I may even have it from somewhere before, but the recent conversations on
reefers brought it to mind:

Someone on these lists built a direct drive 12V compressor for
refrigeration. My recollection has it connected to cold plates. It was
designed to do what an engine drive would do, but not run the engine. At
the time I saw it, it was new. If they're reading, I'd be interested to see
a report on its efficacy.

How much power did/does it take to operate? Was the size of the compressor
notably less than one on the engine, and if so, what is the relative run
time? In the end, are you happy with the outcome? If not, or even so, is
there anything you'd have done differently if you were doing it again?

Thanks.

L8R

Skip (and Lydia, by proxy), thinking of how to use the lovely cooling system
on the boat without running the engine or the AC air-cooled system, either

--
Morgan 461 #2
SV Flying Pig
http://tinyurl.com/384p2

"And then again, when you sit at the helm of your little ship on a
clear night, and gaze at the countless stars overhead, and realize
that you are quite alone on a great, wide sea, it is apt to occur to
you that in the general scheme of things you are merely an
insignificant speck on the surface of the ocean; and are not nearly
so important or as self-sufficient as you thought you were. Which is
an exceedingly wholesome thought, and one that may effect a
permanent change in your deportment that will be greatly appreciated
by your friends." - James S. Pitkin

Skip,
Some basics: First divide marine refrigeration into two classes, engine
driven and electric. Engine driven systems on sailboats are always
holding plate systems. The compressor can process a lot of BTUs in a
short time while the engine is also charging batteries or propelling the
boat which makes them very efficient. They are great if you are on board
most of the time and the alternator is your primary battery recharging
system. You can freeze the plates as you charge and/or motor. The down
side is that you can't leave the boat for more than a couple of days to
explore an island and box temps tend to oscillate.

Electrically powered systems have one primary advantage: with good
controls, shore power, a lot of solar panels or a wind generator and
lots of wind they can be made to operate unattended. This can be a
distinct advantage if you are off the boat for more than a day or two.

They can be further divided into AC and DC systems. AC systems are
usually a motor driving either an automotive or small commercial
compressor either directly or through a belt. They are closely akin to
engine driven in that they normally use a holding plate and can freeze
the plates almost as fast but away from shore power the engine usually
must be running to generate the power needed to run the motor which
means it has the same limitations plus not being quite as efficient away
from shore power due to losses in the alternator, battery charging and
inverter.

DC systems can be divided further into holding plate and evaporator
systems and the compressors into discrete compressor/motor assemblies or
hermetically sealed compressors. The discrete compressors are similar
to the AC system being linked to the motor either directly or via a belt
and usually freezing a holding plate. There is a practical limit to DC
of 1 1/2 HP motor so they are not as powerful as AC or engine drives.
They also tend to be noisy.

Hermetic DC systems usually drive an evaporator and are more closely kin
to a domestic refrigerator. Most are based on one of the Danfoss
compressors which are gradually getting more efficient. They cycle on
and off all the time and will therefore maintain a more constant box
temperature and, with solar panels or other alternate charging source
can operate constantly while the boat is not in use but they can consume
20% to 40% more energy.



Skip Gundlach wrote:

I may even have it from somewhere before, but the recent conversations on
reefers brought it to mind:

Someone on these lists built a direct drive 12V compressor for
refrigeration. My recollection has it connected to cold plates. It was
designed to do what an engine drive would do, but not run the engine. At
the time I saw it, it was new. If they're reading, I'd be interested to see
a report on its efficacy.

How much power did/does it take to operate? Was the size of the compressor
notably less than one on the engine, and if so, what is the relative run
time? In the end, are you happy with the outcome? If not, or even so, is
there anything you'd have done differently if you were doing it again?

Thanks.

L8R

Skip (and Lydia, by proxy), thinking of how to use the lovely cooling system
on the boat without running the engine or the AC air-cooled system, either


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Now, with the basics out of the way, MHO: This is not a good idea. It
looks like the worst of both worlds. 12VDC hermetic compressors are
pretty well limited to 1/4 HP or less. That will take a looong time at
full power to freeze a decent size holding plate. Several makers of
hermetic systems do offer holding plates but strongly discourage their use.

Skip Gundlach wrote:

I may even have it from somewhere before, but the recent conversations on
reefers brought it to mind:

Someone on these lists built a direct drive 12V compressor for
refrigeration. My recollection has it connected to cold plates. It was
designed to do what an engine drive would do, but not run the engine. At
the time I saw it, it was new. If they're reading, I'd be interested to see
a report on its efficacy.

How much power did/does it take to operate? Was the size of the compressor
notably less than one on the engine, and if so, what is the relative run
time? In the end, are you happy with the outcome? If not, or even so, is
there anything you'd have done differently if you were doing it again?

Thanks.

L8R

Skip (and Lydia, by proxy), thinking of how to use the lovely cooling system
on the boat without running the engine or the AC air-cooled system, either


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

I have a 12V DC belt driven setup. Based upon the size of the
pulley on the motor and compressor, a direct drive system
would seem to be rather tricky. My motor and compressor are
both 3/4 HP. Draws 50A when running.

Doug
s/v Callista

"Skip Gundlach" wrote in
message ...
I may even have it from somewhere before, but the recent conversations on
reefers brought it to mind:

Someone on these lists built a direct drive 12V compressor for
refrigeration. My recollection has it connected to cold plates. It was
designed to do what an engine drive would do, but not run the engine. At
the time I saw it, it was new. If they're reading, I'd be interested to
see
a report on its efficacy.

How much power did/does it take to operate? Was the size of the
compressor
notably less than one on the engine, and if so, what is the relative run
time? In the end, are you happy with the outcome? If not, or even so, is
there anything you'd have done differently if you were doing it again?

Thanks.

L8R

Skip (and Lydia, by proxy), thinking of how to use the lovely cooling
system
on the boat without running the engine or the AC air-cooled system, either

--
Morgan 461 #2
SV Flying Pig
http://tinyurl.com/384p2

"And then again, when you sit at the helm of your little ship on a
clear night, and gaze at the countless stars overhead, and realize
that you are quite alone on a great, wide sea, it is apt to occur to
you that in the general scheme of things you are merely an
insignificant speck on the surface of the ocean; and are not nearly
so important or as self-sufficient as you thought you were. Which is
an exceedingly wholesome thought, and one that may effect a
permanent change in your deportment that will be greatly appreciated
by your friends." - James S. Pitkin

The new Glacier Bay system uses a hermetic Danfoss (pretty sure
it is a Danfoss) compressor with cold plates. From what I can gather it
works very well. Can even power a 6000BTU air conditioner as well.

Doug
s/v Callista

"Glenn Ashmore" wrote in message
news:mV%Ec.54$jp1.21@lakeread04...
Now, with the basics out of the way, MHO: This is not a good idea. It
looks like the worst of both worlds. 12VDC hermetic compressors are
pretty well limited to 1/4 HP or less. That will take a looong time at
full power to freeze a decent size holding plate. Several makers of
hermetic systems do offer holding plates but strongly discourage their
use.

Skip Gundlach wrote:

I may even have it from somewhere before, but the recent conversations
on
reefers brought it to mind:

Someone on these lists built a direct drive 12V compressor for
refrigeration. My recollection has it connected to cold plates. It was
designed to do what an engine drive would do, but not run the engine.
At
the time I saw it, it was new. If they're reading, I'd be interested to
see
a report on its efficacy.

How much power did/does it take to operate? Was the size of the
compressor
notably less than one on the engine, and if so, what is the relative run
time? In the end, are you happy with the outcome? If not, or even so,
is
there anything you'd have done differently if you were doing it again?

Thanks.

L8R

Skip (and Lydia, by proxy), thinking of how to use the lovely cooling
system
on the boat without running the engine or the AC air-cooled system,
either


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Hi, Doug, and thanks for the bounce.

"Doug Dotson" wrote in message
...
I have a 12V DC belt driven setup. Based upon the size of the

The one I had in mind (I saw pix of the setup, mounted on a breadboard; the
shaft went directly to the compressor) was direct, not belt, driven.

pulley on the motor and compressor, a direct drive system
would seem to be rather tricky. My motor and compressor are
both 3/4 HP. Draws 50A when running.

50A is a *BIG* load. How long does it run per cycle, and per day,
typically? And, does that include the water pump, or is that an additional
load?

Another alternative I've seen, though it's a bit of an around-the-barn
approach unless one is hooked up to shore power (recall from other
discussions I really don't want to be running engines, whether propulsion or
generator if I don't have to, and this would require an inverter). That's a
washing machine or other similarly cheaply acquired motor with appropriately
geared pulley driving the engine-driven compressor which has been set up
with two/double pulleys and a means of quick-change on attitude so as to
relieve the engine belt and engage the AC belt. You get the same output as
with the engine but without running it. Ideal, perhaps for marina dwellers,
but perhaps a bit of a kludge for everyday cruisers on the hook for days at
a time, but not really long term. That, of course plus the accumulated draw
with the inverter and pumps might be in the same ballpark as yours...

L8R

Skip

--
Morgan 461 #2
SV Flying Pig
http://tinyurl.com/384p2

"And then again, when you sit at the helm of your little ship on a
clear night, and gaze at the countless stars overhead, and realize
that you are quite alone on a great, wide sea, it is apt to occur to
you that in the general scheme of things you are merely an
insignificant speck on the surface of the ocean; and are not nearly
so important or as self-sufficient as you thought you were. Which is
an exceedingly wholesome thought, and one that may effect a
permanent change in your deportment that will be greatly appreciated
by your friends." - James S. Pitkin

I have to hand it to Kevin. He can squeeze out more heat with less amps
than anybody else in the business but the bleeding edge comes at a price.

That GB compressor does look sort of like a BD50 but I just can't
imagine Kevin lowering himself to that. :-) Actually the compressor has
some subtle physical differences that make some big differences in
efficiency and he has licenced the production to one of the biggies like
Tecumseh or somebody. The other main difference is the recovery system
that sucks the last bit of heat out of the refirgerant. The numbers
look impressive but so does the price.

Doug Dotson wrote:

The new Glacier Bay system uses a hermetic Danfoss (pretty sure
it is a Danfoss) compressor with cold plates. From what I can gather it
works very well. Can even power a 6000BTU air conditioner as well.

Doug
s/v Callista

"Glenn Ashmore" wrote in message
news:mV%Ec.54$jp1.21@lakeread04...

Now, with the basics out of the way, MHO: This is not a good idea. It
looks like the worst of both worlds. 12VDC hermetic compressors are
pretty well limited to 1/4 HP or less. That will take a looong time at
full power to freeze a decent size holding plate. Several makers of
hermetic systems do offer holding plates but strongly discourage their

use.

Skip Gundlach wrote:


I may even have it from somewhere before, but the recent conversations

on

reefers brought it to mind:

Someone on these lists built a direct drive 12V compressor for
refrigeration. My recollection has it connected to cold plates. It was
designed to do what an engine drive would do, but not run the engine.

At

the time I saw it, it was new. If they're reading, I'd be interested to

see

a report on its efficacy.

How much power did/does it take to operate? Was the size of the

compressor

notably less than one on the engine, and if so, what is the relative run
time? In the end, are you happy with the outcome? If not, or even so,

is

there anything you'd have done differently if you were doing it again?

Thanks.

L8R

Skip (and Lydia, by proxy), thinking of how to use the lovely cooling

system

on the boat without running the engine or the AC air-cooled system,

either

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com





--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

It surely is expensive.

"Glenn Ashmore" wrote in message
news:vo3Fc.249$jp1.15@lakeread04...
I have to hand it to Kevin. He can squeeze out more heat with less amps
than anybody else in the business but the bleeding edge comes at a price.

That GB compressor does look sort of like a BD50 but I just can't
imagine Kevin lowering himself to that. :-) Actually the compressor has
some subtle physical differences that make some big differences in
efficiency and he has licenced the production to one of the biggies like
Tecumseh or somebody. The other main difference is the recovery system
that sucks the last bit of heat out of the refirgerant. The numbers
look impressive but so does the price.

Doug Dotson wrote:

The new Glacier Bay system uses a hermetic Danfoss (pretty sure
it is a Danfoss) compressor with cold plates. From what I can gather it
works very well. Can even power a 6000BTU air conditioner as well.

Doug
s/v Callista

"Glenn Ashmore" wrote in message
news:mV%Ec.54$jp1.21@lakeread04...

Now, with the basics out of the way, MHO: This is not a good idea. It
looks like the worst of both worlds. 12VDC hermetic compressors are
pretty well limited to 1/4 HP or less. That will take a looong time at
full power to freeze a decent size holding plate. Several makers of
hermetic systems do offer holding plates but strongly discourage their

use.

Skip Gundlach wrote:


I may even have it from somewhere before, but the recent conversations

on

reefers brought it to mind:

Someone on these lists built a direct drive 12V compressor for
refrigeration. My recollection has it connected to cold plates. It
was
designed to do what an engine drive would do, but not run the engine.

At

the time I saw it, it was new. If they're reading, I'd be interested
to

see

a report on its efficacy.

How much power did/does it take to operate? Was the size of the

compressor

notably less than one on the engine, and if so, what is the relative
run
time? In the end, are you happy with the outcome? If not, or even so,

is

there anything you'd have done differently if you were doing it again?

Thanks.

L8R

Skip (and Lydia, by proxy), thinking of how to use the lovely cooling

system

on the boat without running the engine or the AC air-cooled system,

either

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com





--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Skip,

Comments below.

Doug
s/v Callista

"Skip Gundlach" wrote in
message ...
Hi, Doug, and thanks for the bounce.

"Doug Dotson" wrote in message
...
I have a 12V DC belt driven setup. Based upon the size of the

The one I had in mind (I saw pix of the setup, mounted on a breadboard;
the
shaft went directly to the compressor) was direct, not belt, driven.

I understand that. It is just that a 1:1 coupling would seem not to be
able to drive the compressor at it's most efficent speed. That is just
my gut feeling based upon my experience which is not extensive by
any stretch. I believe my motor runs at 1800 RPM. The pully on the
motor is maybe 3 inches in diameter and the one on the compressor
is perhaps 10 inches. It requires alot of torque to spin a 3/4 HP
compressor under full load.

pulley on the motor and compressor, a direct drive system
would seem to be rather tricky. My motor and compressor are
both 3/4 HP. Draws 50A when running.

50A is a *BIG* load. How long does it run per cycle, and per day,
typically? And, does that include the water pump, or is that an
additional
load?

When on ships power I run it twice per day. Once in the morning and once in
the
afternoon. It generally runs about 40-45 minutes to freeze the plates. This
is
the most efficient mode. When plugged into shorepower, I allow it to
run automatically with a thermostat controlling everything. It runs longer
in terms of total running time since the first 5 minutes or so of running
time doesn;t actually cool much. It generally kicks in every couple of hours
for 15 minutes or so. This is supportting a 9 cu-ft freezer box and a
12 cu-ft fridge box in a spillover arrangement. The water pump draws
a whopping half an amp I think.

Another alternative I've seen, though it's a bit of an around-the-barn
approach unless one is hooked up to shore power (recall from other
discussions I really don't want to be running engines, whether propulsion
or
generator if I don't have to, and this would require an inverter). That's
a
washing machine or other similarly cheaply acquired motor with
appropriately
geared pulley driving the engine-driven compressor which has been set up
with two/double pulleys and a means of quick-change on attitude so as to
relieve the engine belt and engage the AC belt. You get the same output
as
with the engine but without running it. Ideal, perhaps for marina
dwellers,
but perhaps a bit of a kludge for everyday cruisers on the hook for days
at
a time, but not really long term. That, of course plus the accumulated
draw
with the inverter and pumps might be in the same ballpark as yours...

That will work. Probably better to buy a small fridge at Home Depot if
one is in a marina most of the time.

L8R

Skip

--
Morgan 461 #2
SV Flying Pig
http://tinyurl.com/384p2

"And then again, when you sit at the helm of your little ship on a
clear night, and gaze at the countless stars overhead, and realize
that you are quite alone on a great, wide sea, it is apt to occur to
you that in the general scheme of things you are merely an
insignificant speck on the surface of the ocean; and are not nearly
so important or as self-sufficient as you thought you were. Which is
an exceedingly wholesome thought, and one that may effect a
permanent change in your deportment that will be greatly appreciated
by your friends." - James S. Pitkin

Skip:

Theoretical considerations aside, my advice would be to insulate your box to
the hilt and then install one of the many DC driven Danfoss compressor
systems with a direct evaporator coil, ie no holding plate. Alder Barbour
and others make them.

David