Seperate Battery

I have a COMP SVR Deep Cycle battery I want to throw in my trunk and hook it up to my system. How would I go about doing this. Can I just throw it in and run the neg and positive fused to the amp or do I have to connect it to the main battery or alt? Just curious. And also, If I wanted to give my amp 17v how would I go about doing that. Any help is appriciated.