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Old May 19th, 2017, 04:30   #1
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Join Date: Jun 2016
Location: Marquette, MI
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Default S177 Fuse Blown

So I'm kind of in a pinch. My fuse for my 90 amp alternator blew up yesterday and I don't know what to do. I need my car today in a few hours. Do any auto parts stores carry a fuse like that? Do I need a 90 amp fuse or a higher amp? I can't read what the old one says because its all burnt. How fast can I get my car driving again?
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Old May 19th, 2017, 07:04   #2
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You need to replace the whole fuse box and the alternator cable. Do a search on here. Common problem
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Old May 19th, 2017, 08:00   #3
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in areal pinch I would consider using some copper wire that's rated at 90 amps via electrical code.
I actually have some heavy gauge copper, like the power lines going down the road, and I would pull out a strand and either single it or double it to meet the same volume of metal as the 90 amp fuse.

This is not the safest! It is far safer than bringing the wire across and leaving out a protective device at all!

I actually had an issue in an old Dodge truck I had and ended up twisting a single strand across the burnt out element. I never had any issues with it and tried another fuse as well; the truck wouldn't start without that circuit, otherwise, I would likely not have tried it in the first place.

That being said, fuses are generally rated at for maximum circuit potential (startup energy rating) and if the fuse has blown then there is likely another issue causing it.

Runonbeer is usually correct and I would follow his direction.

Any modification of the electrical circuit over current protection has risk, limiting that risk is important and never do it if you're in any way uncomfortable with the possibilities.

I always use a single strand wire that is comparable, maybe 5% more potential than the original conductor, when modifying a circuit for temporary or permanent use!

We must always remember that any and all modifications we do are done at our own risk!

Not that you don't know that already.

stealership is probably holding one right now though too.
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Old May 19th, 2017, 09:13   #4
Join Date: May 2004
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Fuses are devices designed to protect electric circuits. When a fuse blows it often indicates a component is drawing too much power because it's broke or shorted to ground.
I would not put a penny in the fuse, if it's a huge draw causing the fuse to blow, you could have a fire.
That being said, often those things on top of the battery sometimes corrode to ground, meaning you can just clean up the mess and drive on. Replacing the whole fuse box set-up is often the best solution as the corroding will trash the contacts.
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Old May 19th, 2017, 09:27   #5
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Location: Kansas City Missouri
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Post number two is probably right. Cable develops resistance where it meets fuse box. Resistance makes heat and the fuse box burns or melts or maybe if caught early might just have minor cosmetic damage. Fuse is damaged in the meantime.

If your so desperate order parts overnight, rent or borrow a car.
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Old May 19th, 2017, 09:30   #6
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Note also that fuses are thermal devices - the excess current heats the link, it melts, and the circuit disconnects. Bad connections to the fuse holder can also produce extreme heat (hence the melted fuse box) and that heat can conduct to the fuse and cause it to open well under it's rated current. Look carefully at the overall situation and evaluate based on what you see . . . if all else looks good, and the fuse is drastcally blown open, it's almost certain there was a fault. If there is evidence of a lot of heat, then it may just be a high resistance connection producing it. And lastly, if the fuse failure is pretty clean (small crack in the link, not much black,etc.) it's possible that the failure may also have a factor of vibration/metal fatigue . . .

Last edited by tadawson; May 19th, 2017 at 23:40.
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Old May 19th, 2017, 09:45   #7
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Solved, some guy in my local group saved me and had one laying around. Also, the fuse blown was due to loose connection and it was not drastically blown open. Looks like the connection had corrosion on it too.
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Old May 19th, 2017, 19:45   #8
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Glad you got it fixed. For future reference audio installers that install big amplifiers usually have the bigger high amp fuses.
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