Thread: Main fusible link - what's the amperage rating?

What is a B13's main fusible link amperage rating? 70 amps? 80 amps? 100 amps?

can't find this information anywhere. I'm assuming it's closest to 80 amps.

It probably is, but then again, people install B15 and other alternators that are rated for 100 amps or so with no trouble, so...

That helps actually, thanks.

If anyone does know for sure, drop a comment

Yes, but the maximum current capacity of an alternator is no indication on how much the car is drawing. Your car can only draw as much current as there are loads to put on the alternator.

In other words, if the car has a maximum load of 900w @ 12v, it'll draw 75a, regardless of the size of the alternator, as long as the rated alternator max current capacity isn't less than the car can draw.

Ohms law ftw - Ohm's Law Calculator

C

Oh right, physics.

You would think that people don't just toss uprated alternators in their systems for nothing though, right?

The main reason you would upgrade to a higher amperage alternator would be because you've added more load than the stock one can satisfy. Examples would be high wattage driving lights, or a few large audio amplifiers.

It's not much different than fuel injectors. Would you put 550 injectors on a stock DE? The stock 259cc injectors can deliver more than enough fuel to support the horsepower, so you'll only be using a small fraction of the 550 injectors capacity. A home electric service panel is another example. You COULD install a 200amp service to in a one room bungalow, but if all it has is a light bulb, and few appliances, you've wasted your money.

C

Why are you hunting for this info? Maybe we can help in other ways.

That's my point though. Stock alts are delivering 77 amps at 5k + rpm (IF you're needing that much load). If someone is popping in an alt that can deliver 20+ more amps at the same RPM, surely they have a higher wattage load they need to deliver to, no?

And if that's the case, then it would mean that the main fusible link is probably rated higher than 80 amps, or otherwise they would be popping it when delivering that extra wattage. That would rule out two of the possible ratings that I have in mind.

This is why I need to know for sure though, can only get so far with guesstimating.

Ben, I'm wiring up my rally car and following the stock diagrams, I need some sort of protection on the power feed from the alternator. Ideally it would be a fusible link, or maybe a circuit breaker. The problem is I need to know the amperage rating of the stock fusible link or circuit breaker. The factory one I have is frayed and somewhat corroded, and replacements seem hard to come by. If I could find a universal type similarly rated fusible link or circuit breaker then I would consider it an reliability/serviceability upgrade over stock.