sorry, yeah im confused on that statement.
the power magic pro, is to allow you keep using the stock OEM car battery after the car is shut off. it is designed to activate when you hook up a switched power source. that way it knows when to turn on.
there is also a none switched power lead that needs to be hooked up.
the amount of time that the unit runs depends on OEM battery capacity.
im using couple of blackvue lithium batteries. power magic ultra batteries. you can link more of these together for longer run time.
its really all magic from here.