Advice on refridgeration unit please
 

On Sat, 19 Jul 2008 02:33:54 +0000, Larry wrote:

///
I was cruising on of my thrift shops today and paid $10 for a Sears
Kenmore 2.2 cu ft little bar fridge in nice condition.
///The little compressor is SO
quiet you can't even hear it start!

/// The
wattmeter still sits on 71W when it's running, which I take to be about
15% duty cycle on my stopwatch after the initial cooldown and
temperature stabilization to 38F on the top shelf away from the evap.
The thermometer inside the little box evap sits on 8F at about 2/3
thermostat setting and should keep the icecream hard...(c;

...I think the nice door on this fridge will fit
on my favorite old R-12 fridge, the one with the 40 watt vibrator
compressor from Sweden. That's the most efficient little fridge I own
...
I'll be in the lab with my Linux tablet running spreadsheets if Algore
calls for advise....

Forget about the pleasures of sailing a fresh warm breeze, it's
nice to see simple joy radiating off into the net: about finding a
bargain, running tech checks, looking forward to icecream
and chill beer afloat. Gotta love those dorm fridges.

Brian W

Advice on refridgeration unit please
 

On Jul 18, 8:00*pm, Larry wrote:
...
Would you drive a Nano for $2500 that gets 70 mpg?

Yup. I think the idea of saying that all vehicles below a certain
weight are motorcycles is brilliant. Let's allow folks to drive them
who have taken an extra course and are aware of the risks. I'm think
that tiny cars would be very popular in the big urban centers
particularly if they got HOV privileges & so on. What's the down side?

-- Tom.

Advice on refridgeration unit please
 

" wrote in news:1bbb3540-d522-4939-
:

When the batteries are
low I can throw a couple hundred amps at them for 15 minutes or so and
the absorption drops off pretty slowly.

200A x 12V = 2,400 watts.

No danger of overheating and warping AGM plates with only 2.4 kilowatts
forced into them at all. You should crank up the charging even further.

SARCASM OFF

If you ever get a chance to look around inside a sailboat where the battery
has exploded, don't miss this lesson in humility.

It's amazing how the middle spoons in a neat stack of "stainless" spoons is
pitted and eaten just like the ones on the ends, in a closed drawer,
outside the battery box, on the other side of the boat from the exploding
battery. Even the bellcrank on the rudder post had acid damage on it.

You gotta see it to become a believer.....

......and stop cooking lead acid batteries for life!

Advice on refridgeration unit please
 

Bruce in Bangkok wrote in
:

Suggestions: Think that Stephen is right. Seems senseless to run 12VDC
through inverter to power 220 VAC compressor. Always some losses in
this type of system. Believe that air cooled condenser makes more
sense as personal experience shows that 12 VDC air cooled system works
in tropical climate and eliminates all the problems associated with
the water cooling system - pumps, clogging, etc.



Does someone make a 12VDC compressor? I've never seen one, here. I do see
AC inverters built into fridges driving standard AC-powered compressors
that have relays or electronics to switch to shore power if shore power is
available to run the compressor straight off shore power, however.

Inversion and synthsized AC power creation from battery power is now in the
range of 98-99% efficient with switching power supply technology using
pulse-width-modulation to accomplish a near-perfect sinewave output to
drive loads. These powerful synthesizers are very cheaply constructed and
very profitable.

The AC compressors synchronize to power line frequency (50 or 60 Hz), which
gives them a steady power output regardless of condensor pressure loading
which would drive a DC motor crazy trying to maintain counter EMF.

It makes little difference in efficiency running a switching inverter
outside......or building one inside for another $1500 to sell at the boat
store. The price difference is phenomenal!

Advice on refridgeration unit please
 

Bruce in Bangkok wrote in
:

half the ozone hole all by
yourself :-(


.....an ozone hole that hasn't varied one iota from all of man's activities
since it was discovered?

Advice on refridgeration unit please
 

" wrote in news:b2f93b8e-4554-434c-
:

What's the down side?



Oil company profits.....for my president's family.

Advice on refridgeration unit please
 

On Jul 19, 2:32*pm, Larry wrote:
...
200A x 12V = 2,400 watts.

No danger of overheating and warping AGM plates with only 2.4 kilowatts
forced into them at all. *You should crank up the charging even further..
...

Just for the record, my electrical system was designed and installed
by Gary Pacey of Outback Marine. He's an EE specializing in marine
power systems. He's installed virtually the same system on lots of
boats. In the small world category, the boat three down the dock from
us was built in the same year in the same part of Oz and with the same
power system as my boat. I know Gary did a lot of in house testing and
had good relationships with the suppliers of the batteries and
controllers. In short, this isn't something that I just threw
together out of catalogs.

Also, I don't follow you point. Are you saying 2.4Kw is too much
power for any battery bank or were you making a specific point?

-- Tom.

Advice on refridgeration unit please
 

On Sat, 19 Jul 2008 09:43:01 -0700 (PDT), "
wrote:

On Jul 19, 12:23*am, Bruce in Bangkok
wrote:
...
During your bulk charging stage what voltage are your batteries
reading and how many amps are you charging at? ...

I generally cycle the batteries on passage where I try to get away
with one hour of charging a day. We support two 12 volt, air cooled
compressors (fridge and freezer) and the auto pilot and nav lights,
RADAR, radios &c. Our solar array is usually partially shaded while
under way so we have less input there.

Keeping in mind that no two days are alike and I'm not working off of
data logs or anything: In the morning we generally see ~12 volts or a
little less on the batteries (they are always under load) and the
acceptance rate plus load is more than 200 amps. The voltage rises
slowly to 14.2~14.4 (depending on what the temp is). After about and
hour I typically shut down the engine and the acceptance plus load at
14ish is in the low teens. For the first third or so of that the
charge rate is greater than 50 amps. My take is that I'd kill
standard sized alternators pretty fast asking them to go full out for
half an hour (integessing the extra time to 50 amps) plus another 45
min of topping off and it would take more time to get to the same
charge rate. Down the list a ways you mention a cat that charges its
batteries 3 hours a day. I would find that intolerable. It seems to
me that the trick to reducing charging time is to have a good sized
alternator and know when to stop charging. It's unusual to be
offshore for more than a week without a day of calms and on those days
you can top the battery off while getting a propulsion boost form the
motor. YMMV.

-- Tom.


No, Perhaps I should have explained in more detail. On the 4 day trip
because of having little wind the Cat motored between 3 - 4 hours a
day.

Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)

Advice on refridgeration unit please
 

On Sat, 19 Jul 2008 10:07:10 -0700, "Capt. JG"
wrote:

"Gordon" wrote in message
om...
Bruce in Bangkok wrote:

$1000 fridges my ass....


If you don;t stop going on about R-12 the tree hugging gestapo is
going to come calling and burn a cross on your lawn, or something. My
God man, you are probably responsible for half the ozone hole all by
yourself :-(


Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)

Watching a greenie show on TV last night and it showed an illustration of
the hole in the ozone layer. Their statement was that it was caused by man
but luckily it healed itself! HUH?
G


Not quite... didn't heal itself until after we stopped dumping the
refrigerant into the atmosphere.

http://www.livescience.com/environme...zone_hole.html
http://www.techmonitor.net/techmon/0...zo_science.htm


Since here in Thailand, and probably all over the third world, they
are happily using R-12, and dumping it to atmosphere it probably goes
to prove that the Americans were responsible.

Damn, if the Indians hadn't sold Manhattan Island we wouldn't have had
all these problems :-)
Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)

Advice on refridgeration unit please
 

On Sat, 19 Jul 2008 21:42:34 +0000, Larry wrote:

Bruce in Bangkok wrote in
:

Suggestions: Think that Stephen is right. Seems senseless to run 12VDC
through inverter to power 220 VAC compressor. Always some losses in
this type of system. Believe that air cooled condenser makes more
sense as personal experience shows that 12 VDC air cooled system works
in tropical climate and eliminates all the problems associated with
the water cooling system - pumps, clogging, etc.



Does someone make a 12VDC compressor? I've never seen one, here. I do see
AC inverters built into fridges driving standard AC-powered compressors
that have relays or electronics to switch to shore power if shore power is
available to run the compressor straight off shore power, however.

Inversion and synthsized AC power creation from battery power is now in the
range of 98-99% efficient with switching power supply technology using
pulse-width-modulation to accomplish a near-perfect sinewave output to
drive loads. These powerful synthesizers are very cheaply constructed and
very profitable.

The AC compressors synchronize to power line frequency (50 or 60 Hz), which
gives them a steady power output regardless of condensor pressure loading
which would drive a DC motor crazy trying to maintain counter EMF.

It makes little difference in efficiency running a switching inverter
outside......or building one inside for another $1500 to sell at the boat
store. The price difference is phenomenal!


I've got one. At least it says so on the can, Been tucked down under
the cockpit floor for ten years or more.

Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)