Deep Cycle Batteries

I have a Optima Yellow Top Battery in my ride and want to add another in the rear.  Do I just have to run a Pos. & Neg. wire from the front one to the back one?

Yes you wire it that way, but unless you bought them at the same time and they are the same age I wouldn't do so without an isolator. I just did an install with 2 batteries that were the same age and I still used an isolator. In case you don't know what the isolator does, it basically makes it so that the back one is the only one being used when your vehicle is off. While the vehicle is running they are both being used and both being charged by your alternator. Make sure as well that your alternator is beefy enough for both batteries and that you use large enough cables to run to the rear battery. You would probably need to go with 1/0, and make sure the wire is fused in the front. I ran the cables under the vehicle and up throught the floor pan in the rear. Good Luck!!

I have seen many people run dual batteries with no isolator and never have any problems.  I have also heard of people using isolators and the second battery not getting fully charged.  Any one else ever hear of this?