With my current setup, my battery somewhat takes a beating. I can see the headlights dim sometimes, and often I see other interior lights dim when im pounding my subs. What would I need to do when I add my second amp and third sub to prevent the battery from not getting enough power? Someone mentioned a capacitor? Whats that do? Also, I heard putting a second battery in the trunk? How would I manage that so it would re-charge? Any help appreciated.