The result is a little suprizing as a bad cell will usually not take the alternator voltage all the way down with it. In other words with the engine running it will usually manage to get the voltage up to 13 or 14 v anyway. Must have been REALLY shorted, ie, unusual hard shorted condition. Glad to see that you found it, in any case.

The guy at the shop said it was the first Optima he'd ever seen fail. Surprised me as well. I was sure that the alt. was shot.

A happy ending...agreed, it is rare to get a bad optima. "Stuff Happens". I recall a non running lawn mower once. Took me hours to figure out that a brand new spark plug was bad...put the old plug back in...vroom.