I currently have a Chevy cobalt with the stock battery in the back not under the hood and a batcap2000 back there too. i have an extra optima redtop laying around and i"m wondering if it would be alright to add it in there as another battery or if mixing batteries like that is not recommended. --If is is alright to run it parallel is there a specific order the batcap and the optima would be in? Thank you