Hey guys I have 2 sa12's and and running off of a sax 1200d and plan on jumping to the saz 2500d. I have a yellow top optima under the hood now and I have an xs power 3400 on it's way, I have heard it's not good to mix batteries but I really don't want my optima to go to waste, I just bought it like 2 weeks ago. If it's ok to mix both will go under the hood, which one should go to the amps...