[Public-list] 78 Amp alternator/Atomic 4

[Meinhold, Michael J]

Thanks, you are right about the marine alternator - these guys do a lot of
marine engine work, and they know I need a marinized alternator (and are
charging me for it!)

I could really use the higher charging rate as we do very little motoring.

Mike

-----Original Message-----
From: public-list-bounces at alberg30.org
[mailto:public-list-bounces at alberg30.org]On Behalf Of Rick Leach
Sent: Thursday, September 02, 2004 3:39 PM
To: public-list at alberg30.org
Subject: [Public-list] 78 Amp alternator/Atomic 4


Mike,

Good question...I'm interested to hear what the consensus will be.  In the
meantime, here are some thoughts:

On a 12 volt system 35 amps is equal to .56 hp and 78 amps is equal to 1.25
hp, a difference of about .69 hp.  If you factor in a generous "fudge
factor" of, say, 25% loss due to inefficiencies in the mechanical-electrical
conversion the difference is closer to about .86 hp.  The impact of the
additional load will vary with your RPM's.  At lower speeds it will
represent a  greater percentage of the engine's output.  If you're properly
propped and spend most of the time running near the "sweet spot" in the
power curve I doubt that you'll notice it very much.  

There are some issues with a basic automotive alternator with regard to
operating it in a potentially flammable atmosphere.  I believe a proper
marine alternator is "ignition-protected" to minimize sparking that could
ruin your day, thus negating any savings.  

If you have enough load to justify it, I think a high-output alternator is a
good idea, but a proper marine alternator is essential with a gasoline
engine.

Rick Leach
S/V Sugar Magnolia, #121
Monterey, California


****************************************************

Date: Thu, 2 Sep 2004 11:51:26 -0400 
From: "Meinhold, Michael J" <MICHAEL.J.MEINHOLD at saic.com>

I need to replace or rebuild my alternator. Mamock Automotive is offering a
rebuilt Delco that will output 78 amps.
My old one was nominally 35 amps. My question is : should I expect my Atomic
4 to drive this alternator without slowing down much? Anyone have a similar
sized one on an A4?

Mike

Mike Meinhold
Rinn Duin #272
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