Adding a 2nd battery to your cars existing electrical system is quite simple.  If you have one of the two relays mentioned follow the four steps below.  I recommend the Stinger Red or Yellow top batteries.  I carry all the other parts needed as well.  You'll of course need power wire, fusing and terminals to complete the task.

SGP38 / SGP32 / SR80 / SR200 Installation Instructions

Two Large Terminals:

1 Connect one large terminal to the vehicle's main battery via a fuse holder

2 Connect the other large terminal to the sound system's auxiliary battery batteries, again, via a fuse holder. Note: The large terminals can be wired in either direction

Two Small Terminals:

1 Connect one small terminal to true ignition power from your ignition harness. True ignition will keep power through the cranking cycle of the starter when tested. Verify that your power source is true ignition.

2 Connect to chassis ground. Note The small terminals can be wired in either direction

You can find all the parts on our website also.