What size fuse for big 3?

[da12b 10+ year member]

you really dont need a fuse on a 90amp alternator using 4ga i mean its even optional but recomended if you use 1/0ga so if your using 4ga you dont need to fuse it. Only if you want to. Read the Big three article

A fuse is needed between the battery pos and the alternator. If you follow the OEM cable from the battery to the alt, you will find that it is connected to the fuse box. The fuse is to protect the alt and the wire from getting fried. When adding on the pos battery to the alt, I would suggest a 4 ga. or a 1/0 ga cable. You should use a max fuse rating of 150 ampere for the 4 ga, and a 300 ampere for the 1/0 ga.

All alternators are able to produce more then 14.4 volts, but the regulator regulates the voltage so the internal parts does not fail. If this regulator fails and there is no fuse, excessive amperge will be going to the battery and cause the battery to boil the water in the battery to the point which it will explode. Not a happy sight.

Now, do you think the fuse is important, if not, well I say "Get the marshmallows out, if it happens.":yumyum: ...lol

 

[klepto 10+ year member]

I know its been posted in here before, but i cant find it. Where is a site where i can find the output of my Alt? I drive a 2003 ford focus SVT.

 

[Ruffy 10+ year member]

130 amp alternator? use 1/0-2 gauge and put a fuse of 150-180

The wire can sustain more than the fuse. The point of the fuse is to blow if the amperage gets to be too much instead of the wire burning up

Now I'm kindof at a wtf point for my setup. My sub amp has 2 80amp fuses, and its currently running off 5ga scosche wire(Will be upgrading soon, already put my order in)

Get this. The biggest mini anl fuse i have is..... 80a!

Already ordered 2ga, 4ga wire, and 100-200a fuses all around

 

[Ruffy 10+ year member]

A fuse is needed between the battery pos and the alternator. If you follow the OEM cable from the battery to the alt, you will find that it is connected to the fuse box. The fuse is to protect the alt and the wire from getting fried. When adding on the pos battery to the alt, I would suggest a 4 ga. or a 1/0 ga cable. You should use a max fuse rating of 150 ampere for the 4 ga, and a 300 ampere for the 1/0 ga.
All alternators are able to produce more then 14.4 volts, but the regulator regulates the voltage so the internal parts does not fail. If this regulator fails and there is no fuse, excessive amperge will be going to the battery and cause the battery to boil the water in the battery to the point which it will explode. Not a happy sight.

Now, do you think the fuse is important, if not, well I say "Get the marshmallows out, if it happens.":yumyum: ...lol

Using the "max" fuse rating for the wire is not reccomended nor is it smart. You want the fuse to blow well before the wire goes. if a wire starts to die at 300 amps and the fuse is a slow burn at 300 you could damage something.