Battery alchemy?

And as far as the acid thing goes, the water evaporates (or boils) out of the acid, increasing the acidic 'concentration', if you will.

The hydrometer measures this concentration, which is actually more correctly called specific gravity (which simply rates the density of the acid compared to pure water.

The acid only goes away when the cell is discharged. Add distilled water to restore the fluid level, charge to restore the acidity. Charging literally converts it back to acid.

A shorted cell is doa. I've literally pulled in the driveway, ran inside, ran back out, and the starter wouldn't do a thing. The tricky thing about shorted cells, the battery might have enough juice to light all the lights, radio, etc. ... but smack it with a load and the voltage drops like Chevy dumping the hummer during a gas crisis. Usually four to five volts or less when hitting the starter tells you a cell dropped.

The last half dozen batteries I've replaced have died in such a fashion.

My dad has has amazing luck with optima, but he's the only one I know running them. His has lasted eight or nine years