[Public-list] 78 Amp alternator/Atomic 4

Meinhold, Michael J MICHAEL.J.MEINHOLD at saic.com
Tue Sep 7 05:25:02 PDT 2004


Thanks to all for advice on alternators. It's definitely a marinized
(spark-protected) alternator.
I like to run the blower most of the time the engine is running - keeps the
cabin a more pleasant place, and this sucks a few amps that reduced the
battery charging time. I believe it will pay to have the higher amperage
available to charge both batteries, run the blower and burn lights at the
same time.

I took the kids out twice this weekend. We motored to Broad Creek on
Saturday and swam. I am still power-limited (1500RPM and 4 knots) and I
believe it's dirty valves. I am pretty sure my thermostat is overcooling the
engine and causing this problem so I've got another engine task to tackle -
at least I can go sailing!

On Sunday it was just me and the kids again. We had 16-20 knots from the
North, with 3ft waves. I had bit of trouble getting in and out, but a
fantastic sail across the bay. I sailed on genoa alone after seeing it
reccomended here, and it was fine, and much easier to singlehand.

I had just about mastered backing her into the dock in a calm, but she
behaved completely differently with 15 knots across the dock. I gave up and
brought her in bow first, which was difficult enough. I hope the raft-up at
Still Pond was alright during the blow on Sunday!


Mike
Rinn Duin #272

-----Original Message-----
From: public-list-bounces at alberg30.org
[mailto:public-list-bounces at alberg30.org]On Behalf Of Amy & David
Swanson
Sent: Friday, September 03, 2004 5:26 PM
To: Alberg 30 Public List -- open to all
Subject: Re: [Public-list] 78 Amp alternator/Atomic 4


I have a "marinized" Delco alternator similar to the one you are talking
about.  There is apparently a standard modification kit to make these safe &
legal on inboard boat engines (not surprising give the bazillion power boats
with gas V8's i them).  Withing the restrictions of a simple automobile-type
regulator, they seem to work well & are cheaper than a rebuild on the
Motorola or other standard Atomic 4 alternators.  Be aware that many are
"rebuilt" units, and like all rebuilt alternators, quality varies widely.
If I were doing extensive cruising, I would want a real marine alternator
(Balmar or similar) with a smart regulator.  But for weekending, my $75
Delco is great.

David Swanson
Strayaway Child
Alberg 30 #229
----- Original Message ----- 
From: "dan walker" <dsailormon at yahoo.com>
To: "Alberg 30 Public List -- open to all" <public-list at alberg30.org>
Sent: Friday, September 03, 2004 10:49 AM
Subject: Re: [Public-list] 78 Amp alternator/Atomic 4


> rick is sooooo right about the marine ignition protected alternator and
fires
> dan
>
> Rick Leach <RLeach at mbayaq.org> wrote:
> 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"
>
> 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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