General Fusible Link Question

[harkauto]

I have an old 1990 Dodge Spirit V6 and the other day when putting the battery back in the car after a recharge I accidently crossed the negative and positive wires on the battery terminals.
Needless to say the fusible link that is located in the Positive battery cable that goes to the alternator did its job nicely and sizzled and smoked and broke the current before my goof-up did any harm to the system.
Problem now is...I cannot find a replacement fusible link anywhere. I have tried all of the autoparts outlets and even the Dodge dealerships here in town and no one has a fusible link that I can use.
I told my buddy about my situation and he informed me that a fusible link is simply braided wire of a lighter gauge soldered between the heavier gauge wire within the cable that acts as a fuse for the heavier wire in the event of a circuit overload of some kind or in this case to protect the alternator and electrical system against dipstick car owners like me that decide to cross battery terminal wires.
Since I cannot seem to find a replacement fusible link, my buddy told me to simply find some braided wire that is the same gauge as the lighter fusible link wire that burned through when protecting the heavier wire in the system. Then simply cut out the old link and solder in the new wire, making sure the wire has a fire retardant rubber sheathing.
He said in essence this is a simple way of replacing a fusible link.

I just wanted to run this by someone else for a second opinion.

I appreciate your wisdom.

Thanks!

Harkauto

[jd585]

can't you get an inline fuse holder and place the right fuse in it and join the wires together with connectors-- would think any spare parts place would have one

[harkauto]

Originally Posted by jd585

can't you get an inline fuse holder and place the right fuse in it and join the wires together with connectors-- would think any spare parts place would have one

Thanks for your reply!
I thought of this as well, but I read in a Dodge service manual that they do not recommend in-line fuse holders for some reason. I think it's probably because the fuse does not make a solid soldered connection like a soldered strand of solid wire does.

Plus, I can't seem to find any information indicating what fuse rating I would need to use an in-line fuse holder.
I notice that the fusible link wire that I cut out of the line appears to be about 14 or 16 gauge wire. I imagine the amp rating on an in-line fuse would need to be pretty high in order to equal the burn thru equivilency of 14 or 16 gauge wire.

[jd585]

pardon, but that idea of fuse not making connection doesn't make sense since fuses are in the holder, get one of the type that has fuses like the car that plug in, start low and replace with spares until it doesn't go bad up to 30amps

what do you think

[harkauto]

Originally Posted by jd585

pardon, but that idea of fuse not making connection doesn't make sense since fuses are in the holder, get one of the type that has fuses like the car that plug in, start low and replace with spares until it doesn't go bad up to 30amps

what do you think

Thanks jd585. Like yourself I would think the same is true.

I just returned from the local library and read again in a Dodge service manual that in their earlier models they did have a fuse holder type of fuse system in place between the battery positive post and the alternator, but they kept having problems with the inconsistent voltage surges in this line which is caused by changing loads on the electrical system which kept blowing these in-line fuses.
The book went on to explained that this kind of fuse worked fine until additional load is placed on the electrical system by turning on the headlights and the heater fan on high for example, they found the fuse holder type of fuse could not hold up and was constantly blowing fuses. They then discovered that by installing a solder connected fusible link into the system the problem was solved.

[jd585]

perhaps the book was dated. most current cars and lorries uses inline fuses to 80amps.

i use an electronic service manual system i purchased through customer service at a place online, maybe you need one of these

[harkauto]

Originally Posted by jd585

perhaps the book was dated. most current cars and lorries uses inline fuses to 80amps.

i use an electronic service manual system i purchased through customer service at a place online, maybe you need one of these

I'm considering the in-line fuse holder method as suggested, but I'm wondering how I can determine what size fuse rating I need and then if it turns out that I need a 60 or 80 amp fuse....do they make fuse holders that large.

[jd585]

quick look in the data shows it was a dark green link, and checking at a spare parts place shows the alternator max output is either 80 or 120 amps.

rarely do alternators run at max power, so thinking 80 amps would be safe, i've seen inline fuse holders that can handle the 40 amp plugin fuses, so why not a series parallel circuit with 2 holders and 2 fuses. sounds like max power would be safely handled as well as normal usage

[harkauto]

Originally Posted by jd585

quick look in the data shows it was a dark green link, and checking at a spare parts place shows the alternator max output is either 80 or 120 amps.

rarely do alternators run at max power, so thinking 80 amps would be safe, i've seen inline fuse holders that can handle the 40 amp plugin fuses, so why not a series parallel circuit with 2 holders and 2 fuses. sounds like max power would be safely handled as well as normal usage

Thanks for the info.
Any idea what gauge of wire I would use with this set up?
If I recall.....the fusible link that I cut out of the line had a yellow stripe running the length of th black link. Does that yellow stripe indicate anything?

[jpb53]

Google is your friend.
http://minimopar.net/electrical-links.html

[harkauto]

Originally Posted by jpb53

Google is your friend.
http://minimopar.net/electrical-links.html

Hey Thanks jpb53! This has been a great help!
My probleme with using Google is in knowing what to type in for a search.

[dalet]

the fusible link is not copper stranded wire. it is braided wire but it is made of material that will melt when shorted to ground. there are different gauges of fuse link. you can the newer vehicles use different types of cartridge fuses. each different gauge of fuse link has a different amperage rating. if you can find out what amperage the circuit is you can install a cartridge type fuse. i believe the fusible link wire is still available.

[harkauto]

Originally Posted by dalet

the fusible link is not copper stranded wire. it is braided wire but it is made of material that will melt when shorted to ground. there are different gauges of fuse link. you can the newer vehicles use different types of cartridge fuses. each different gauge of fuse link has a different amperage rating. if you can find out what amperage the circuit is you can install a cartridge type fuse. i believe the fusible link wire is still available.

Thanks dalet!
Yes, you are right, the fusible link wire is still available but a bearcat to find. With research I found mine to be 12 gauge fusible link and found it at O'Riely's Auto Parts. None of their retail stores had any in stock but they did have it at their Distribution Center here in town. I had to buy a 20' roll of it and it cost me $12.00 and I used a total of about 8".
I simply cut out the old link.......cut back the insullator on the existing wire about 1".....bared 1" of the new link wire on each end, then wrapped each end of the new link around the ends of the existing, soldered the ends in place...... wrapped them good with electrical tape....and PRESTO!!!......BACK IN BUSINESS.

[rickk2586]

A mechanical fusible link is a device consisting of two strips of metal soldered together with a fusible alloy that is designed to melt at a specific temperature, thus allowing the two pieces to separate. Mechanical fusible links are utilized as the triggering device in fire sprinkler systems and mechanical automatic door release mechanisms that close fire doors in warehouses, etc. Some high-security safes also utilize fusible link-based relockers as a defense against torches and heat-producing tools. Mechanical fusible links come in a variety of designs and different temperature ratings.
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2013 MERCEDES BENZ SL-CLASS

[doujaco]

I have been searching for information on value's for fusible links and ran across this forum. I thought I'd throw in a couple of my thoughts or opinions.

First, I called my local NAPA store and they had about half a dozen ratings of fusible link wire in stock, but they said it isn't indexed in their parts guide. I would just need to know what size. Okay.. at least a source. (I haven't found anything yet to tell me the rating on the link.)

With a background in electronics repair, a couple of things in the forum worried me. First, someone suggested getting two 40 amp fuses and putting them in series to get an 80 amp circuit protection. Fuses have as close to zero ohms resistance as you'll probably find outside of a printed circuit. They are not equivalent to resistors or batteries in that you cannot add them, either in series or parallel to change the total value. They are a current sensitivity device. A certain amount of current generates a given amount of heat and literally burns the fuse open. A 40 amp fuse, (or 40 amp handling piece of wire) will go (hopefully) at 40 amps. So if you put two of those in series or in parallel one is going to go at 40 amps in the circuit.

There was also a discussion about using the gauge of wire to determine what size braided wire you might use to substitute for the fusible link. This is a false assumption. Density of the individual strands and material will both factor into the current capability of the wire. If you recall the banning of aluminum wiring in general home (in wall) wiring, it was because the aluminum heats up faster and therefore burst into flame faster than comparable copper wire.

Finally, there was a discussion about using a 60 or 80 amp fuse because that was the output rating on the alternator. Fuses are intended to protect wiring from melting down. You have to know what the rating is on the circuit you are seeking to protect, not the current creating ability of the voltage source. If you don't believe that, take an ammeter and connect it directly between the terminals on your battery and look at the instantaneous current available. You will not find fuses with this high of a rating in your vehicle.

I'm not meaning to rant. I only hope to save someone some potentially expensive, and potentially deadly mistakes. Back in the 70's when I was first studying electricity and electronics I made similar assumptions and "helped" a friend get her dead van home by bypassing the fusible link and shorting a connection in the voltage regulator. Voila... rig started and was charging... and on the way home the wiring harness in the engine compartment burst into flames...