[C38] Alternators

[les]

I think in general, boats draw more current for longer periods.  This
means greater heat sinking ability, so the design of the regulators
probably incorporates that, at least if I were designing an alternator
for a boat, I would work hard to ensure that the total heat could be
dealt with without issues.  That is the first part.  

The second part would be how to get that current to the "common" for the
boat.  ON a car, typical currents are <=35A.  So frame grounding is no
problem.  And most likely up to 50A could probably be handled this way.
but when the currents reach >100A, for sure the bolts and washers would
induce losses that would cause additional heating and other problems.
At that point a separate cable, running shortly and directly to the
common point (probably the engine block, and possibly to the exterior
water) would be required to minimize losses and help prevent migration
welding (where the current causes atoms of one side of a contact to
migrate to the other.)

A third point would be environmental.  The marine environment we all
know is corrosive to everything ( A sailor is someone who will take the
most expensive thing he owns and put it in the most corrosive
environment on earth), and that would affect alternators as well.  With
the modern lifetimes of cars, that is probably not as great an issue as
times past, but still, there is some argument that marine stable alloys
are better.  The question is which alternator manufacturer uses marine
stable alloys and how do you know?  I don't know, but Balmar seems to
have a pretty good following, and experience generally counts when it
comes to the overall quality of a product (although advertising and
dissing the competition don't hurt.  Look at the Corvette, the third
fastest super car in the world, and how it is perceived by the auto
magazines)

In general, I used automotive parts on some areas of JACE, not many, and
I had a rebuilt prestolite marine alternator for a while.  It worked
well and when I removed it it was still in good condition.  I am pretty
sure the prestolite folks use a single alloy in the housing for their
alternators, but I am not sure of the various other components, and
that's the rub.

I would guess that basically an alternator is an alternator.  The engine
compartment is not exposed to direct salt spray, so probably the car
alternator would be OK.  However, if you are doing long distance
cruising, the other aspects, higher current, longer run times etc. might
tip the scale in favor of a high quality Marine alternator.  As you
found out, we have come to rely on the convenience and capability of our
electrical systems.

Regards,
Les H
On Sun, 2011-11-06 at 06:20 -0800, Larry Malmberg wrote:
> Marine vs. Automotive; what says the list?  And, I have discovered that
> there is a difference between the two, well at least I have been told there
> is.  It has something to do with the grounding, apparently automotive
> alternators ground to their case and marine alternators ground someplace
> else.  Having experienced charging problems on the way back from HI this
> year I am now acutely aware of my dependency upon the electrical system of
> Hassle.
> 
> I had wanted to utilize the KISS principal but then, I think it got out of
> hand LOL, laptops, water makers, inverter, sat phones, radar, chart plotter,
> instruments,  well the list goes on.  What is, if there is one, the most
> effective charging and regulating system out there?  I need opinions based
> upon your usage.  FYI I have four AGL 110 amp house batteries and one small
> AGL start battery.  Currently using a Balmar regulator and a converted
> automotive 90amp alternator.
> 
> 
> 
> 
> 
> Best regards,
> 
> Larry Malmberg
> 
> 7231 Boulder Avenue Suite 507
> Highland, CA 92346 PI 15211
> Telephone  909-208-1847
> FAX           909-991-7568
> 
> E Mail  Larrypi at roadrunner.com
> 
> 
> 
>  
> Life is short, Break the rules, Forgive quickly, Kiss slowly, Love truly,
> Laugh uncontrollably, And never regret anything that made you smile..
>  
> "The American Indians found out what happens when  you don't control
> immigration"
> 
> 
> "Life is not a journey to the grave with the intention of arriving safely in
> a pretty and well preserved body, but rather to skid in broadside,
> thoroughly used up, totally worn out, and loudly proclaiming; WOW-- What a
> Ride!"
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