Good question I believe that this question has been asked before I am not sure but I believe that you have to charge it in series with another 6 volt battery . I hope that some one with a definitive answer can help ,but it's a good thing you are checking before you mess up your optima battery.
I've never owned an Optima, but have heard of having to charge them in parallel with another 6 volt battery.
My lead/acid battery can set untouched for 6 months of winter and start the car fine in the spring.
Man.........who in their right mind would live where there's 6 months of winter?![]()