Tiny,
I recently had the similar scary problem after I accidentally completely discharged a 5 year old 6v Optima. I do not know the details, by my cheap, new, and not very powerful chargers have some sort of feedback mechanism (probably to keep them from tripping-out). My friend with a very old and powerful non-electronic charger (his family own an old and successful used-parts yard) was easily able to put a charge back into the battery. It still rates-out as good as new.
I think the
Optima 6V Battery is rated at 800 CCA and 1000 CCA (however, I often see it listed by sellers at 850 CCA).
Tim
