Can someone explain to me why the factories use such a small charge wire with a larger alternator? For instance, my Yukon has a 145a alternator, yet the charge wire appears to be a 12g (or smaller) fusible link. How does 145a flow through that w/o burning up. Another example is my 96 Mustang, which comes with a 130a alternator. It uses 2 fusible links, probably 14g or 12g also. There seems to be a reason for this.
But yet, when upgrading an alternator there is a lot of talk about up-sizing the charge wire to like 1/0 wiring to get the max benefit of the alt.
Do the hot rodders know something the factory doesn't???
The first question I have is on the Yukon with the 145A alternator is there just one fusible link on it's output post ?. If it is one, what size wire does this then connect to ?.
I'm unsure as to some characteristics of how a fusible link works but everything I've read has the fusible link being a certain size smaller than the wire it is connected to. What I have yet to find is for a particular size fusible link to be connected to a wire, how does the length of the fusible link affect things. I have to think a 4" long piece of let's say 12 gauge fusible link will melt apart at some amperage flow and over a particular time frame but how does this change, or does it, when the same 12 gauge fusible link is let's say 8" long. I have to think the 4" will perform differently than the 8" length.
Another thing you might be seeing is, you say it looks like a 12 gauge fusible link. I wonder is this just looking at the outside diameter of the link or what ?. Maybe this link has a thinner wrapping on it that in previous designs. I know in the car audio marketing you can have two wires having the same outside diameter dimensions but one could have a larger core wire in it with a thinner insulation around it.
As far as you hearing about upgrading the charge wire to a 1/0, it may or may not do anything. It's all how things are now or if things get changed, would this upgrade even be required. GM designed what you have to work (or you hope they did) and if you were to later add some more electronics into the vehicle, this alternator wire upgrade may be needed. At that point you might also have to upgrade the ground connection like what people in the car audio business call the "Big Three".
Some of the newer GM vehicles have computer controlled alternators and maybe the GM design you are seeing on your Yukon allows for the wiring they have attached to the alternator to work. The computer may allow the alternator to put out let's say 145A for a particular amount of time but then the computer backs it's output down so the fusible link does not melt apart.