I have a red top optima, purchased last july. I love the starting power that this thing has but I have concern. That concern is that this battery doesnt seem to hold a charge well. I can have it fully charged disconnected and a week later it is down to 10 volts and cant crank my 454. Maybe I am being picky but I thought these optimas were supposed hold a charge for a very long time. Has anyone else experienced these problems?