jeepnut24

Im slowly wiring up my 5.3L truck motor, but I have what is hopefully a simple question. The factory truck has the Battery wired up on the driverside front, but the battery in my swap is in the passenger side back. The Battery positive to starter is pretty straight forward to wire up, but what do I do about the alternator wire? I saw that its a fuseable link. The factory wire is several feet too short. What is the proper and best way to rewire that to extend it? Can I use a high amp fuse and a bigger gauge wire? What size fuse?

Pop N Wood

iTrader: (1)

Fusible links have a certain amp rating that depends on the wire gauge. It is a pretty simple thing to google and get the rating. Finding the gauge of the fuseable link can usually be figured out by a field manual.

I replaced all the fuseable links with fuses. Pretty easy to do and much easier to tell when something cooks.

If I were you I would just hook the alternator output to your starter lug or whatever terminal you have powering your fusebox. If you are racing and need and external kill switch then you may not be able to do it that way. not an issue if you aren't

jeepnut24

Thanks, Ill be using the factory Truck Fuse box. Im going to look it over, and possibly use one of the maxi fuses in the fusebox. Otherwise Ill just put a new Maxi Fuse inline with the battery or starter lug. Is it better to run it to the battery directly, or through the fusebox or starter lug?

Pop N Wood

iTrader: (1)

I have always read it is better to run it anywhere BUT the battery. Otherwise you run the risk of over charging the battery because it is at a higher voltage than the rest of the car.

Admittedly most guys run it straight to the battery, but IMO not the best place.

Save yourself some wire and run it to the fusebox.

Marky522

iTrader: (8)

Wiring it to the battery is fine, you wont overcharge it, the voltage should be the same across the entire system (within 1/2 a volt). Keeping the fuse as close to the alternator as possible is the only thing i would be worried about. You could easily splice a wire to the factory alternator lead to make it longer, just make sure however you connect it there is a good connection and it is weather tight to avoid corrosion.

Good luck,
Mark

jeepnut24

So keep the fuse as close to the alternator as possible?

Doug G

Why not run the alternator wire to a common lug/junction block for powering accessories(lights and such) and then run a wire from there to the battery for charging ?

scmb

ok so im trying to figure out the same thing. i have the 8.0 sq mm fusible link and at this site http://www.whiteproducts.com/fusible-faqs.shtml it says that the 8.0 wire is 10 ga and that typically the fusible link is 4 gauge sizes smaller. so im trying to extend my fusible link on my 5.3 silverado harness and id like to add say a foot or two. so im thinking the right way to go about it would be to use 1-2 feet of 6 ga wire and basically put it in between the 8.0 wire and the battery cable that it currently attaches to. solder it and clamp it. any better ideas? the other thing that is said is to use a maxi fuse but i dont know if the alt i have is oem or not and so i dont know the amp ratings of it. i think the oem alts came with like 130 amps. what would be best if i were to go with the maxi fuse? get a new alt that has the higher ratings like 200 and get what size maxi fuse? 250? ive never seen the maxi fuses going up that high in amperage. so do you use one of the mega fuses like you use for the underhood fuse block? like this one http://www.defender.com/product.jsp?...3927&id=178148
any help would be greatly appreciated. thanks

Jeff Smith

iTrader: (44)

yes i use flsible link clsely to alt...

Pop N Wood

iTrader: (1)

You can just add the wire down stream of the fusible link, crimp and solder like you said.

fuses come in all different sizes. Once you have the fuse holder you can mix and match fuses as needed. Typically the fuse is sized to the size of the wire, not alternator capacity. Hopefully the wire and alternator size match. In my case the wiring is much bigger than the alternator output, so I used an 85 amp fuse to match the alternator rating. Keep the fuse or fusible link as close to the alternator as possible.

scmb

so how do you figure out what size fuse to use? i have the 8.0 mm fuse link so do you use that to figure the fuse size? or? im at a loss as to how to figure out the fuse size. and would i just use the 6 ga wire instead? thanks

Pop N Wood

iTrader: (1)

If you go back to that white products page you linked and click on their specifications link, it pops up this table which says a 8.0 mm fusible link is meant to protect 8 gauge wire. I like that web site by the way, they have a pretty good catalog of parts.

This site shows a table saying to use a 160 amp fuse to protect that size of fusible link. I would be tempted to go with a 130 amp fuse to match your alternator capacity. The biggest maxi fuse I could find is only 100 amp. I went with an ANL fuse and weatherproof holder I got from this place

Honestly, all you really need to do is cut off the 8 gauge wire in your current harness and replace it with a longer one. The only real problem with fusible links is sometimes people forget they are there and when one blows they end up replacing everything before they figure out the real problem.

scmb

oh ya it does say to use 8 gauge.
thanks for the web link. that is exactly what ive been searching for... instructions that hold my hand through the process. great web page

andysfbird

There are two things you need to know before sizing the wire one is the load (alternator output) the other is the length of the conductor. The length is important because of the voltage drop in a particular conductor. The longer the run the bigger the wire.
This is because the voltage drops as the amps travel down the wire. When the voltage drops the amperage goes up (ohms law). If the wire is too small to carry the load it will over heat and possibly cause a fire, not good.

The over current protection device (OCPD) ie. fuse, circuit breaker or fusible link is there only to protect the wire not whats in the other end of it. The OCPD has less current capacity then the wire. When a short circuit occurs the OCPD will fail and its job is done.

You should use an OCPD for all power wires except:
IMPORTANT! Never use an OCPD on the wire from the battery to the starter it will always fail. The conductor can handle the inrush of the cranking amps but a OCPD will do its job.

Refer to the national electric code NFP 70.

Refer to this link for wire size:

http://www.alternatorparts.com/wire_size_chart.htm