At what rpm does an alternator generally make max current

Joined: 20 Apr 2007 Location: Lara, Victoria

and at idle how much current as a percentage of max current is being produced?

ie. max current at 2000rpm and 25% at idle

I've got a td42 patrol with stock alternator, but I think the figures will be about the same for most vehicles

Thanks
Rob

Joined: 18 Apr 2008 Location: rockhampton

Depends every alt has a different torque curve.

Posted: Thu May 01, 2008 12:03 pm

GQRob wrote:

and at idle how much current as a percentage of max current is being produced?

Have you heard about the Internet yet?

The internet, even Google is your friend!

I would be happy to get on the net and do some research for you?

Just send me a PM and I will do some searching for you!

Posted: Thu May 01, 2008 12:10 pm

True Story!

Because I was feeling guilty about being a smart=ass, I did a search myself and look at the time it took to find the answer and type this, using Google and the words - alternator output rmp, I found and read, then posted this -
http://www.rpc.com.au/products/batteries/car-deepcycle/carfaq5.htm

EDIT, I cant believe it was 7 minutes.

Joined: 20 Apr 2007 Location: Lara, Victoria

thanks for the reply's, I thought there might be a "nominal" figure or perhaps someone may have already tested a stock one. When I get a chance I will test mine and post some results.

Rob

Posted: Sat May 03, 2008 6:19 am

GQRob wrote:

I thought there might be a "nominal" figure or perhaps someone may have already tested a stock one.

Hey Rob, I'm guessing there is an "indusrty standard", for comparritive purposes.

Then there is the individual vehicle requirements, as you may be aware, like power taken away from the engine relative to the torque required to move the car, retain current speed and fuel consumption. The formulas for each vehicle would be varied and complicated.

As for someone testing one and giving you the results, it may not be perfect. How does one measure the result attained after recording the results?

Joined: 06 Mar 2006 Location: Melbourne-Australia

As each application is different there's no industry standard - manufacturers publish typical output curves of the alternator but this of course doesn't give the full story as pulley ratios are also required.

These ratios are governed by obvious things like engine RPM range and desired charging current at idle but also some less obvious ones like alternator noise.

Also the curves are NOT linear.

Posted: Sat May 03, 2008 7:52 pm

So, how long is a piece of string?

Joined: 06 Mar 2006 Location: Melbourne-Australia

Is it metric or imperial string....... Smile

Posted: Sun May 04, 2008 12:04 pm

LH or RH twist?

Joined: 11 Jan 2004 Location: Adelaide

v6hilux wrote:

So, how long is a piece of string?

chimpboy wrote:

This long: |<------------------------------------------------------------->|

(not to scale)

Posted: Sun May 04, 2008 7:29 pm

-Scott- wrote:

chimpboy wrote:

This long: |<------------------------------------------------------------->|

(not to scale)

I know the arrow head tips are supposed to be touching the lines, so that is not the correct length!