Battery is in the trunk so that would require running power from the front of the car to the rear. NO thanks

You would think there would be a jump wire feature circuit breaker

I am pretty sure I have never seen one in my 35 years as an electronics engineer but then again my memory is failing... LOL.... If you have a short you can't pass current to only the circuits that aren't shorted. At least not without a bunch of circuitry and intelligence. Sure won't cost $10 and would still require the separate wires that you don't want to run in the first place...

The idea above with the Ford starter relay is a good one.

Don

You are splitting hairs. If the circuit breaker trips, you likely saved you car. You can probably handle resetting your clock radio. :lol:

LOL. One time when i was 16 being summer baseball my clock reset because my battery died. I would go to the field and wonder why no one showed up after a long drive. Normally i would wait a hr and then leave. 3 days past before someone came to my house wondering why i missed 3 baseball games. They thought i quit. my clock was 2 hrs off hahahaha. Thinking back now i would have smacked my 16 year old self for leaving my house driving 2 hrs to the field and someone time didn't change

OMG Randy , maybe edit that out and not tell us that your young self did that ....lol

I've been running the breaker Greg recommended above for a while now. It is nice to be able to just trip it to disconnect power when needed instead of removing the terminal. There is a ton of opinion on which way to go and which way is best. I don't think you can go wrong with either the breaker or a Ford type solenoid. I went with the breaker after seeing what the factory did with the G8 rear mounted battery. It has power all the time running the length of the car with 2 additional fused circuits right off the positive terminal for other electronics.

Fuse
 

A fuse is the fastest acting protective device in any case. A breaker has the convenience of being resettable but won't open as fast as a fuse will.
Put a disconnect switch at the battery and a main fuse after. The main fuse should be sized based on the size of your wire or cable. I keep a spare fuse in the car. The purpose of any protective device is to protect the WIRE. You can take an inline fuse holder with a 5 amp fuse and connect it across your main switch terminals. This will give you memory power for your electronics. When the main switch is in the open position the power will travel through the "memory" fuse. Just remember that fuse is in there if you want to remove power completely to the system for service. If you forget to turn the main switch on and try to use anything with an amp draw over 5 amps the memory fuse will blow. Also handy for anti theft as you can kill the main power but still have power for an alarm. If the thief gets in they won't be able to crank unless they find your main switch.

^^^. I did exactly what TerryD stated.

One time I forgot to switch on the main breaker, and promptly blew the 5 amp fuse when I hit the starter.

Only once? I keep a bunch of these fused in the car just for this reason. :)