How much amperage can an alternator support? no really...

[cody at 5000tq.com]

Quoting Brett Dikeman <quattro at frank.mercea.net>:

> On Feb 5, 2008, at 7:25 PM, cody at 5000tq.com wrote:
>
>> Changing the
>> pulley ratio to spin the alternator slower will move it most efficient
>> RPM range up to more like where your engine is usually running at
>
> Every alternator output graph I've ever seen shows increasing current
> output as RPM increases, not the other way around.  The curve roughly
> looks logarithmic, but provided you don't overheat the alternator, you
> still get more juice as speed increases.
>
> Brett

But in design on a street car the output peaks arround maybe 3,000rpm  
engine speed, with plenty of juice availible at idle range. If you  
slow the alternator vs. the engine you move the peak up higher, and  
since it's a race car it will not be sitting at stop lights so it  
doesn't need to charge at any revs lower then saaay 2,500. Therefore  
you use a pulley ratio to apply a torque advantage, drawing less  
torque from the engine to apply the same ammount to the alternator and  
being a race car thats run between say 3,500rpm and 7,000 most of the  
time the alternator will produce plenty of current for the lights and  
fan that will only be needed when the engines being run hard and can  
be turned off when it's at idle in the pits.

I never said anything about output decreasing with RPM, I said it has  
a range where it's more efficient - same output, less heat.

-Cody