Ford GT battery.
Gentlemen,
Almost 2 years ago while doing some work on my FGT, I left the keys in the ignition with the ignition turned forward to the accessory position. Three weeks later when I returned to the car, it was deader than a door nail. There wasn't so much as a single electron left inside my factory Optima battery. Per the advice I received on this forum I assume that the battery was toast so I went out and bought a brand-new one. Before purchasing a red top Optima from my local Batteries Plus+ shop, I stopped in to Ford of North Scottsdale to see how much more they would charge to get me the Optima with the Ford GT logo on the top. Amazingly, the factory FGT Optima, complete with logo, was not only about 10% cheaper than the price at Batteries Plus, my Ford dealer had it in stock!!! I bought it on the spot of course and took it home. Before installing it I thought I would at least try to recharge the dead battery already in my car. I put it on a two amp slow charge for three days. The car started right up and that battery has performed flawlessly for almost 2 years now since that event. My brand-new FGT Optima battery has been on a battery tender in my storage room for the last two years.
Based upon this I would at least try to recharge your dead Red Top Optima before throwing it out. All the best.
Chip