The Big 2?

[srt4100 10+ year member]

Well yesterday I decided to do the Big 3. Once I looked under the hood I noticed a few things ive never seen before. Well the positive battery connection had 2 wires running to it. 1 to the fuse box, and 1 to somewhere way down behind the engine, with a black wire spliced into it running to the alt. For the negative there were 2 wires also, 1 to somewhere down the engine also, and 1 connected about 5 inches to some metal. I upgraded the Alt wire to positive to 0 guage, and the negative to that metal with 0 guage. I have no idea where to put the last part of the big 3. Engine to chassis. Where is that wire?

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[dman4486 5,000+ posts]

use the mounting bolt for the alt and run it to the frame/chassis

 

[srt4100 10+ year member]

Just any mounting bolt on the alt? To anywhere on the chassis? Also anyone with some pics of what I need to do will be great. Also, what are the 2 wires running behind the engine for?

 

[dman4486 5,000+ posts]

Just any mounting bolt on the alt? To anywhere on the chassis? Also anyone with some pics of what I need to do will be great. Also, what are the 2 wires running behind the engine for?

one of the large bolts that hold the alt to the block.

one of the wires should run to the starter(the one you couldn't trace) and the other is for powering the rest of the car.

for grounding, the battery should already have a wire to the block and a wire to chassis, but the point of the big 3 is to just ADD wire to allow for more current. Don't remove the factory wire.

 

[srt4100 10+ year member]

ok thanks. The only wire I took out was the wire from the alt spliced to the starter wire. and I just trimmed the starter wire and put it together with the fuse box wire, butted to 0 guage from the battery. I guess I just have to do the alt bracket to the chassis somewhere. Would that ground connection to that metal be ok?

 

[dman4486 5,000+ posts]

ok thanks. The only wire I took out was the wire from the alt spliced to the starter wire. and I just trimmed the starter wire and put it together with the fuse box wire, butted to 0 guage from the battery. I guess I just have to do the alt bracket to the chassis somewhere. Would that ground connection to that metal be ok?

the ground for the battery and the ground for the alt must be to a substantial piece of metal.....I actually used the same bolt on the FRAME for both.

 

[srt4100 10+ year member]

Ok. Well I have read and I want to fuse the alternator to the battery + connection. Im pretty sure my mustang has a 130 amp alternator. What size fuse would I need? Because I dont want a fire or anything to mess up. Im starting to regret doing the big 3

 

[SPL Blazer 10+ year member]

You can go with a 300 amp fuse. Your fusing the wire and since 0 ga can handle a decent amount of current you want to fuse it accordingly. If you have a 130 amp alt you don't want to drop in a 130 amp fuse, you want to use the largest one for the size wire your using. I used to have a 300 amp fuse on that wire, but dropped it.

 

[DidUHearThat? 10+ year member]

It depends. You want the fuse to be less than the maximum rating for the wire. 1 gauge is not the same as 0 gauge, most people and companies mix these up. Sometimes on purpose to decive customers. Usually when you see "0" gauge it's really 1 gauge. Which still plenty for most uses.

1 gauge is good up to a max of 250 amps, 0 gauge is good up to 325 amps.

Depending on how much power you need for your amps I would choose the smallest size fuse that will accomodate your amps. Add up you amplifier fuse ratings and use that number to pick your fuse size, as long as it is less than the max rating of the wire.

 

[srt4100 10+ year member]

Amp pulls 75 amps. Would a 150 amp fuse be good for in between the alt and battery + connection? Alt can only put out 130 max. I just want to be safe and have no fire or anything like that. Also, since I cut some stock wires and redid some stuff, would that void my warranty?

 

[SPL Blazer 10+ year member]

It depends. You want the fuse to be less than the maximum rating for the wire. 1 gauge is not the same as 0 gauge, most people and companies mix these up. Sometimes on purpose to decive customers. Usually when you see "0" gauge it's really 1 gauge. Which still plenty for most uses.
1 gauge is good up to a max of 250 amps, 0 gauge is good up to 325 amps.

Depending on how much power you need for your amps I would choose the smallest size fuse that will accomodate your amps. Add up you amplifier fuse ratings and use that number to pick your fuse size, as long as it is less than the max rating of the wire.

That sounds good if your fusing a wire going to your amps, but he's talking about fusing the wire from the alt to the battery. I regularly run over 400 amps through a single run of 0 ga and never have a problem, and others I know run over 1000 amps through a single run of 0 gauge wire and all without failure of the wire. So the ratings you listed might depend on the amount of time the wire is subjected to high amperage flow.

 

[DidUHearThat? 10+ year member]

150 amp would be fine.

 

[SPL Blazer 10+ year member]

. Also, since I cut some stock wires and redid some stuff, would that void my warranty?

thats for your dealership to say, but only if they see it.

 

[srt4100 10+ year member]

Ya im thinkin if somethin ever happens where I need to take it in I can redo what I cut. The wires will still reach the positive terminal and they had the alt wire running into the starter wire with it covered up. I can get the old wire and do what they did and they shouldnt be able to tell. Sound good? Also, so the 150 amp fuse will be good for sure between the alt and batt?

 

[DidUHearThat? 10+ year member]

That sounds good if your fusing a wire going to your amps, but he's talking about fusing the wire from the alt to the battery. I regularly run over 400 amps through a single run of 0 ga and never have a problem, and others I know run over 1000 amps through a single run of 0 gauge wire and all without failure of the wire. So the ratings you listed might depend on the amount of time the wire is subjected to high amperage flow.

??? Those are not good engineering practices, certianly not something to recommend to a beginner.

Even if 400 - 1000 amps did not cause a failure in the wire, if they are more than about 2 feet long you will experience voltage drop. The wire ratings I listed are the commonly accepted norms. Fuses will actually pass significatly more current than thier ratings for very short periods without popping.

He has a 130 amp alternator and only needs 75 amps for his audio. 150 amp fuse is fine.