There are a number of options when considering the dual battery set up. At Nomad we try and give you the most simple set up to the hardcore , hardwired options. Take a look at DCDC simplified youtube info tutorial
The easiest DC set up we offer is utilizing your existing vehicle ciga socket, where you plug the ciga plug of the DC into the socket of your vehicle up to 10amp DCDC option only, because your vehicle ciga socket ll be a 10-20amp rated, We offer a 5 or 10amp option, just plug in and go (please note check the rating of your ciga socket to ensure your load is less than the spec on the socket.
When you are considering a full dual battery set up , remember the options now are a DCDC with Solar input and built in VSR (voltage sensitive relay) a VSR simply prevents the second battery set up from flattening the crank or main battery. You connect the crank to VSR to DC then auxiliary or second (dual battery) iView online Tutorial