Fusible Link

Truckin2003 · November 1, 2008

Ok so the wire from the positive post on the battery to the alternator corroded away. well it happened at the fusible link.

i replaced the whole wire with a new 6ga. wire from the battery to the alternator. There is now no fuse there. is this a problem?

thanks

97SierraGMC · November 2, 2008

i re-did the wiring in my truck...

0/1 Gauge Battery - to Cab

0/1 Gauge Battery - To Frame

0/1 Gauge Battery + to Fuse Holder Then 4 Gauge from fuse holder into Alt

8 Gauge From Frame to body in a couple places...

i put it on top of all the factory stuff though..

redvett · November 4, 2008

You have to have fuses in you home so it wont burn down so why not on your truck. Yes you do need the fuse link.

Truckin2003 · November 3, 2008

Question:

So could i install a inline fuse in the 6ga. wire i put in. like maybe one of those fuses that are used in power cables on aftermarket stereo systems???

If this is possible, what do i need? whats size fuse?

thanks

Alljackedup408 · November 19, 2008

yeah man.. dont mess around with wiring with out a fuse... my buddy did train horns on his truck... didnt fuse it.. and it caught fire by the battery.. burned a hole throught his inner fender cover (plastic) and just damn near burned it down.. luckily caught it when it started. I ALWAYS FUSE accessories.. no matter what it is....

Truckin2003 · November 3, 2008

BUMP for my new question above. please help i dont want my truck to catch fire and burn my garage down

thanks

minibike132 · November 1, 2008

Ok so the wire from the positive post on the battery to the alternator corroded away. well it happened at the fusible link.

i replaced the whole wire with a new 6ga. wire from the battery to the alternator. There is now no fuse there. is this a problem?

thanks

Only if you don't like fire.

5Alive · November 18, 2008

Question:

So could i install a inline fuse in the 6ga. wire i put in. like maybe one of those fuses that are used in power cables on aftermarket stereo systems???

If this is possible, what do i need? whats size fuse?

thanks

What you need is a fusible link that is 5.0 square mm in cross section, rated for 50 amps, about 6 inches long, unwrapped in free air, not enclosed within a harness or convoluted tubing, and incorporated into your 6 guage charging wire as near to the battery as feasible.

In general, fusible links are sized 2 guage sizes less than the parent wire they protect... so two wire guage sizes smaller than 6 guage would be 10 guage. And 10 guage is equivalent to 5.0 mm sq.

For what it's worth, GM uses 5.0 mm sq. fusible links on their factory auxiliary battery option for the charging wire. Two, actually. One between the battery and the relay, and the other between the relay and the starter. In additon, GM has a 40 amp Mega fuse protecting the loads from the Auxiliary battery.

Fusible links function differently than many fuses. It should be of interest to you why the factory choses fusible links for the main high current starting and charging circuits, versus fuses and circuit breakers elsewhere. Fuses of all types... Mini, Maxi, Mega, fusible links, and circuit breakers offer the same function, protecting against damage from electrical overcurrents, shorts, etc... but even though they do the same thing, they are obviously not all the same. Therefore, the logic that an inline fuse would be just as good is somewhat circumspect.

I would use a fusible link, since that is what every car I've ever owned and worked on has used from the factory for the circuit you are trying to protect. I don't know why the OEMs use fusible links, and since I'm not an electrical engineer, I'm not going to assume that an inline fuse would be just as good, because every production and professional (such as emergency vehicles) installation I've seen uses fusible links.

When searching online, I found that fusible links are used in battery charging and starting circuits due to their temporary high currant handling... they allow high amperage to flow for starting for example, where a fuse would blow within a certain number of milliseconds or seconds (depending on type of fuse sloblo etc), and a cirucit breaker would trip, cool, engage again, trip, and continue that cycle.

A fusible link on the other hand, works for protecting from catastrophic damage from a dead short that isn't consuming the current by turning a motor, but is instead just generating heat. Thus the link melts apart, end of current flow. That is why the fusible link needs to remain free in air, unwrapped and unbundled with any other harness. A sloblo fuse might still blo before your truck gets started, which would encouage the operator to use a higher value fuse... which then may not blow when required for protection.

It seems easiest and safest to replicate what the professional electrical engineers already worked out for the vehicle, rather than try to guess what will work. Capitalize on the engineering you already paid for with the price of the truck. Don't take my or anyone elses advise on the internet too seriously, without first looking at it through the prism of what was professionally designed not only for your vehicle... but is found in similar patterns thoughout most vehicles manufactured.

Oh, and on edit, I wouldn't regard "aftermarket stereo systems" products with much seriousness. Get hard parts from a real parts store. You can by 8 inch lengths of fusible link from Napa, CarQuest etc. It is packaged by Belden Wire & Cable, and other credible sources. A lot of car stereo stuff is marketing, glitz, and glam designed to appeal to the eye of a 14 - 24 year old. It looks big, phat, and fancy... but I have found much of that stuff to be cheap and cheesy, not long lived, and failing to consider basic material properties like galvanic corrosion between dissimilar metals, etc. The slick look and hype fetches the high price for little value.

5Alive · November 2, 2008

I personally know of three trucks with "custom" battery wiring... that burned.

One was totalled, completely. Took out his garage too.

Another, the guy's dad was smart enough to grab some bolt cutters, cut through the smoke filled garage (he almost needed the bolt cutters to cut through the smoke, it was so thick and what an awful smell electrical fires are), and cut the battery cable, which saved the truck and the garage, but not the big fancy thick aftermarket wiring he had installed (without a fusible link).

I forget the details of the third truck, I almost thought I exagerated to 3 for more of an impact, but I do remember the third truck was a Ford, and the other two were both GMC's, so I know there was a third truck among the folks I personally knew who had a fire due to unprotected battery wiring.

That's one reason I went with all factory wiring for my dual battery installation, but since then, I found out that NAPA and other quality auto parts stores sell fusible links, so you could just pick one up there and add it to the wire you've already bought.

One think I'd like to know is why OEM's use fusible links.... instead of Mega Fuses for battery to alternator and battery to starting or charging relay connections???