is there a wiring diagram for a dual battery set up for my 2007 newbody crewcab sierra?

 

Check out the durmax it comes with 2 batteries

 

what do you mean by a wiring diagram?? You just hook them up in parallel. If they are not the same battery you may want to put an isolator between them.

 

Yeah if you don't run parallel and instead run negative to positive you will actually create a 24 volt system which will fry alot of things. so make sure you hook up correctly. Did yours come stock with two or are you adding one like i did?

 

i believe it is---series, makes it 24 volts, but same amps
parallel, same voltage, double the amps(assuming identical batts)

 

Yea, things in series see the same current, but add voltages. Things in parallel see the same voltage, but add current.