I was a a tradeshow where I saw one of the tiny Fischer Panda DC generators
with variable rpm. Nice and (much) too expensive for me, but I am thinking
of putting something like it together myself so I was quite interested in
their implementation.

I spoke with the guy doing the demo and he told me they vary the RPM from
2200 to 2800 only. Seems to me that doesn't make a lot of sense, because I
don't think the extra fuel consumption between idle @ 2200 and idle @ 2800
would be worth the effort of putting in the control circuitry?

I could also hear the little generator increase its rpm substantially above
its minimum when producing only 10A @ 24v, so I wonder if, in practice, you
would get ANY benefit from the variable RPM, because I think most would
shut the generator down when battery charging was down to only 10A. I also
wonder why they feel the need to increase RPM at all at that load since
just controlling the alternator excitation would surely get you 10A at 2200
rpm.

So does anybody understand their choices? Vibration, noise perhaps? Or is
this whole variable rpm implementation of Fischer Panda nothing but a
marketing ploy???

Greetings,

Frank

wrote in :

I could also hear the little generator increase its rpm substantially
above its minimum when producing only 10A @ 24v, so I wonder if, in
practice, you would get ANY benefit from the variable RPM, because I
think most would shut the generator down when battery charging was
down to only 10A. I also wonder why they feel the need to increase RPM
at all at that load since just controlling the alternator excitation
would surely get you 10A at 2200 rpm.


http://www.youtube.com/watch?v=zeBlxjL5dT8

This is a much better solution. It turns 300 RPM and this is the noise
it makes OUT IN THE OPEN WITHIN 6" OF A VIDEO CAMERA MICROPHONE. Notice
how the chickens are totally unafraid of it. It is producing 6,500
watts of 220VAC 50Hz serious electrical power, 24/7 for about a litre
per hour. Watch him put his hands on it. It's barely warm to the
touch. It has no water pump. Water circulates by convection to cool
it. The hot water pipe he touches doesn't burn his hands. A simple
heat exchanger with AC powered pump on the seawater side would cool it
forever, OR you could simply run some pipes through the hull and let it
convection cool through a keel cooler at its same level so convection
works...just under the waterline, eliminating the pumps entirely! They
run 24/7 for 40 years without overhaul. It will also run, flawlessly,
on any waste vegetable oil thin enough to inject. Preheat the oil by
wrapping copper tubing around the exhaust pipe and it runs for free.
Some owners have installed a ring gear and starter on one of the two
flywheels to automate the manual starting without even opening the
compression release. There is a youtube showing him starting it by
pressing a button.

Sailboat's can be easily powered by speed-controlled AC motors. Remove
the troublesome auxiliary diesels in them now, and replace it with a
listeroid and AC traction motor with solid state speed control. Run the
whole boat off AC power, not DC. The weight savings in batteries will
make up for the Listeroids weight in the bilge. No battery explosions
or leaking, no battery expenses, no battery maintenance and
replacements, no stupid DC power nonsense. All that heavy DC wiring can
be removed and replaced with high voltage AC much thinner and lighter
wiring, raising the waterline further. No charger will be necessary as
everything is AC powered, just like home. No inverters and that
nonsense, either.

Yankees will appreciate it when you simply move two Y valves and divert
the little waste heat from the heat exchanger to the hot water tank or
to the passive radiator heating inside the cold, cold cabin, extending
the boating season by many weeks each year. Southerners will appreciate
having the air conditioner running any time they get hot....not just at
the dock.

Did I mention it burns 1 litre an hour!

Screw all that low voltage, high current, DC crap.... Run the boat
electronic gadgets off a DC power supply with a little battery backup,
for emergencies like flooding. The Listeroid, by the way, WILL RUN
SUBMERGED as long as you keep the air intake above the waterline! I'd
suspect the flywheels to absorb a lot of power submerged, but it has
been done with no damage!

Can you imagine how quiet a Listeroid will be in a properly sound
proofed engine room with proper water box muffler to take care of the
popping? You might hear a faint thumping through the huge rubber shock
absorbers. No rigid motor mounts are necessary as it doesn't hook to
the shaft the traction motor drives.....electrically!

Not enough power? Install the 2-cylinder, 24hp model. It uses 2 litres
per hour! 12KW should be enough for any boat!

If you run it constantly, by the way, the oil change interval is twice a
month... It also has no oil pump to fail. It's splash oiled.

SO SIMPLE AN ENGINE!

That Chinese crap has a runtime life of about 500 hours....then they are
worn out.

Gogarty wrote in
:

If I recall (don't have a catalog here right now) Harbor Freight has
several portable generators at very low prices that coukld be adapted
to marine use.




Harbor Freight has a very nice ball bearing 10KW alternator for $300,
Chinese made. It's so smooth you can turn it with your fingers. The end
has two outlets and a voltmeter. RPM is your problem. Just mount it next
to your Yanmar and double belt drive it....(c;

On Sun, 28 Sep 2008 18:18:46 +0200, wrote:

I was a a tradeshow where I saw one of the tiny Fischer Panda DC generators
with variable rpm. Nice and (much) too expensive for me, but I am thinking
of putting something like it together myself so I was quite interested in
their implementation.

I spoke with the guy doing the demo and he told me they vary the RPM from
2200 to 2800 only. Seems to me that doesn't make a lot of sense, because I
don't think the extra fuel consumption between idle @ 2200 and idle @ 2800
would be worth the effort of putting in the control circuitry?

I could also hear the little generator increase its rpm substantially above
its minimum when producing only 10A @ 24v, so I wonder if, in practice, you
would get ANY benefit from the variable RPM, because I think most would
shut the generator down when battery charging was down to only 10A. I also
wonder why they feel the need to increase RPM at all at that load since
just controlling the alternator excitation would surely get you 10A at 2200
rpm.

So does anybody understand their choices? Vibration, noise perhaps? Or is
this whole variable rpm implementation of Fischer Panda nothing but a
marketing ploy???

Greetings,

Frank


I know nothing of this gen set. But I can understand the design
trades in question.
Start with this design approach:
low idle speed at no [electrical] load.
Go to max revs at max [electrical] load.

This strategy offers economical loiter (but with the possibility of
coking up a small engine) and a LONG latency to rated load supply.

Instead, idle at relatively high speed. This gives increased idle
consumption, but
1) reduced latency time to supplying max load
2) reduced output dip because there is more flywheel energy available
for the initial surge.

Brian W Altus OK

On Sun, 28 Sep 2008 17:01:32 +0000, Larry wrote:
... It is producing 6,500
watts of 220VAC 50Hz serious electrical power, 24/7 for about a litre
per hour. ...

6500 W / 746 W/HP = 8.7 HP at [say] 0.5 lb per HP hr = 4.3 lb/hr
If a US gal of gasoline weighs about 6.5 lb (it varies) that would be
over half a gallon an hour.

Still, a useful tip...

Brian W

Brian Whatcott wrote in
:

Still, a useful tip...



It's time the boats went diesel-electric. Sure works great for the
trains...(c;

On Tue, 30 Sep 2008 20:05:12 +0000, Larry wrote:

Brian Whatcott wrote in
:

Still, a useful tip...



It's time the boats went diesel-electric. Sure works great for the
trains...(c;

How about direct drive as used by the WWII German torpedo boats? You
stop the engine and restart it turning the other way. They didn't have
a compressor and only had enough air to start the engines once. Put a
premium on seamanship to say the least. All the biggest ships, tankers
and boxboats both, are that way. They avoid having a multimillion buck
gearbox. As for diesel-electric, all the Holland-America cruise ships
have it. One of the ones I was on had five engines for two shafts.
That way you can overhaul one and run on four easily. I saw them
loading cylinder heads at the start of a trip. All their ships have a
bar directly above the wheelhouse, with floor to ceiling glass on all
three outside walls. Great in a Norwegian or Alaskan fjord, or in a
harbor.

Casady

"Richard Casady" wrote in message
...
On Tue, 30 Sep 2008 20:05:12 +0000, Larry wrote:

Brian Whatcott wrote in
m:

Still, a useful tip...



It's time the boats went diesel-electric. Sure works great for the
trains...(c;

How about direct drive as used by the WWII German torpedo boats? You
stop the engine and restart it turning the other way. They didn't have
a compressor and only had enough air to start the engines once. Put a
premium on seamanship to say the least. All the biggest ships, tankers
and boxboats both, are that way. They avoid having a multimillion buck
gearbox.

'Multi-million gearbox'?
Have you ever looked at an engine that will turn a big ships propeller at
80-100 rpm with direct drive?
They do not come cheap.

(Richard Casady) wrote in
:

How about direct drive as used by the WWII German torpedo boats? You
stop the engine and restart it turning the other way. They didn't have
a compressor and only had enough air to start the engines once. Put a
premium on seamanship to say the least. All the biggest ships, tankers
and boxboats both, are that way. They avoid having a multimillion buck
gearbox. As for diesel-electric, all the Holland-America cruise ships
have it. One of the ones I was on had five engines for two shafts.
That way you can overhaul one and run on four easily. I saw them
loading cylinder heads at the start of a trip. All their ships have a
bar directly above the wheelhouse, with floor to ceiling glass on all
three outside walls. Great in a Norwegian or Alaskan fjord, or in a
harbor.

Casady



My concept for diesel-electric stems from the boaters' tremendous need
for electrical power for an ever-increasing array of electrical gadgets
far exceeding low voltage DC's ability to provide it. This need exceeds
the need for propulsion 95% of the time, the propulsion only used to get
in and out of the dock in real sailboats. So, it simply makes sense to
remove the 5%-used, directly coupled propulsion engine that doesn't
provide real electrical power and replace it with a real genset that
does. Now having real electrical power aboard, high voltage AC to match
real loads, it's simply a matter of providing the driveshaft solid-state
speed controlled, high voltage AC traction motors, just like trains have
been using for decades, to drive the boat in and out that other 5% of
use.

It simply makes better sense.....

To make machinery noise much more tolerable to the inhabitants, we must
do away with the high revolution prime movers of this electrical system
and, instead, use very primative, very slow turning diesels, which have
a very long history of amazingly long MTBF (mean time between failures),
very low maintenance (just change the oil a couple of times a month for
24 hour service), with a minimal number of moving parts (Listeroids have
12). Now disconnected from the drive shaft and its constant alignment
problems, engines and alternators can be put on a horizontal, not
slanted, subframe with intensive use of soft rubber mounts between the
engines and the frame and the frame and the boat. This is exactly why
the interior diesel and mechanical noises heard by passengers of a
Mercedes Benz diesel sedan are so low. There are two levels of dampers
between the body and the engine and one layer of dampers between the
body and the suspension system. Add soft mounting to extensive sound
absorbing materials, with tight controls on penetration of the
materials, and you have a very quiet diesel power plant anyone can live
with except, of course, the sailing hermits, who are not a major part of
the customers.

A lot of the propulsion noise you hear in a boat is transmitted by rigid
engine mounts to keep it aligned which are marginal dampers and through
the shaft to hull bearings, themselves. Diesel-electric eliminates
both.

On Wed, 1 Oct 2008 11:31:27 +0200, "Edgar"
wrote:


"Richard Casady" wrote in message
.. .
On Tue, 30 Sep 2008 20:05:12 +0000, Larry wrote:

Brian Whatcott wrote in
:

Still, a useful tip...



It's time the boats went diesel-electric. Sure works great for the
trains...(c;

How about direct drive as used by the WWII German torpedo boats? You
stop the engine and restart it turning the other way. They didn't have
a compressor and only had enough air to start the engines once. Put a
premium on seamanship to say the least. All the biggest ships, tankers
and boxboats both, are that way. They avoid having a multimillion buck
gearbox.

'Multi-million gearbox'?
Have you ever looked at an engine that will turn a big ships propeller at
80-100 rpm with direct drive?
They do not come cheap.


It seems to be more a matter of size as the BIG engines are all low
RPM engines that at lower RPM while lower power engines are usually
higher speed engines. for example, the Emma Mursk uses a 108,920 H.P.
@ 102 RPM engine and probably doesn't require a reduction gear, while
a smaller ship might use a 5,800 Hp @ 600 RPM engine with reduction
gear.

Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)