I have a stock battery thats is only about 9 months old and its fine, but i was looking into a deep cycle battery because i like to listen to music or watch dvds in my car with it off. Would i be better getting a yellow top and using it as the starter and for everything or getting 2 batteries. and how would i go about wiring up the two batteries so the car starts off the stock one, and then the system runs off the other one?