the alum experiment did not work. with a fully charged battery it wasn"t even enough to get the starter to engage. don"t waste your time on it. soundguy"s epsom may work but that battery is going to the store for a core return. i had 12.75 volts on it too but it drops 1/100th every 4 or 5 secs.
maybe this battery had something wrong internally, plate or whatever, that prevented it from working. other batteries may differ.