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

Vittorio Bares Vittorio.Bares at nuance.com
Wed Feb 6 18:38:19 PST 2008


Yer probably right - they are overestimates - I'll need to find someone
with an ammeter...We'll see what the 'real' numbers are... 

-----Original Message-----
From: Huw Powell [mailto:audi at humanspeakers.com] 
Sent: Wednesday, February 06, 2008 7:52 PM
To: Vittorio Bares
Cc: cody at 5000tq.com; quattro at audifans.com
Subject: Re: How much amperage can an alternator support? no really...


> 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/


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