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fusuble link replacment by johnguzman1212
Started on: 05-27-2015 08:53 AM
Replies: 3 (118 views)
Last post by: thesameguy on 05-27-2015 03:03 PM
johnguzman1212
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Report this Post05-27-2015 08:53 AM Click Here to See the Profile for johnguzman1212Click Here to Email johnguzman1212Send a Private Message to johnguzman1212Edit/Delete MessageReply w/QuoteDirect Link to This Post
I just finished a 3800sc swap and my link was discarded. Ive heard to place a maxi fuse between the alternator...what size do i use?
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Gall757
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Report this Post05-27-2015 12:57 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
See the Ogre's cave......delinking.

http://home.comcast.net/~fierocave/ecmwire.htm
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theogre
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Report this Post05-27-2015 01:07 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
Who knows? Not enough data to say.
First problem is Alt max/peak Amp output, Alt output Wire Size, etc can affect the fuse or fusible link choices.
Too low fuse can have "false"/"nuisance" blows. Nothing wrong but the wrong fuse.
Too big fuse can have a fuse refuse to blow and then the main wire will heat fast often causing a fire.
Both that can happen on the highway.

Using OE harness but what alt and what's eating that power? Bigger amp alt might need to replace OE wire because can't handle extra power.

Second is Link/Fuse is not really there to protect the Alt etc. Is to stop the battery from dumping 200+ amps to a short circuit. That's why most fusible links are near/at the battery + terminal on any vehicle.

There are easy rules to correctly size links to wire to protect. Very short... Link is smaller gauge vs wire to protect and about 6-9 inches long.

As for "Fuse Links are Bad" myth? Billions of vehicles have Fusible links and never have problems.
Some love to replace links w/ maxifuse. They most likely are not qualified to say fuses are good plan or what amp value to meet demands on a given circuit and wires use by the cuircuit.

Max Fuse may be "better" or not depending on the application... Many cars w/ Maxi Fuses still have Fusible links too. Links are "last line of defense" from battery melting down the wire harness. Others w/o links have Maxi's and others very close to the battery.

Very few Real Experts and Engineers replace fusible link with any type of fuses or breakers for safety and liability reasons. Fusible links are still use worldwide in many applications including automotive. Fuse makers like LittleFuse and Others won't give you data because they Cannot tell you what Maxi fuse can safely replace Fusible links.

Properly installed Fusible Links rarely cause a problem. Plus Water Resistance is easier and needed because Fiero power dist "box" is in a very wet area. Most Maxi and other Fuses hates water and need a waterproof socket and cover for use in Fiero engine bay.

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thesameguy
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Report this Post05-27-2015 03:03 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Do NOT use a Maxi fuse. Maxi fuses are not rated for those types of amperages. The correct part is an Mega fuse, and they're available from 40a to 500a. Mega fuses have superior heat dissipation and survive transients better than Maxi fuses, and their connection is a lot more suitable to high amperages with less resistance. Littelfuse publishes a guide to Mega fuse sizing, but generally speaking +50% is their guideline. A 75a alternator would have a 125a fuse, a 130a alternator would have a 175a or 200a fuse. As Ogre said, the fuse is there to protect the electrical system in the event the alternator shorts and dumps the battery to ground, so *really* any fuse in excess of the alternator amperage and less than battery capacity will do the job. You just want a narrow margin so the fuse will act faster and account for a depleted battery. The +50% padding is there to account for occasional amperage spikes that do happen.

Mega fuses should be placed as close to the battery as possible. For a small alternator like a Fiero you can use 8ga wire, but higher amp alts want 6ga wire. I typically just use 6ga wire because that's what I have. You can buy Mega fuse holders in several configurations and you can sometimes steal them off production cars in junkyards. IIRC, the oval Ford Taurus has a pretty accessible one.

[This message has been edited by thesameguy (edited 05-27-2015).]

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