On Mon, 06 Jun 2005 13:41:50 -0400, rhys wrote:

On Thu, 02 Jun 2005 13:27:27 -0400,
wrote:


The problem with the STI system is the size of the battery pack
required for the 144 volt system. It takes up a lot of space and adds
a lot of weight. There are a lot of advantages to their system as
well, especially as was already noted the regeneration under sail
appeals for long passagemaking.

Hopefully as the technology evolves a better and lighter battery
system will be brought online. As a lover of multihulls, the current
battery system takes their system off the table for me.

I can see that with a multihull. My current boat wouldn't enjoy 12
batteries, all that copper and the required charger, either, But
certainly there are passagemakers and full keelers that could have the
batteries low and in return shrink the size of the diesel tanks to
whatever would reasonably cope with the genset's occasional use.

I also anticipate a lot of competition in this area, which I hope will
spur further savings in weight and complexity.

R.
I agree. I think STI is a good first offering that will be built on by
others in the near future. I am not sure what the benefits are of
using the 144 volt motor vs a 24 or 48 volt system. I use an electric
truck at work that does quite well on a 48 volt system and have
wondered if someone will follow up and offer a system that can use a
more practical sized battery system.


Weebles Wobble
(but they don't fall down)

Well. I am a real fan of eletric motors for boats. And while the distance I
travel on the lake the to and from my cabin is not that great (about 2.5
kilometers per trip) I got sick and tried of the old two stroke and the work
needed to get it going. On very cold days, it could be murder to start - and
let's not mention the mess-ups in oil ratios when my brother tried to use it
a few times.

The four stroke honda works great as long as I don't do something stupid and
end up flooding the engine, then it takes up to 15 minutes before it will
start. Atleast I finally learnt how to flush the water filter.

The electric motors - perfect first, perfect always. Generally I get about 4
trips out of the main battery (I have a smaller backup incase) and if I
remember to plug in the main batteries from the cabin to recharge boat's
battery before I go to sleep, it is always ready in the morning.

To me however the biggest advantage is the quiet. Set at lower speeds the
motors as so quiet that even beavers which are in the water and would notice
an loud sound do not hear me coming. I can visit the loon's nest without
driving the parent birds away, I get far closer to animals on shore with the
electric than even with paddles.

-----------------------------------------------------------------------------------------------------------------------------------------------------

When talking about long distance travel well designed electric systems have
an advantage I did not see mentioned here. The ability to instantly switch
between motor vs generator lets you do a special type of cruising called
‘regenerative motor sailing'.

Basicy, you set the controller for a fixed speed and start sailing. If the
speed is even a small faction below the average speed your boat would in the
wind conditions then the batteries are almost always in a charging state -
more importantly. If the wind increase/gusts the energy is shuttled to the
batteries instead of trying to speed up the boat to a speed it can not keep -
so you sail on at a steady rate. The wind dies a bit and the motor mode
instantly keeps your speed up - so you sail on at a steady rate. Your boat
starts to surf down a wave - again the generator mode kicks in and the extra
energy goes into the battries - so you sail on at a steady rate. You hit the
face of the wave and you start to climb up and once again the motor mode
kicks in - so you sail on at a steady rate.

Get the idea Infact Multihull magazine reports on once setting the right
speed for ‘regenerative motor sailing' all day, enjoying it because it was
so smooth and quiet and still ending the day with more of a charge in the
batteries than when they started out.

Earl Colby Pottinger

http://www.multihull-maven.com/article.php?id=40
http://www.multihull.com/elec_wheel.html
http://www.solomontechnologies.com/news.htm

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Ted tedwilliams@nospam :


Hmmm, the math is pretty simple. We measure the output power of motors or
engines in Hp. 1 Hp = 746 watts. 5 Hp = 3730 watts. To produce 5 Hp at 12
volts would require 310.8 amps. (Assuming no IR, friction, and windage
losses) That requires some pretty heavy duty wiring. I doubt that I could
lift a true 5 Hp 12 volt motor.

50 amps at 12 volts = 600 watts or 0.804 Hp. That is the maximum Hp
produced
by the T47. Again, no IR, friction, and windage losses which is impossible
to achieve. With a good motor, you might get 90% out of what you put in.

I think you made a mistake, don't ST motors run at 144 volts? That makes a
big diffirence.

check out:
http://www.solomontechnologies.com/S...%20system.html

Earl Colby Pottinger

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On Fri, 10 Jun 2005 01:58:55 -0500,
Earl Colby Pottinger wrote:
When talking about long distance travel well designed electric systems have
an advantage I did not see mentioned here. The ability to instantly switch
between motor vs generator lets you do a special type of cruising called
‘regenerative motor sailing'.

Basicy, you set the controller for a fixed speed and start sailing. If the
speed is even a small faction below the average speed your boat would in the
wind conditions then the batteries are almost always in a charging state -
more importantly. If the wind increase/gusts the energy is shuttled to the
batteries instead of trying to speed up the boat to a speed it can not keep -
so you sail on at a steady rate. The wind dies a bit and the motor mode
instantly keeps your speed up - so you sail on at a steady rate. Your boat
starts to surf down a wave - again the generator mode kicks in and the extra
energy goes into the battries - so you sail on at a steady rate. You hit the
face of the wave and you start to climb up and once again the motor mode
kicks in - so you sail on at a steady rate.

Get the idea Infact Multihull magazine reports on once setting the right
speed for ‘regenerative motor sailing' all day, enjoying it because it was
so smooth and quiet and still ending the day with more of a charge in the
batteries than when they started out.

Earl Colby Pottinger

http://www.multihull-maven.com/article.php?id=40
http://www.multihull.com/elec_wheel.html
http://www.solomontechnologies.com/news.htm




Thanks for the links.

We are looking at having to repower Windwalker (aging Perkins 107) in
the next couple of years. I don't think that electric is *quite* there
yet, for us, but it's not as far off as it used to be, that's for sure.

If the fuel cells using diesel or methanol were available at a decent
price, that would tip it over the edge for me. I'd dearly love to get
rid of the stinky "iron genny" and getting quiet, and a good recharger
for house batteries whilst underway is a bonus. Plus, even with the
weight of the batteries, I'd likely wind up losing weight by dumping the
diesel engine.

Solomon has some nice rigs, but a bit pricey at the moment. Getting
there though.

--
Jim Richardson http://www.eskimo.com/~warlock
Gun exchange programs would work great if they gave you a gun when you
handed in a criminal

Ted tedwilliams@nospam :

Every motor becomes a generator when the motor is turned faster than the
rated speed at the rated EMF. This is commonly known as regeneration.

The point is that ST motors are designed to be efficent generators when used
in that mode, and that the circuits that are to be included are design to use
those motors as a source of power when the motor goes into generator mode.

Secondly, if the motor is running in extended range (not possible with
permanent magnet motors) you increase the motor speed by holding armature
volts constant and decreasing the motor field flux. This is known as the
constant Hp mode of operation since as speed increase, the resultant torque
decrease proportionatly thus constant Hp.

Yes, but ST's circuits that they use take gotcha's like this into account, no
matter what speed the motors are used at as generator and not matter what the
voltage/ampage output of the motor/generator the invertor in designed to
convert it to the best range for recharging the batteries.

The motors are not directly connected to the batteries which could result in
the type of problem you relate above. Rather a very intelligent speed
controller with feedback from the motors. If the motors are spinning too
slow indicating that the boat moving slowly the power to the motors are
ramped up. If the motors are spinning too fast thus indicating the boat is
also moving faster than the set speed the motors are used as generators the
resulting power is *conditioned* to the best values to recharge the batteries.

Earl Colby Pottinger

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Jim Richardson :

If the fuel cells using diesel or methanol were available at a decent
price, that would tip it over the edge for me. I'd dearly love to get
rid of the stinky "iron genny" and getting quiet, and a good recharger
for house batteries whilst underway is a bonus. Plus, even with the
weight of the batteries, I'd likely wind up losing weight by dumping the
diesel engine.

Have you looked at Honda's generators with invertor output?

For the power out, those machine are very quiet. While the largest model I
have used is only 2.5KW it is my understanding that all the models are very
quiet in operation. More than once I had to personally go and check my unit
to see if it ran out of gas because I could not hear it running. And that is
another thing, depending on your needs the ecomo mode uses very little gas to
run. Let's me set my charger to slow charge the batteries (best for life and
completeness of charge) without wasting gas producing more power than is used.

Earl Colby Pottinger


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I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
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