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

[Huw Powell]

> So - as far as I can tell - based on the what I have from the list so
> far:
> Fuel Pump = 10a (always on)
> CIS = 10a (always on)
> Ignition = 10a (always on)
> Rad Fan = 20a (always on - at least for now)
> Heater Fan = 15a (always on in the winter ;)
> Brake Lights = 5a (on a lot)
> Computer, gauges, etc = 5a (always on)
> Head lights low = 55w x 2 = 110 w = 10a
> 
> So given this set - looks like I need 85amps (in the winter). Do the
> numbers look right?

Yes, and no.  They all look like good "estimates" - but I suspect they 
are all overestimates.

The car in stock trim would be using 85 amps (when the rad fan is on) 
without turning on the defroster or radio?  I doubt that.

Access to a decent high-current ammeter would answer your questions in a 
  matter of minutes with "real" numbers.  Hmmm, wait, more than a couple 
of minutes, you'd have to disconnect the alt and run on only the battery 
to have good numbers.

Oh, here's one for you - replace your brake and parking lights with the 
LED versions. A bit pricey, but lower current.

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/