big 3

I didn't use a fuse in my alt to battery positive run...you will not need a fuse if you run the wire in a safe route...double loom it and tape it up. If you keep the wire away from moving parts and high heat than you are fine without fusing it.

Lets think about this. Here you are upgrading the electrical to make the transfer of current as efficient as possible. This means that you are going to be taxing the alternator to the extreme's. This means that the alternator is going to be getting uber hot. I guess that in a perfect world there is never a case of a alternator failing due to heat and shorting out (which of course is now connected to the battery and not fused). Maybe the built in voltage regulator is going to pack it in, who knows, my crystal ball does not show me if and when a problem may happen in your car. Be smart, fuse the line.Top Secret, I can tell you but then my wife will kill me.

Or another way to look at it might be this way: ANY power cable directly connected to the battery should be fused for that power cable's safe maximum rating. Simple as that, and forever the safest way. How about this way: Whether employed normally as an "in" cable (charge) or "out" cable (power), if the insulation is somehow compromised, it will INSTANTLY become an OUT! It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."