From my understanding (researching near 20 yr old posts)
to relocate the battery to the trunk (directly behind backseats, next to the rear passenger strut tower) of my ef sedan SAFELY, I will need to: Run 0-2g wire from the positive terminal to the starter motor, and a seperate 2-4g wire to the main fuse box? Do both wires need a fuse, or just one. If just one, which wire to where? What amp rating is safe for the fuse? Does the wire that goes to the alternator, also need replaced with a bigger one? Any sensible answers appreciated.

 

I'm in for this as well. I've had this wired up for more than a decade now and I need to find out, too. Here's my current setup but I do not know the value of the necessary fuse. I hope this visual aids in the response.