In reply to Hasbro:
I have used a 680 in my race car for abut 3 seasons now.
I think the Ultimizer charger is a key to long battery life as it periodically cycles the battery charge to peak and that helps reduce the tendency for sulfating (undercharging) or overheating (overcharging) that occurs when no supplemental charging is done or a cheap "trickle" charger is used. As far as I can tell the Ultimizer handles itself and the battery pretty well when connected to the battery while the battery is connected to the vehicle and its normal "Off" loads.
According to the Odyssey literature you are within the acceptable operating and storage temps for the battery. However it notes the storage life duration between charges is halved between abut 75 and about 100 degrees (2 years to 1 year).
I think, that despite me taking as many precautions with my battery to keep it properly charged as possible and cool (it is mounted inside the cabin rather than in the engine compartment) that its cranking capability has dropped some, and it is especially noticeable then things are hot - I frequency cannot turn over the engine in my car with the 680 right after completing a run that usually involves 1-2 starts during staging, about 10 minutes of engine operation including about 3 at high RPM and a minute or 2 cool down. If I let it sit 10-20 minutes or so giving both the engine and battery a chance to cool some it will restart.