I have two batterys and it makes my starter drag it will start but it cranks really slow. Why would it do that two optima blue tops brand new and they are hooked up + to + And - 2- all stock wiring is hooked up on main and all rest is on 2nd one. I was told I need a better altinator. Help please

 

did you use an isolator?
if not, you are no further ahead. both batteries will drain at the same rate, leaving you with two dead batteries.

bleepin jeep has a couple vids to show what you need to do.

and look up how to run batteries in parallel (like you did) or in series. there are dangers you need to avoid. that's where the dual battery isolator set up comes in handy.