Hello All
I have read many glowing reports on the Powertwist belts..
I was wondering if any of you trawler drivers have
ever used these belts on your boats as a permenant
replacement for the common v-belt ? I would think
they would be great in a marine environment...
Mike Danforth
52' Defever L.R.C.
Ft Pierce Fl

Mike wrote:
<I would think they would be great in a marine environment...>

They sound great but a quick look at the specs show an absolute max temp of
100 C and if operated over 70 C "consult factory" is the note. This would
let them out on any of my belt applications as 70 C is a pretty low limit.
YMMV

We are looking for some really good belts that can deliver the 8-10 HP for
our yet to be bought 200-250 amp continious 24 volt alternator output. Flat,
cog, V or ???  Any suggestions?

Dave
Swan Song
Roughwater 58
Tortola, BVI......tho not much longer ;-)

Steve Dashew says:

"One last thought if you're thinking about big alternators. The high
horsepower requirements put big strains on the drive belts, alternator
brackets, and pulley tensioning devices. Add in the power pulses which are
inherent in all diesel engines, and it takes muscular engineering for all of
this gear to stand up over time. If you are using V-belts, be sure that belt
wrap, pulley diameter, and belt specifications are up to the task. And be
certain that the alignment of the pulleys is spot on. Any dusting of the
belts is an indication of alignment problems. Belts which slip create huge
quantities of additional heat. With these John Deere diesels we're using
"poly-V" belts or ribbed belts as they are sometimes called. This is the new
thing in drive belts - more reliable and better at power transmission with
less belt tension. It took us some time during sea trials to get the drive
belt scenario just right, but we've got 800 plus hours on them now without
any signs of major wear."

See: < http://www.setsail.com/dashew/ac_systems.html > I have trouble seeing
your needing that much continuous amperage.

Ron Rogers

----- Original Message -----
From: "Dave Cooper" captdave@surfbvi.com
|
| We are looking for some really good belts that can deliver the 8-10 HP for
| our yet to be bought 200-250 amp continious 24 volt alternator output.
Flat,
| cog, V or ???  Any suggestions?

Ron wrote:
<See: < http://www.setsail.com/dashew/ac_systems.html > I have trouble
seeing your needing that much continuous amperage.>

G'day Ron, unfortunately in the tropics the combination of the wind, waves
and 85 to 95 degree temperatures require the boat to be reasonably shut up
underway.

So we require two AC units to be running along with the usual other loads of
boat operation. We could run the genset for this but why run two engines,
main and genset when one can do the job? We have two 4000 watt Trace
inverters to run all our loads.

With 800 AH of 24 volt AGM batteries to be charged and the draw of the AC
units the amperage is in fact up at the 200-250 continuous level aka the
4-5KW's.

I am quite familiar with Steve and Linda's solutions to the issues they see.
I have had many conversations with the Electrodyne folks in Maine. Their 300
amp 24 volt units are priced in the $2500 ea bracket and are most likely
well worth it. However, needing a spare in case of failure puts the price up
a bit. This unit needs about 13-15 hp to drive. Too much for reliable long
term V belts operation I think! A hard drive via a shaft won't work as the
crankshaft speed is too low (15-1600 rpm). So this unit would make a
marginal system, IMO. Plus the diode box requires more space and mounting
issues

Looking at splitting the load between two smaller 150 amp alternators, one
on the crank and one on the camshaft drive gives a bit of redundancy. Unit
like the Zena 200 amp unit might be a better solution at $6-700 each plus a
spare. Going this route one would need the lighter load of ~10 hp to drive
them. Doable with matched 1/2" conventional belts but perhaps better with
cog or a flat "v" belt. Using serpentine belts doesn't seem feasible as
mounting a tensioner on the old 6-71 would be difficult.

Using this split load method would also allow a spare unit to be carried to
keep the system operation with one failure and at 50% with two failures.
Better odds at a lessor price I think. Comments?

Any other suggestions or experience with 2-3KW 24 volt alternators that I
might not be aware of would be appreciated. So far the ZENA folks seem to be
a leading candidate. 3 year warranty and reputed quick turn around on any
repairs requiring return.

BTW someone was asking about alternator brackets last week...can't find the
email but Zena seems to have a selection.

Cheers

Dave
Swan Song
Roughwater 58
Tortola, BVI

Billie, of Billie's Battery Shack fame in Marathon also made the observation
that painting or powder coating reduces heat transfer and exacerbates
overheating of alternators.

                                      Regards....

Phil Rosch
Old Harbor Consulting
M/V "Curmudgeon" MT44 TC
Currently lying Bond Creek, NC

-----Original Message-----
From: Scott H.E. Welch

I used two PowerTap/Ample Power 150 Amp 24 volt alternators on Island
Eagle, both mounted to a new custom alternator bracket and both driven
from the auxiliary drive on my GM 6-110. This runs at 2X crank speed,
which is good as I cruise at 1350 RPM. I machined up a custom 4-belt
drive pulley that gives me a 2:3 drive, for a final alternator speed of
4050 RPM at cruise (and more to the point 2100 RPM at idle.

REPLY
Scott, out of curiosity, why did you pick a ratio that did not produce
the peak RPM for the alternator armature at max useable engine RPM?

Scot wrote:
One last note, with such large alternators you need to worry about side
loading on the drive shaft. I solved this by driving both alternators
off a single pulley but with the belts running about 180 degrees from
each other.

REPLY
Excellent design. I wonder why more engine/boat builders don't provide
such a detail?

Scot wrote:
A few other things I will share:

1. When I was looking at alternators I had the chance to visit Ample
   Power and chat with the owner, David Smead. This guy is a serious
   12-volt geek (and coming from me that is a real compliment). Among other
   things, I asked him why his alternators were bare aluminum instead of
   fancy powdercoating like Balmar, and his immediate answer was that
   powdercoating will reduce thermal transfer efficiency by a few percent
   and make the alternator run slightly hotter. So he'd rather a bit less
   pretty for a bit more performance. I like that!

REPLY
Correct facts but incorrect conclusion. As David Smead says its only a
few % points.
The casing is not the major heat dissipator. The heat sinks of the diode
matrix is the single largest heat dissipator and the fins on that heat
sink is the method of getting rid of this heat. Air flow is the medium
of heat exchange, so internal air flow is far more important in terms of
cooling than surface coating and or color is.
Powder coating is not cheap. It can screw up close tolerance machining
like the bearing seats, so there is a cost benefit to not powder
coating.

The stator also becomes a source of heat that requires dissipation from
the stator windings, but again the case coating is not a factor. Air
flow is.

A more significant modification to the case is providing more holes in
the case to allow greater air flow through the insides of the
alternator. That makes a huge difference in cooling. A second major
design feature is how the fan blades are designed and where located.
Prestolite make a small frame alternator which has a fan mounted at the
back of the shaft right next to the diode heat sink and a second fan
mounted in the usual place next to the drive pulley.

The primary justification for painting or coating the alternator frame
is to prevent oxidation of the aluminum surface. Aluminum oxide is an
abrasive. When engine vibration shakes the alternator case, some of this
fine abrasive can shake loose and fall into he stator windings where it
gradually abrades it way through the magnet wire insulation.
Eventually this causes inter-winding shorts that will impair the
performance of the alternator.
Not to knock Ample power specifically, but if given a choice of a coated
alternator shell or an uncoated shell, I would choose to have it coated.
Color is not important.
I would also choose an alternator with vacuum impregnated coils over one
which does not have the windings encapsulated in epoxy.

Something else which is rarely mentioned about alternator design is the
shaft diameter and the style of bearings used to support the shaft front
and rear.
It has absolutely no effect on amp output but is quite relevant to
overall equipment longevity. But I guess no one cares about that.

Scott wrote:
3) The house alternator runs HOT! It's pumping out 150 Amps and let me
tell you you don't hold your hand on there for long. I will be fitting
both alternators with thermostats and alarms. I also fused the outputs.

REPLY
The single biggest improvement you can do to any alternator regardless
of brand, design and loading is to improve the cooling air flow through
the insides of that alternator.
More cooler is better. And as Scott has done, having a way to monitor
and alarm any heat build-up in the alternator is a major design
improvement.

Cheers

Arild

All this discussion of high powered alternators got me thinking about
battery charging.

While it is true that a totally depleted battery can handle a lot of
charge current during the initial stages of bulk charging, it is equally
true that the final stages of absorption must be done gently and over a
long period of time if you expect the maximum life span from these
batteries.

The reality is that a deeply discharged battery plate has been depleted
deep into the plate thickness, not just the surface layer. Consequently
it will require an equally long charge period to fully penetrate the
plate interior with a charging current and reverse the lead sulfate that
has formed. Converting this lead sulfate back into sponge lead and
sulphuric acid requires time.

In live-aboard situations there is always some connected load even
during charging. This connected load varies from a single light to a
small fridge to the occasional surge when a pump starts or toilet
flushes.
When charging from a genset, it is recommended to curtail the charging
when you reach 75% - 80% of full. This is to avoid running your genset
light load and burning a lot of fuel for little return.

As long as you return to a dock and use shore power to completely finish
the recharge over a day or two, the battery will likely not suffer great
harm.
However, if you are in the habit of always anchoring out and always
charging from a motor driven alternator, the picture alters for the
worse. Chances are you never fully  saturate the battery plates with a
full charge.
Having a solar panel of several amps output is a good way to overcome
these charging shortfalls.
If your solar panels or wind charger can deliver 5 - 10 amps of charge
current on a steady basis then you may be able to drive the battery
plates right up to the full voltage of 14.5V needed even if some
connected loads are draining away from the charge.

This is an aspect of charging which received very little attention in
most applications.

Regards
Arild

-----Original Message-----
From: trawlerphil
Billie, of Billie's Battery Shack fame in Marathon also made the
observation that painting or powder coating reduces heat transfer and
exacerbates overheating of alternators.

                                      Regards....

Phil Rosch

REPLY
I would like to see some substantive data to support Billie's (of
Billie's Battery Shack) statement.
In an earlier post Scott Welch quotes David Smead of Ample Power as
saying:
"that powder coating will reduce thermal transfer efficiency by a few
percent and make the alternator run slightly hotter".
So just how much is this "few percent" and just how much is this
"slightly hotter?
Unless you are pushing the envelope right to the max; will this even be
a measurable difference five years down the road? Is it significant
enough to justify extra $$$$ in purchase price?

Back in 2001 one of the boating magazines published a documented
comparative test of Ample Power and the equivalent power output Balmar
alternator. (Sorry folks, I do not have a copy on hand)
As I recall, the data indicated that Ample Power unit ran slightly
cooler in the first hour, then gradually lost the advantage and after
five hours of continuous maximum rated output, the Balmar was actually
running slightly cooler. However; both units performed well, both units
continued delivering rated power output, and both units did not suffer
any apparent damage from the heat.

In other words, powder coating did not confer any definite advantage or
liability.
Other factors has to be considered in deciding if one or the other brand
is superior.

Among them might be the following.
Price and availability from a local supplier
Tech support in configuring the complex regulator associated with each
model alternator.
Mounting and pulley configurations to suit YOUR particular installation
Ready availability of spares such as bearings, brushes and diode matrix
blocks.
Your local dealer after sale support.

AS a for instance, one local Ample Power dealer claims he has absolutely
no problem driving the 150 Amp alternator with a single belt. Oh yeah??
Bet he doesn't have to cover the cost of re-placing your water pump
bearing a few months down the road. He never says for how long that belt
will last. He never mentions if this single belt is a special belt only
available through him.

Likewise, I know another local alternator supplier who can provide me
with a Prestolite or Leese-Neville alternator that looks and performs
identically to a Balmar branded alternator at half the price I pay for
Balmar. However they do not sell any regulators whatsoever.
The reason is actually quite understandable. They grew tired of DIY
fumble fingered boat owners getting all confused with the intricacies of
installation and expecting the alternator shop to provide free tech
service and trouble shooting skills for something they are not
responsible for.
Can't say I blame them.

The reality is, only a few manufacturers make the castings, stator
cores, and armatures etc. used in 90% of all alternators. Specialty
branded alternators are assembled and created by using these same basic
parts but modified as to quality of magnet wire, bearing selection and
even shaft diameters. The method of assembly, ease of replacing wear
parts like brushes and bearings is a significant cost over the service
life. Something as subtle as whether a sleeve or needle bearings is used
in the tail piece may influence service life. Air flow and heat
dissipation of the diode matrix block is far more critical than any
paint scheme. How well is the air flow designed in that particular case?
Is the mounting foot arrangement sufficient to prevent vibration? If
not, be prepared for frequent and annoying breakdowns.

How easy is it to add or replace the external regulator? Some
Leece-Neville models allows you to  do it without dismounting the
alternator. Other models requires a hydraulic press to open the case.
An excellent suggestion is that of remote mounting the diode block for
better cooling. How easy is that to do on the model you are
contemplating installing?

Mention has been made of Electrodyne's brushless design. Good idea!
However, this is also available from other manufacturers without the
much higher cost associated with Electrodyne.

Something as stupidly simple as fan blade rotation may be significant.
Sometimes it is much easier to mount an extra alternator backwards
relative to the engine.
With a bi-directional fan, cooling air flow is not affected when you
reverse the rotation.
But on some models you cannot get bidirectional fans or an optional
counter rotating fan assembly.

How about an isolated frame. Some models do and some models do not have
this feature.
With the new digital diesels this is going to be a significant issue in
electrical system design.

So if you are going to compare apples with apples; get past the powder
coating!

Cheers

Arild

Arild wrote:
<How about an isolated frame. Some models do and some models do not have
this feature. With the new digital diesels this is going to be a significant
issue in electrical system design.
So if you are going to compare apples with apples; get past the powder
coating!>

So far I have had many private replies to the question I originally asked
but don't seem to be as close to having the information to make the best
decision as I'd hoped yet. But as you see when reading down the list the
Electrodyne unit is still looking good ;-)

1. 250 amp steady state 28 volt DC output is required.
2. One or two alternators can be used to provide this.
3. The max engine RPM and drive pulley is 7.5" so a 1:3 ration is about the
   best that can be expected.
4. The engine rpm is a nominal 1500 with a max of 1925 resulting in a
   nominal alternator RPM of 4500.
5. Space required is not a big issue
6. Reliability is a major factor which a two unit solution seems to make
   attractive.
7. Isolated ground is a must.
8. Must be externally regulated preferably without surgery to the alternator
9. A suitable vender that can/will supply the pulleys, brackets, and other
   support in addition that one might expect with a few BU purchase.
10. Case color doesn't matter ;-)

There are many vendors of 125A 28 volt alternators at first blush:
Electrodyne, Balmar, Prestolite, Leese-Neville, Powertap, PolarPower,
AuraGen, Zena, Amptech & Eco-tech. Then there are the oil and water cooled
units & the ones from Fisher-Panda. I've missed a couple that I can't seem
to recall at this moment. Don't forget the Chinese knock-offs also!!

The choices from the above vendors list seems to narrow down pretty quickly
due to two of the requirements. First, low alternator speed and second, the
isolated ground requirement.

We have left; Electrodyne, Balmar, Prestolite/L-N. Of these 3 I haven't been
able to find a vendor that can help much with the Prestolite/L-N units from
afar. So now down to two.....both pretty pricey options at $1800+ each!
However, the Electrodyne claims 15-20,000 hours of operation without any
service! This has to be worth some piece of mind and long term $ benefit. It
would tend to make us think of not carrying a spare especially with two
units already. We can't seem to get any numbers from Balmar on their unit in
this category.

Another reason that tends to favor the Electrodyne is that at the 125
continuous amps required the unit is loafing which should be good for long
term life. It is rated at 250 amps continuous at 2650 rotor RPM. They claim
a high  "mechanical to electrical" efficiency. I have one chart from them
that shows 7.5 HP required to drive it at 150 amps @28 volts level. This
would workout to around 4200 watts output for 5600 watts of engine power or
~75%. Does this imply that 1300 watts is going up as waste heat? That's
about ~4000 BTU per hour if so. Comment?

With such a low rotor RPM required for full output on the Electrodyne a 1:2
ration would seem to be a bit better. More belt wrap and lower rotational
loss from friction. This should help the overall efficiency especially as
we'd only be using 60% of it capacity at the driven rotor RPM.

Now on to regulators for this system. I think that's another thread though
it has been flogged somewhat recently.

BTW, does anyone have the status of PolarPower? AuraGen is apparently in
Chapter something trying to reorganize and PolarPower has gone silent! Both
of these companies have very interesting products that have been sold and
work well. They seem to have missed something in their marketing though as
they are both "better mousetraps", IMO

Comments?

Dave
Swan Song
Roughwater 58
Tortola, BVI

(SNIP) So if you are going to compare apples with apples; get past the
powder coating!

First, Bob McLeran said Bobby checked out a few months ago. The keys have
one less genuine conch.

I don't know whether power coating raises temperatures or not and only the
manufactures have deep enough pockets to do controlled testing, but it
passed my "sniff test".  Having said that almost all urban legends also pass
a "sniff test", so who knows?

What I do know is how these alternators operate on my boat.  The one driving
the 12 golf carts primarily runs at 181 degrees while working (most of the
time) and 154 degrees when it is reasonable caught up. I've replaced the 50
AMP rectifier with a 70 amp unit, and cooked the stator.  Full time cruising
in the tropics seems to require an annual "rebuild" for the port alternator
which I'm willing to live with given how hard it works. I carry a backup
alternator, same size and rating.

I run my belts fairly loose because it's cheaper to replace belts than water
pump bearings.

Works for me, YMMV...

                                      Regards....

Phil Rosch
Old Harbor Consulting
M/V "Curmudgeon" MT44 TC
Currently lying Bond Creek, NC

I run one hour in the morning and around an hour and 15 minutes in the
evening.  My Heart 2500 starts at 130 amps and I shut down the generator
when it reaches 70 amps. My guess is this is at the end of the bulk charge
phase.  It works for me and my Trojans, YMMV...

                                      Regards....

Phil Rosch
Old Harbor Consulting
M/V "Curmudgeon" MT44 TC
Currently lying Bond Creek, NC

<<However, if you are in the habit of always anchoring out and always
charging from a motor driven alternator, the picture alters for the
worse. Chances are you never fully  saturate the battery plates with a
full charge. >>

Arild,
The answer to your connundrum is to go for a cruise!  8-10 hours on the
alternator should fully charge most battery banks, as long as the regulator
is properly set.  Speaking of which, several people have asked me for a
source for the manually adjustable regulator I use.

The regulator is an AMP-R14HD, which uses the large size output transistor
(TO-3?)  to easily power two 130 amp small-frame alternators.  There's a
tiny adjustment screw under the cover to set the voltage to any point
between 13.2 and 15.5 (approximately).  This setup works best, of course, if
you mount the regulator in a convenient place outside the engine room, next
to your digital voltmeter readout.  The source I found is Great-Water, Inc.,
in Maine.  1-866-209-6132.  Price $43.60 plus shipping.  No connection.

Mark Richter,  m/v Winnie the Pooh
Mark's Mobile Marine
Ortona, FL

-----Original Message-----
Arild,
The answer to your connundrum is to go for a cruise!  8-10 hours on the
alternator should fully charge most battery banks, as long as the
regulator is properly set.

REPLY
I know that and tell my clients as much.
However there are also a lot of people who figure on cruising south to
lotus land and hanging on the hook for a month as cheap dockage.
These are the people who end up with abused and sulfated battery banks
unless they take precautions and install the correct system to begin
with.

Mark writes:
Speaking of which, several people have asked me for a source for the
manually adjustable regulator I use. The regulator is an AMP-R14HD,
which uses the large size output transistor
(TO-3?)  to easily power two 130 amp small-frame alternators.  There's a
tiny adjustment screw under the cover to set the voltage to any point
between 13.2 and 15.5 (approximately). This setup works best, of course,
if you mount the regulator in a convenient place outside the engine
room, next to your digital voltmeter readout.  The source I found is
Great-Water, Inc., in Maine.  1-866-209-6132.  Price $43.60 plus
shipping.  No connection.

REPLY
Good idea. As a matter of fact, my Ford truck with a 120A L-N alternator
has a $12 regulator which is also adjustable with a tiny trim pot. These
external mounted regulators are standard in Fords.
The wife's Lincoln has the same regulator on the stock 80Amp alternator.

Arild