You need to learn more about the requirements of a marine
charging system. Alternator requirements have only little to do with
loads directly supported by the alternator. High charge rates are used to
recharge a large battery bank in a short period of time.

Doug
s/v Callista

"Tim" wrote in message
ups.com...
I've been following this thread a bit.

Good Lord!

What all are you pulling that would make the alt. run wide open? the
Alternator shouldn't be forced to pull any harder than ia max. of 75%
of it's capacity.

and by hooking a blower up to run cooler air to the alt. will only make
the alt. pull that much harder .

And what tickles me is that some of these companies will take an alt.
that was designed for say, 60 amps, then they will hot-rod it up to
about 175 or 220. by stuffing it full of wires and saying "this is
what you need" (gulp!) and charging you extra big bucks for something
that would requier special servicing.

I would advise checking and seeing how much your actual amperage pull
is (if you have a 100 amp draw, you need at least a135 a.rated "stock"
unit) , THEN go get a stock OEM unit (prestolite/leece-neville, large
frame Delco, Bosch etc.) and work with that. i think you'll get more
satisfactory results, and less cost involved as well.

Tim

Doug Dotson wrote:
You need to learn more about the requirements of a marine
charging system. Alternator requirements have only little to do with
loads directly supported by the alternator. High charge rates are
used to
recharge a large battery bank in a short period of time.



Doug, I'm glad you reminded me of that. I've run a starter/alternator
shop for the last 23 yrs. and maybe I missed something along the way.

Whether on a "marine" application, a 73 toyota corona, or a greyhound
bus, you have batteries, an alt/gen, a regulation system, and a
......load.

inverters, split voltages, hi/lo amp settings, DUVAC, etc, are all in
between.

The products you utilize in this situation is the key...

I suppose what I'm saying is, that you can buid a 350 chevrolet engine
and say "This things got 450 horsepower, You don't need that Cummins to
pull that 52 foot van trailer"! .. and in theory, that's true. But in
practicality..its waning badly.

Tim wrote:

Doug Dotson wrote:


You need to learn more about the requirements of a marine
charging system. Alternator requirements have only little to do with
loads directly supported by the alternator. High charge rates are


used to


recharge a large battery bank in a short period of time.





Doug, I'm glad you reminded me of that. I've run a starter/alternator
shop for the last 23 yrs. and maybe I missed something along the way.

Whether on a "marine" application, a 73 toyota corona, or a greyhound
bus, you have batteries, an alt/gen, a regulation system, and a
.....load.

inverters, split voltages, hi/lo amp settings, DUVAC, etc, are all in
between.

The products you utilize in this situation is the key...

I suppose what I'm saying is, that you can buid a 350 chevrolet engine
and say "This things got 450 horsepower, You don't need that Cummins to
pull that 52 foot van trailer"! .. and in theory, that's true. But in
practicality..its waning badly.



This might be where you are BOTH right...
It has been a while since I looked, my memory is that the ratings on
alternators is not standard.
It seems there are derating curves by manufacturer/model - 100 amp
rating is seldom (never?) continuous 100a.
Ya gotta read the fine print - sometimes not even on the box with the
alternator inside.

My bet is that the alternator will work for a long time ONLY when ALL
the conditions are met.
That includes what you all have been talking about, plus more obscure
factors like ambient temp.

That's 2 cents.
Skip

That's correct. My 160 amp alternator is cold rated at 160. At operating
temperature (too hot to touch) it only puts out around 135 or so. The
160 figure is really a marketing figure.

Doug
s/v Callista

"Skip" wrote in message
om...
Tim wrote:

Doug Dotson wrote:

You need to learn more about the requirements of a marine
charging system. Alternator requirements have only little to do with
loads directly supported by the alternator. High charge rates are

used to

recharge a large battery bank in a short period of time.




Doug, I'm glad you reminded me of that. I've run a starter/alternator
shop for the last 23 yrs. and maybe I missed something along the way.

Whether on a "marine" application, a 73 toyota corona, or a greyhound
bus, you have batteries, an alt/gen, a regulation system, and a
.....load.

inverters, split voltages, hi/lo amp settings, DUVAC, etc, are all in
between.

The products you utilize in this situation is the key...

I suppose what I'm saying is, that you can buid a 350 chevrolet engine
and say "This things got 450 horsepower, You don't need that Cummins to
pull that 52 foot van trailer"! .. and in theory, that's true. But in
practicality..its waning badly.


This might be where you are BOTH right...
It has been a while since I looked, my memory is that the ratings on
alternators is not standard.
It seems there are derating curves by manufacturer/model - 100 amp rating
is seldom (never?) continuous 100a.
Ya gotta read the fine print - sometimes not even on the box with the
alternator inside.

My bet is that the alternator will work for a long time ONLY when ALL the
conditions are met.
That includes what you all have been talking about, plus more obscure
factors like ambient temp.

That's 2 cents.
Skip

Doug Dotson wrote:
That's correct. My 160 amp alternator is cold rated at 160. At operating
temperature (too hot to touch) it only puts out around 135 or so. The
160 figure is really a marketing figure.

Another fine example of a tinker toy alternator.

Most of the so called marine alternators are just that, tinker toy
alternators.

Most are cold rated, strictly a marketing gimmick.

A true heavy duty alternator is hot rated, not cold.

At least they were when I was involved in their design a long time ago.

If you want to see some real alternators, look at Leece-Neville.

A 200 amp alternator is truly a hot rated 200 amp alternator, not some
toy that has to be derated if you read the fine print.

Of course, it will cost more, there ain't no free lunch.

Lew

"Lew Hodgett" wrote in message
ink.net...
Doug Dotson wrote:
That's correct. My 160 amp alternator is cold rated at 160. At operating
temperature (too hot to touch) it only puts out around 135 or so. The
160 figure is really a marketing figure.

Another fine example of a tinker toy alternator.

Most of the so called marine alternators are just that, tinker toy
alternators.

Define a tinker toy alternator?

Most are cold rated, strictly a marketing gimmick.

Most are rated bath cold and hot.

A true heavy duty alternator is hot rated, not cold.

As are most marine alternators. Both figures are useful.

At least they were when I was involved in their design a long time ago.

Welcome to the 21st century.

If you want to see some real alternators, look at Leece-Neville.

Do they make one suitable for marine applications? If so, then I will
take a look at them.

A 200 amp alternator is truly a hot rated 200 amp alternator, not some toy
that has to be derated if you read the fine print.

Doesn;t matter as long as on understands what is going on.

Of course, it will cost more, there ain't no free lunch.

Cost doesn;t amtter when it is a boat.

Lew

Difference is starter battery vs house battery. A starter battery
is generally discharged a small amount and then recharged quickly.
The alternator is then expected to power everything as long as the
engine is running. A cruising boat is a different animal. All the
boat systems run off the batteries for the most part. The engine
is run once or twice a day to recharge the batteries (not to
power the boat). Since a marine engine running without propelling
the boat has alot of excess horses, a large alternator is used to
charge the batteries as quickly as possible. Quite a different scenario
than a Toyota or a Greyhound.

Doug
s/v CAllista

"Tim" wrote in message
ups.com...

Doug Dotson wrote:
You need to learn more about the requirements of a marine
charging system. Alternator requirements have only little to do with
loads directly supported by the alternator. High charge rates are
used to
recharge a large battery bank in a short period of time.



Doug, I'm glad you reminded me of that. I've run a starter/alternator
shop for the last 23 yrs. and maybe I missed something along the way.

Whether on a "marine" application, a 73 toyota corona, or a greyhound
bus, you have batteries, an alt/gen, a regulation system, and a
.....load.

inverters, split voltages, hi/lo amp settings, DUVAC, etc, are all in
between.

The products you utilize in this situation is the key...

I suppose what I'm saying is, that you can buid a 350 chevrolet engine
and say "This things got 450 horsepower, You don't need that Cummins to
pull that 52 foot van trailer"! .. and in theory, that's true. But in
practicality..its waning badly.

large alternator is used to
charge the batteries as quickly as possible. Quite a different scenario
than a Toyota or a Greyhound.

Maybe differrent than a toyota, but not a greyhound, or fire and emergency
equipent.

Battery isolaters and a/or a DUVAC system work very nicely.

The isolator will seperate the cabin battery[s] from the engine battery[s] and
you can use the same charging system for both and have them seperated at the
same time.

Since a marine engine running without propelling
the boat has alot of excess horses, a large alternator is used to
charge the batteries as quickly as possible

Sorry, i didn't meant o leave that out of my last post.

you had a key thought. a LARGE alternator. And that is what I was meaning.
something likewhat you find on an ambulance....something that is stock OEM.
Not a small unit that is stuffed with wires.

High performance and heavy duty can be the same thing, But I haven't really
seen this in Balmar, Pentex, Alcon, Lestek, Powerline, and a some other
companies that specialize in "hot-rodding" small units to make them a
powerhouse dynamo.


Tim

"BSCHNAUTZ" wrote in message
...
Since a marine engine running without propelling
the boat has alot of excess horses, a large alternator is used to
charge the batteries as quickly as possible

Sorry, i didn't meant o leave that out of my last post.

you had a key thought. a LARGE alternator. And that is what I was meaning.
something likewhat you find on an ambulance....something that is stock
OEM.
Not a small unit that is stuffed with wires.

Small units stuffed with wires have served me well for years.

High performance and heavy duty can be the same thing, But I haven't
really
seen this in Balmar, Pentex, Alcon, Lestek, Powerline, and a some other
companies that specialize in "hot-rodding" small units to make them a
powerhouse dynamo.


Tim