So i'm in the market for a new battery for my rex, and have been looking into the PC680MJT by odyssey. but the problem is, i live in phoenix... where it regularly gets hotter than 115degrees. has anyone owned a 680 in such temperatures? would i be better off getting an optima battery? the car doesn't have a/c, a radio, or much else for that matter, so i wont be placing large demands on it, but i would like to know how well it would hold up to the heat here. any suggestions?