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What size fuse for alternator power wire


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1 more post for the road:)

Just fuse it for whatever the alt is rated for. If you have a 140 alt put a 140amp fuse on it. PERIOD

this is not true. period.
i know it's not exactly true. I'm just being sarcastic because this topic should be over. PERIOD

you are part of the problem

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Correct me if I am wrong but we are talking about the cable that goes from the alt to the battery that is in the back of the car. There is no battery in the front. The batteries in the back have a separate fuse. Correct?

If the cable gets pinched in the middle then the short will be energized from both ends to the short. The battery will start dumping power into it. The battery fuse will blow because it can supply the 250a to blow it. The alt also is dumping power into the short. If the alt can only supply 140a and the fuse is 250a then it won't blow because there is not enough power to blow it. Normally the fuse would be what the wire is rated for if . What we are doing here is not normal. Part of the confusion is that the 1/0 is bigger than what is needed as Strange Duck stated. The 1/0 will work but we have to take all things into consideration.

1/0 needed vs. wanted are two different things. This isn't a stock electrical setup. Having drop of 1-1.5v across a circuit as would be in stock limitations is really not desirable. Imagine you have a drop of 1.5v between your alternator and battery. You could be charging to 14v but still be discharging your battery at 12.5v. It'll hinder it's ability to recharge. While it may not be "needed" for safe operation of the equipment, it's certainly desirable from a performance standpoint

As to the fuse issue... You can't use a fuse that will blow in the event of an alternator short circuit scenario but stay intact during normal day to day beatings. It doesn't exist. The reason you don't need to fuse the wire near the alt is because the second you turn the key off, there's no more flow of power. Problem solved. That's not the case with a battery, and hence why it needs to be fused

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Ok then don't fuse the alt. Make sure you turn the key off when you crash.

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Most modern cars cut the power automatically in a crash.

Should still be fused though.

That being said a lot of people's definition of "music" is a clipped 30 hz sine wave with some 80 IQ knuckle head grunting about committing crimes and his genitals.

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