A number of Land Rover owners who have purchased the Priority Start have asked for a diagram on connecting to a Dual Battery Setup. It is very straightforward. See the attached pic and instructions.
Parallel Dual Battery Installation.
On dual battery vehicles, only one PriorityStart unit is required. Please make sure the batteries are in "Parallel" (i.e., two 12-volt batteries cabled together from positive to positive, and negative to negative).
Important Note: The cable connecting both batteries ("Direct Cable between Battery 1 To Battery 2") must remain separate from the cable deriving from the starter. If one cable is used, it must be separated into two. The cable (connecting both batteries) should not be moved to the top post of the Priority Start! It should stay on the actual posts of both batteries.
The Priority Start can handle up to 1000 starting amps. (Amps that the starter draws).
Very important to follow this note: Individual accessories that have separate wiring will also be moved to the top of the Priority Start unit.
Remember the Priority Start is now monitoring everything through the cable and so would pick up everything attached to it.
Link to the Priority Start Unit.