Outer Limits 4x4 Board

Hey all,

I just wondering what ways are easiest ways to install a dual batteries system
from what i have heard
Some people use solenoids which through which it will determine to chrge the 2nd battery or not
While others just have a gauge in there dash to tell them there batteries charge and use a relay and switch to determine when to enguage/disenage the batterie?

Not sure if what i have just said is correct but any help would be appreciated, and dose anyone know the cost or doing something like this?

Have a search in the auto electrical section. There's a post discussing some of this info now and a search will reveal heaps of posts about this topic.