Ray,

You got a couple of good answers so far, but I can not resist muddying
the water just a little more. The rating published is often optomistic
as referenced to sailboat applications as they seldom run at rated speed
and are often charging at the top of the recharge curve so they won't be
near the published capability.

There is an available 90amp unit that is a bolt-in kit. It will just
take some looking as I do not have the part number available. I know of
two of these installations that were done by owners. A Yanmar dealer
probably would (expect to be quoted at least 250$us). Some sets I have
installed were a 500$ alternator and separate regulator package and the
owner has always been delighted.

Be aware that 90amp machine will eat near 2hp. That may be critical and
if you currently often run at full rack (wide open), you may wish to
include a field shut off to get those 2 horses back pulling. It will
also destroy drive belts that were less than terrific. Always have at
least one spare on hand.

I do several of these upgrades in a typical year. If you have any other
questions, I'm here a lot.

Fair Wind and Smooth Sea
Matt Colie

ray lunder wrote:
Ahoy, I could only find one technical reference for this which claims
it's a 30 amp alternator. Could this be correct? That's immeasurable,
that's minuscule- that's nothing. I measured about 13.2v output at
idle and I had to rev the engine to over half throttle to get 14.4v
out of it. (my batteries were topped up at the time if that makes a
difference).
It's on a 12hp Yanmar one cylinder diesel and I'd like to charge my
house batteries (220AH) and a 12v starting battery. If I'm beginning
to understand these things I'm to look for an alternator which will
produce 30% of my amp hour capacity. Since I'll probably charge the
two systems separately I guess that's around 70 - 80 amps. My crank
pulley is about 4" diameter, O.D. to O.D.. I need a 3" foot model to
fit my engine. Any similar experiences, recommendations, empowering
observations? Ok, the spell chek is complete, I had eleven errors.
Thanks again.

Ray,

I did not know that the kit was no longer available. You might try
contacting both Balmar http://www.balmar.net/ or Amptech (last phone I
have is 817-377-9966 - never found a web presents) and see if either
knows how to do this.

A field shut down switch is machine specific. It can be as easy as
shutting down the lead that goes from the engine instrument power
(ignition, but not on a diesel) or as hard as getting inside the machine
and adding the ability to disrupt the regulator circuit. Manual regular
regulation is not difficult, but on a variable speed driver it is a
receipe for disaster.

The most of the equation is simple 746watts=1hp E*I=W (Volts x Amps =
Watts) The only gray area is the machine's fan loads.

Yes, normal sailboat manuvering time is not enough to keep up the
battery of a cruising boat, but with a little attention and some fast
idle underway or on the hook, it can work.

Stay in touch.
Matt Colie


ray lunder wrote:
On Fri, 04 Aug 2006 10:33:37 -0400, Matt Colie
wrote:


Ray,

You got a couple of good answers so far, but I can not resist muddying
the water just a little more. The rating published is often optomistic
as referenced to sailboat applications as they seldom run at rated speed
and are often charging at the top of the recharge curve so they won't be
near the published capability.


Thanks, everyone. I visited the alternator guy today and got a few
options.
It seems the Yanmars are hard to upgrade because of the 3" bracket;
also, the internal parts are proprietary, no longer available to
distributors and therefore intentionally expensive.
If you go to a larger output you really need to go to a larger frame
as well or heat buildup and mechanical fatigue are issues. A larger
frame means potential mounting mismatches in my case.
100A = 3hp. I don't know where he got this figure but there's a
formula for converting amperage to hp, I'm sure.
He had one rebuilt Hitachi 55A model the next size up which is a
drop-in replacement for $300 and has the correct size pulley.
(LR155-31). I get to keep my old 35A as a backup. He didn't seem to
think this would be a big improvement in my case.
Or there's a new French Motorola 70A that needs a pulley modification
to make it 2:1 and is a size larger in frame and has an offset ear for
the adjustment arm so I'm not sure if it will fit or not. It has a
tach send too. It's $350 and I also keep my old unit. Both are
internally regulated. Once the batteries are charged it will just stop
putting out, right?
Having a one cylinder, low RPM engine also makes the charging curve
less efficient as Matt suggested so I don't know if just anchoring or
clearing port will be enough to keep things up. I have one 4.7A solar
panel but I can't see it being much use on a boat with a mast and
rigging and all. There's just no where on a small boat to fit it so
it's unobstructed. Thanks again and smooth sailing.

There is an available 90amp unit that is a bolt-in kit. It will just
take some looking as I do not have the part number available. I know of
two of these installations that were done by owners. A Yanmar dealer
probably would (expect to be quoted at least 250$us). Some sets I have
installed were a 500$ alternator and separate regulator package and the
owner has always been delighted.

Be aware that 90amp machine will eat near 2hp. That may be critical and
if you currently often run at full rack (wide open), you may wish to
include a field shut off to get those 2 horses back pulling. It will
also destroy drive belts that were less than terrific. Always have at
least one spare on hand.



Can you describe the field shut off? I read you can fit a high amp
rated potentiometer, like from a ham radio or tube gear and manually
control the output that way as long as your willing to monitor the
system. Can anyone describe this circuit?

I do several of these upgrades in a typical year. If you have any other
questions, I'm here a lot.

Fair Wind and Smooth Sea
Matt Colie

ray lunder wrote:

Ahoy, I could only find one technical reference for this which claims
it's a 30 amp alternator. Could this be correct? That's immeasurable,
that's minuscule- that's nothing. I measured about 13.2v output at
idle and I had to rev the engine to over half throttle to get 14.4v
out of it. (my batteries were topped up at the time if that makes a
difference).
It's on a 12hp Yanmar one cylinder diesel and I'd like to charge my
house batteries (220AH) and a 12v starting battery. If I'm beginning
to understand these things I'm to look for an alternator which will
produce 30% of my amp hour capacity. Since I'll probably charge the
two systems separately I guess that's around 70 - 80 amps. My crank
pulley is about 4" diameter, O.D. to O.D.. I need a 3" foot model to
fit my engine. Any similar experiences, recommendations, empowering
observations? Ok, the spell chek is complete, I had eleven errors.
Thanks again.

"ray lunder" wrote
He had one rebuilt Hitachi 55A model the next size up which is a
drop-in replacement for $300 and has the correct size pulley.
(LR155-31). I get to keep my old 35A as a backup. He didn't seem to
think this would be a big improvement in my case.

ray - This is exactly what we did on our Yanmar 2QM15 - We just use the
internal regulator, and as I mentioned before feed the alternator to the
house bank side of a Blues Seas ACR combiner. When the house batteries are
fully charged, the charge goes to the starting battery.

I was given the 55A alternator but was also sceptical that it would make
much difference. But, I am pleased with the results - I have not measured
the current, but the 200AH house batteries seem to reach full charge quite
quickly.

And, it's easy to swap back to the spare if you have a problem.

With a low horsepower engine, you have to compromise a bit - Maybe larger
solar panel would give you all you need?

GBM

1 horsepower [international] = 745.69987 watts (at 100% efficiency. ) (and
one watt is one volt-ampere of course) (For the arithmetically challenged
that's about 62 amps at 12 volts and 53 amps at 14 volts.)

Nigel Calder has written a couple of very good books on the care and feeding
of battery banks. There's a lot more to it than just an on/off switch in
the regulator. You can spend really big bucks for a good smart regulator.

The salesman probably got the 3 hp in the same place they got the 12 hp
output rating, but remember, if it were 100% efficient, it wouldn't get hot.

Roger

http://home.insightbb.com/~derbyrm

"ray lunder" wrote in message
...
On Fri, 04 Aug 2006 10:33:37 -0400, Matt Colie
wrote:

snip
100A = 3hp. I don't know where he got this figure but there's a
formula for converting amperage to hp, I'm sure.

Watts to HP....In 1492 Columbus divided the year in two and converted watts
to horsepower. 1492/2=746watts/hp
"Matt Colie" wrote in message
...
Ray,

You got a couple of good answers so far, but I can not resist muddying the
water just a little more. The rating published is often optomistic as
referenced to sailboat applications as they seldom run at rated speed and
are often charging at the top of the recharge curve so they won't be near
the published capability.

There is an available 90amp unit that is a bolt-in kit. It will just take
some looking as I do not have the part number available. I know of two of
these installations that were done by owners. A Yanmar dealer probably
would (expect to be quoted at least 250$us). Some sets I have installed
were a 500$ alternator and separate regulator package and the owner has
always been delighted.

Be aware that 90amp machine will eat near 2hp. That may be critical and
if you currently often run at full rack (wide open), you may wish to
include a field shut off to get those 2 horses back pulling. It will also
destroy drive belts that were less than terrific. Always have at least
one spare on hand.

I do several of these upgrades in a typical year. If you have any other
questions, I'm here a lot.

Fair Wind and Smooth Sea
Matt Colie

ray lunder wrote:
Ahoy, I could only find one technical reference for this which claims
it's a 30 amp alternator. Could this be correct? That's immeasurable,
that's minuscule- that's nothing. I measured about 13.2v output at
idle and I had to rev the engine to over half throttle to get 14.4v
out of it. (my batteries were topped up at the time if that makes a
difference).
It's on a 12hp Yanmar one cylinder diesel and I'd like to charge my
house batteries (220AH) and a 12v starting battery. If I'm beginning
to understand these things I'm to look for an alternator which will
produce 30% of my amp hour capacity. Since I'll probably charge the
two systems separately I guess that's around 70 - 80 amps. My crank
pulley is about 4" diameter, O.D. to O.D.. I need a 3" foot model to
fit my engine. Any similar experiences, recommendations, empowering
observations? Ok, the spell chek is complete, I had eleven errors.
Thanks again.

"Dave W" wrote in message
...
Watts to HP....In 1492 Columbus divided the year in two and converted
watts
to horsepower. 1492/2=746watts/hp

Several smart answers on conversion of units, but none on efficiency of
alternator and that is needed to determine actual HP needed to drive the
alternator.

The figure Balmar quote is 1HP per 25A output at 14V. Others quote even
higher loses.

For original poster, this link should provide much of what you need:

http://www.balmar.net/PDF/Alternator...or%20Guide.pdf

For a 3/8" belt drive, they don't recommend more than 75A. I would not
exceed this unless you want a lot of belt problems and the need for a
complex system to switch out alternator when you need engine power.
Personally, I would stay with the 55A unit.

GBM