Finding new Fusible Link specs (1 Viewer)

[bloc]

My LS swap will include a 160A alternator, and being double the capacity of the stock one, It seems improving "FL MAIN" which is the primary charging FL is required.

How would one go about finding a new link to run in its place?

Per the EWD they seem to spec that one at "2.0" as opposed to the 0.3 and 1.25 of the others.

Any ideas?

Edit: or replace it with a megafuse?

 

[mct75]

If it were me, I would run a brand new fused connection all the way from the alternator to the battery post. Some 6-ish AWG wire and a (gasp) 160 A fuse is in order.

You can't just upgrade the FL as then the fusible part just moves to somewhere else in the wiring harness.

 

[bloc]

I did plan to upgrade the main charge wiring but for continuity with the other ones wanted to keep this as a fusible link as well..

That said, I think the existing wire is 6-AWG at least. Definitely larger than 10 or 8. My plan was to find some 2 or 1/0.. but having trouble sourcing GXL in that size. I'm looking up charts for what gauge is required at different temps and the recommendation is all over the place.. 2 or 1/0 is overkill which will avoid issues for sure.

With a 160A alternator should I build in some overhead on the fuse?

 

[mct75]

The debate around wire sizing is lively and there are no hard and fast rules. If you go by what varying codes call for, the positive wire going to the starter should be 4/0 at least, and yet Toyota decided to use something much smaller and it works great.

Do you anticipate pulling 160 amps from your alternator often? Of course it will only supply what the electrical system needs, often less than 50 amps. What is the actual, real world current output of it? If 160A is only at redline with a dead 12V battery then you'll likely never see that. Just stuff to consider.

A 200 amp circuit breaker is cheap and would perhaps save you from popping a fuse in the middle of a winch pull. Not sure if those are recommended or not.

Amazon.com: InstallGear 200 Amp Manual Reset Circuit Breaker: Car Electronics

 

[bloc]

I do have a winch that is has been shown to draw more current than most in (magazine) testing, though I very rarely use it. That is the main reason I'm running dual group 27 batteries. Otherwise my electrical demands are pretty mild. I am planning to use the GM Body Control Module which has a current sensor and controls the alternator with a PWM signal.. so I'm not sure how much this alternator will "act" like a traditional setup.

Still.. while I'm doing all of this wiring I want to get the alternator sorted and not have to worry about it ever again. Thanks for the circuit breaker idea. I'll do a bit more research into how underhood temps impact those things and probably mount one to the back of the battery box.

 

[lazy]

I didn't upgrade my alt, but I just ran 8 ga (8 sq mm) fusible link directly from the alternator to the battery post. I use wirebarn's wire calculator and the general rule of thumb to size the fusible link 4 sizes smaller (if it calcs out to be 4 ga, you run an 8 ga fusible link). In your case, a 12 ga wire is good for a 1ft run of 160 amps w/ 2% drop. Since an alternator technically isn't a load and the battery is current limited, there isn't really much a breaker does. Opposed the fusible link which protects the wires in the case of a short.

I personally would avoid a circuit breaker because of the voltage spikes you'll see. If you do, you should do like 50% of the CCA of the primary battery. I've got about 23 ft of 8 ga fusible link and will cut off and send to anyone needing it at cost. I can crimp on ring terminal(s) as well.