrometer, right. Use the good cells as a guide to where the bad cell should be. It will be weaker. Since there's not much in that cell yet, you'll need to tip the battery to get a sample. You may add straight acid to the bad cell to bring it up to the others. Or if you're cheap canablize the acid from the other cells and replace with water, or nothing - the levels need not be any higher than the top edge of the plates. Pure acid may be needed to get the cell all the way up. You can buy it aat most parts stores for $5 range.
Done right, the battery will be 95+% of original. Why the discharge cycle? The battery was likely at 80-85% charge when drained. To simply fix the hole and refill with acid would result in over concentration, just as bad as too weak. We've a chemical balance here.
From: Clark