Wiring help for the "Big 3"

[frojoe]

I'm in the middle of a pretty large stereo install, so before I put the large gauge wire back to the trunk I was going to do the big three upgrade (Battery negative ground, Alternator to battery positive, and engine ground). I'm all set on the two grounds, but I have a few questions about the wire going from the alternator to the battery. I've read that you can just add new wires in addition to the factory ones, but the factory wiring doesn't seem to go straight from the alt. to the battery. Is it ok to just run a new wire, and if it is what size fuse should I use? I was thinking 80 or 100 A because the alt. is 70 A. Also, There are a few different wires coming out of the alternator, so I can't tell exactly where to attach the new wire. I have been looking at the wiring diagram in the official Camry repair manual (on page 3 of the section on the charging system), but I really can't understand it. Thanks for any help.

For anyone interested the system is:
-Alpine CDA-9883 HU, used w/ ipod
-Alpine type-R 6.5's in the front
-Alpine type-R 6x9's in the back
-Alpine type-R 12" sub, 4 ohm dvc
-Alpine MRP-M450 400 W mono amp at 2 ohms
-Alpine MRP-F250 40x4 amp
-tsunami duel amp wiring kit with 1 farad cap.

I'm not really sure why I went for all Alpine, I have just had a lot of luck with their products that I have purchased so far, and I like the look of them because they are all housed in custom fiberglass enclosures in plain sight. I wish I had bought component speakers for the front, I'm not sure what I was thinking. I'll post up some pics once everything is done.

[frojoe]

well after digging around the alt. for a while I figured out which wire was the big one, so I will use that to the battery. The only question I still have is what sized fuse to use. The alt. is rated at 70 A at 12v. Right now I am planning on using an 80 A fuse, but I could use a 70 instead. Should I use the 70 or 80? Thanks.

[Jeeves]

Fuses are often rated for 125% of normal load.