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

[Huw Powell]

> I've got 580 watts of lights on the rally car, this will require 48amps
> to run. Typically the 4000 has a 90amp alternator, I know I could go
> with the heftier 110amp alt from a 200 or what not. 
>  
> But my question really is, how much amperage does the car need to run?
> The only other acc I have is the heater fan, radiator fan, a few gauges
> and lighting for those, brake lights, fuel pump, intercom system -
> potentially the wipers. How much amperage does an alternator (typically
> 20 years old) really produce?
>  
> My assumption is that the big current draw is going to come from the
> radiator fan, fuel pump and possibly the heater blower fan - but also
> the ignition (spark, etc)...

My coupe has an essentially stock alternator, and on high beams I'm 
running 400w of lights.  Car still runs and charges the battery fine 
even if I turn up the 480w of stereo up real loud.

I think the FP runs about 10 A, the CIS another 10 or so, and the coil a 
few.  The radiator fan might not come on much as long as you are in motion.

I would make sure to do a few things - install a good, accurate 
voltmeter (like the coupe/90Q ones), make sure your alternator/voltage 
regulator is in good shape, use a good battery, and make sure all your 
primary wiring and connections are in good shape.

The car will work down to about 9.5 volts or so, so if you are 
overloading the alt you'll have plenty of time to do something about it 
if you see the voltage running below 12.6.

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/