SavageX28

And the big 3 is a - from the battery to the chassis, and a - to the alt and the a + to the alt?

So just run a positive from the battery to the other and just ground the one in the trunk out?

I'm trying to find out exactly what I need to do in order to run a 2nd battery, I'm 16 and just starting out and trying to learn how to do these things. Right now I've got 4 American Bass 400w max 10's on a 1500w spl amp and I'm noticing headlight dimming and pretty soon I'm planning on doing a build so help would be greatly appreciated.