From: John De Armond
Newsgroups: alt.rv,rec.outdoors.rv-travel
Subject: Re: refrigerators while traveling (non-absorption)
Message-ID: <dgppgv8hafdea94mkkd82pau70obn9me50@4ax.com>
Date: Thu, 10 Jul 2003 00:30:28 -0400

I faced the same problem in my rig.  I originally intended to get the
absorption rig rebuilt and use the small under-counter 'fridge I bought at
Sam's Club only until then.  Having used the 'fridge for a couple of months
now I'm about to decide not to rebuild the old one.

what I did was place the fridge in the old opening and then frame around it
with thin plywood and trim.  Painted, this looks factory.  I sat the 'fridge
on the base plate of the old unit.  I then took some aluminum angle iron,
applied some 3M VHB (very high bond) structural tape (available in small
pieces at Ace, etc) to it and stuck it down on the top of the fridge so that
the other side of the angle pressed against the framing.  This is on the
inside of the cavity so that the angle doesn't show.  After the adhesive
cured, I used some round head self-drilling screws to fasten the angle to the
trim.  The result is a very secure mount that looks original.  The fridge I
got at Sam's has a key lock on the door which serves to lock the door shut
while underway.  Under the influence of the safety nazis, they made the key
spring-loaded so that the key could not be left in the lock.  I solved that
problem by drilling the spring capsule and then epoxying the key in the lock.

On the power side I have a 400 watt inverter connected to the fridge through a
transfer relay.  This is a simple 15 amp, DPDT 120 volt coil relay that
selects power for the refrigerator from either the inverter or the shore
power, depending on which one is available.  The coil is connected to the
shore power side so that shore power overrides.  That is, if the inverter and
the shore power are both available, the fridge gets shore power.

The inverter draws about 8 amps from the battery when refrigerating a hot
cabinet and with an outside temperature of about 75 deg.  Somewhat less once
the cabinet is cold.  The draw will go up some in hotter weather.  You can
figure what kind of battery life you'd get from that.  I have about 250 ah
onboard so I could run about 30 hours, given no other loads.  The draw is
insignificant to the engine alternator.

I mostly travel instead of camp so this is perfectly acceptable performance
and battery life.

The hot weather performance is superb, much better IMHO than an absorption
unit.  I've been datalogging the cabinet temperature during this recent hot
spell.  I have the 'stat set to 32 deg.  It has not risen more than a degree
above that even with the thermometer hitting 98 today.  I know from data logs
of the old unit that it would start losing control of the temperature at about
95 outside.

I used that $29 Vector 400 watt inverter from Sam's Club.  Unloaded, it draws
only a few ma from the 12 volt source so there's no need to turn it off.

If you choose another refrigerator other than the GE unit Sam's currently
sells, you'll need to investigate some.  Mfrs love to put little heaters in
the door gaskets, the butter compartment and a few other places to cut down
condensation, keep the butter soft, etc.  These heaters can draw almost as
much power as the compressor and they run all the time.

It's hard to tell by looking.  The reliable indication is how much current the
refrigerator draws with the compressor OFF.  Any load with the door shut and
the compressor off is heater load.  I took a clamp-on ammeter to Sam's, got
one of the employees to help me heft the fridge down and plugged it in.  I
then clamped the power lead in the back of the unit and looked at the draw.
The cabinet has to be cool enough that the thermostat turns the compressor
off.  Usually if you turn the control to "off" it also kills the heaters.  It
was cool enough in Sam's that I could simply turn the 'stat to minimum
cooling.

Another, perhaps easier method is to get a Kill-a-watt from Rat Shack or
equiv.  This is a plug-in device that measures volts, amps, watts, KVARS,
power factor, frequency and KWH among other things.  About $30.  Just plug it
in, plug the fridge into it and read the amps.  When you're not using it to
check out the 'fridge, leave it plugged in inside your RV to watch the power
quality.  Does more stuff than the Good Governor that everyone likes but at a
quarter of the price.

Oh yeah, you'd be wasting your money on a Danfoss setup.  Those were
kewl/necessary before the $30 inverters became as common as flies.  Nowadays,
a conventional line-operated 'fridge and a $30 inverter will do the same job
at about the same efficiency.  Plus, if the inverter craps out, toss it and
buy another.  I dare you to ask what the motor driver costs for a Danfoss....
Be sitting down and have your heart pills handy :-)

How long will the 'fridge last?  Who knows?  For just a bit more than $150, if
I get 2-3 years out of it I'll be more than happy.  Anything more is icing on
the cake.

John

On Tue, 01 Jul 2003 19:40:03 GMT, "Kevin" <k@biggreenball.com> wrote:

>I've been searching the web and newsgroups on absorption vs non-absorption
>type refrigerators for us in motorhomes.  My 1982 Norcold 3-way died
>recently, so I'm looking to replace it.  I've been looking at Danfoss
>compressor-based fridges such as the Novakool RFU8000.  Lots of folks say
>these do just fine in an RV, but my local repair shop says otherwise.
>
>My question is: how well do the compressor fridges hold up under constant
>travel?  I will be driving the RV every day while traveling around the
>country.  I have a generator and anticipate having electric hookups, so
>power shouldn't be a huge problem.  My concern is how well the compressor
>and seals and such hold up to constant jostling.  I've also looked at the
>Norcold DE-461, which is actually the one my repair shop cautioned against
>traveling with.  Is it any different from the Novakool?

From: John De Armond
Newsgroups: alt.rv,rec.outdoors.rv-travel
Subject: Re: refrigerators while traveling (non-absorption)
Message-ID: <nr1ugv82g5kd3kr4j0e8a946u1fcn3sdrc@4ax.com>
Date: Fri, 11 Jul 2003 14:54:30 -0400

On Fri, 11 Jul 2003 05:47:46 GMT, "GM" <nothing@nothing.com> wrote:

>Are you concerned about enclosing it in a cabinet?

No.  The back side is still vented to the outside via the same vents that
vented the gas unit.

>Most of those fridges are
>labeled as non-encloseable. Supposedly the heat can build up and they didn't
>thermally design the cabinet for venting out the front.

This is true.  The condenser is embedded in the skin.  In my installation
there is plenty of free air space around the skin.

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: refrigerators while traveling (non-absorption) - A followup
Message-ID: <rc1civ0lfjkkkjp71771puh9b71g5arqq9@4ax.com>
Date: Tue, 29 Jul 2003 01:38:35 -0400

This last weekend I conducted an impromptu test of my inverter/Sam's Club/GE
dorm refrigerator that I installed in my RV to replace the absorption unit.  I
ran the unit on battery power all weekend and logged the E-meter readings.
This is a good baseline test, as there were no door openings.

Outside ambient was in the mid 90s, 93-96.  Very high, almost saturated
humidity.  70s at night with high humidity.  In the shade so no direct
sunlight.  The setup used 90 amp-hours a day.  Average current - about 11
amps, varying from about 9 amps at night to 12+ during the heat of the day.
The best part of all - the cabinet temperature held to exactly the 33 deg
setpoint, something the absorption 'fridge would not do in weather like that.

This test was with my central 1000 watt vector inverter powering only the
refrigerator.  I will next test with the 400 watt inverter to see if there is
a significant difference.  I will also have a duty cycle data logger hooked up
to monitor how much the compressor runs.  I also plan to monitor the outside
temperature of the box and to see if a fan will help anything.  This
refrigerator is the type that has the condenser coils embedded under the skin
rather than a stand-alone coil in the rear.

This answered two central questions.  first, I now know for sure that I can
get a long weekend out of a single charge of my battery.  Two, the cooling and
draft in the refrigerator compartment is adequate without any modifications.
My rig uses the standard side intake, roof exhaust ventilation system for the
refrigerator compartment.

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: First inverter weekend
Date: Tue, 11 Nov 2003 15:55:43 -0500
Message-ID: <0bf2rv8s8v84vc43cohvk51bv79vg61l4u@4ax.com>

On Tue, 11 Nov 2003 16:13:43 GMT, "Peter Crowl" <pcrowl@earthlink.net> wrote:

>John
>What refrigerator are you using? Your results are very interesting as I'd
>like to go electric as well.
>Peter

Pretty much this one from Sam's:

http://tinyurl.com/ul0g

It's a GE compact (4 cu ft) refrigerator.  The one I have is white and has
somewhat different shelving.

The nameplate says that it draws FLA 1.3 and LRA 6 amps.  That's worst case.
When mine starts in 70 degree air it draws about 120 watts.  This decreases
quickly to about 90 watts.  In 50 deg air it drops to 60 watts.

One would think this reefer would work well on a 400 watt inverter.
Unfortunately it didn't, at least not on the Vector that Sam's sells.  Appears
to be the very low power factor during starting (<0.5)  Apparently that
inverter can't handle the very highly inductive load.  It doesn't trip; the
compressor simply doesn't start.  It would start with the engine running and
almost 14 volts available but it would NOT start on battery voltage.

The 1000 watt inverter doesn't even blip.  With no load on the inverter and
including the various detectors and clocks, the total battery draw is right at
1 amp.  With the refrigerator on the draw is in the range of 11 amps.

I'm going to experiment this week with some power factor correction to see if
I can get the current draw any lower.  I'd like to dedicate a 400 watt
inverter to the refrigerator alone.

I have the thermostat adjusted to keep the box at 33 deg.  Whatever space in
the freezer that isn't filled with food is filled with flexible blue ice bags.
Think of this as phase change cold storage.  With the power off the box stays
at between 33 and 35 degrees for about a day before it very slowly starts
rising.  I would guess that it will be good for 2 days.

This is the second part that I like about the electric 'fridge.  Unlike an
absorption or thermoelectric refrigerator, this one has the cold spaces
completely enclosed in insulation except for the small hole where the
refrigerant lines enter.  If I get in a situation where there is no power, I
can go for a day or two and not lose the contents.

I can understand why absorption refrigerators were used in the past before
inverters got so cheap and efficient but now I don't think I'd ever go back.

I'd love to get my rig to where it used only one form of fuel - gasoline.  If
I can convert over to a gasoline fired furnace I'll be mostly there.  I have
some induction ranges that will take care of most of my cooking needs.
There's still the oven and maybe I'll end up with a small portable propane
tank just for the oven.  I could live with that.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: First inverter weekend
Date: Wed, 12 Nov 2003 00:54:50 -0500
Message-ID: <p8i3rvkl7nutte0876loj1luhbep3gi57n@4ax.com>

On Wed, 12 Nov 2003 05:32:04 GMT, "Peter Crowl" <pcrowl@earthlink.net> wrote:

>Thanks Will and John...Hmmm - didn't realize that the small electric
>refrigerators were that efficient!

I don't know if they all are but this compact GE that Sam's sells definitely
is.  One thing I forgot to mention in the previous post.  it comes with a door
lock, designed to keep kids out, I guess, that works great to secure the door
while underway.  Only thing I don't like is the key is spring-loaded and
ejects when released.  I'm going to poke around and see if I can destroy that
spring without disassembling the door.  Or maybe just superglue the key in
place.

>
>John - During construction of our house addition we lived for almost a year
>using just a Sharp Convection  /  Microwave oven. Even made Thanksgiving
>dinner with it. 900 watts and extremely versatile. It's what I'd like to go
>to in the MH.
>See some here--   http://tinyurl.com/unm5

I thought about that.  I have a couple of those in the restaurant.  But to
cook the dishes like a rib roast that require hours of roasting would require
either shore power or running the generator.  My goal is to not have to run
the genny more than about an hour a day to recharge the batteries when I'm dry
camping.  To achieve that I'm pretty much stuck with a combustion appliance.

John K. dropped me a note and pointed me here:

http://www.wallas.com/index_eng.php

to a diesel fueled stove and oven.  Very interesting.  I'd still be stuck with
dual fuels, as my rig is gas powered, though I could fill up both fuels at the
gas pump, much better than dealing with propane.  I really want to get to the
single fuel configuration, though.  Maybe some company somewhere makes a
gasoline fired stove similar to the Wallas.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: First inverter weekend
Date: Wed, 12 Nov 2003 12:43:04 -0500
Message-ID: <rur4rvs9uea54595u1pb2nur6qb1a2pf93@4ax.com>

On Wed, 12 Nov 2003 07:50:50 GMT, Paul <momi.remove.@dowco.com> wrote:

>> The Corvair used an auxiliary gasoline heater on some models in the
>> 60's, if I recall correctly.  You may be able to find one in a
>> junkyard and adapt it.
>>
>>           ............gary
>
>So did theVolkswagen, but I doubt that either would be adequate to heat a motor
>home.

I have/had a volkswagen heater.  It put out a bunch of heat, enough to heat
the microbus.  And my racing van, back in the good ole days.  But.  It was
cantankerous.  It belched and sooted and roared on occasion.  Most of the
problem was in the points-type ignition system attached to the motor shaft and
the mechanical fuel pump.  That could be fixed, of course, but the odds of
finding a 40 year old combustion chamber in good condition are kinda poor.

I also had a post-korea vintage deuce and a half cargo area heater.  It too
burned gasoline and made enough heat to heat a small house.  But it required
24 volts and was the size of a roof-top AC unit.  I used it with two
motorcycle batteries to heat the tent we set up in the pits during a race.
Very nice.

Strangely enough, I'm not in the mood to do much hacking on this project.  I
want to find a unit that is designed for RV or large truck use and just
install it.  Low priority project so I'm not in any hurry.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Dometic fridge worth repair
Date: Fri, 28 May 2004 00:25:17 -0400
Message-ID: <atedb095s5987p69behchkm25gh8ick5uc@4ax.com>

On 27 May 2004 11:46:14 -0700, dmartin@newarts.com (dave martin) wrote:

>Repair or replace the absorption type fridge only if you do much dry
>camping. If you are almost always plugged in a regular compressor type
>refrigerator and inverter will cost a lot less and do a much better
>job for you.
>
>The inverter is to keep it running while you are driving, etc.

This is the route I went when my absorption unit went Tango Uniform.  I
installed an "office size" refrigerator in the hole vacated by the old unit.
I installed a 1kw inverter to run it and the microwave.  The power draw from
the refrigerator (about 80 watts if I recall) is so low that I can go for days
dry camping without recharging my 220 ah battery bank.  The 'fridge only runs
about 50% duty cycle in moderate weather (70's and 80's) so the actual energy
draw is much lower than the 80 watts would indicate.

The advantages are many:

* cheap - mine was about $150 from Sam's.
* quick cold - from ambient to 40 deg in a couple of hours.  No need to turn
on the night before.
* Totally insensitive to level, within any tilt the RV will stay upright :-)
* Mostly unaffected by high ambient.  Mine kept a nice 35 deg refrigerator
temperature in the 95 deg weather we had last weekend.
* The freezer is a real freezer, going below zero without any problems what so
ever.  Hard ice cream is NICE!
* No electronic boards to go bad and no computer to crash.
* No open flame to worry about while refueling (if you're the type to worry
about such things.)
* The cabinet layout is much more convenient for ordinary size containers than
the RV friges I've experienced.

I leave mine on the inverter all the time.  When on shore or generator power
the converter supplies the 12 volts necessary to run the inverter.  Somewhat
inefficient but I don't care - the convenience is worth it.

I originally installed the electric unit to "get by" until I could order a
replacement absorption unit.  Once I experienced the benefits of the electric
unit I forgot about another absorption unit.

To answer the obvious question of why I used such a large inverter, the answer
is reliability.  A 400 watt inverter would not reliably start the compressor.
It would most of the time but occasionally it would trip on overload in hot
weather.  That is, of course, unacceptable when the RV is left alone for a few
days.  A 500 watt one might do the trick and Sam's has one for $29 now but I
decided to go ahead and get the 1kw unit.  Only a little more money.  It is
stone cold reliable on the 'fridge and as a benefit it can run the microwave
too.  I really like being able to nuke leftovers or a TV dinner without having
to crank the genny.

I dry camped last weekend and got some VERY puzzled looks from neighbors as I
cooked french fries in my Frydaddy on my picnic table :-)  They couldn't
figure out how I was doing that, as there was no generator noise.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Dometic fridge worth repair
Date: Fri, 28 May 2004 00:29:22 -0400
Message-ID: <mrfdb0tjong1o4jsu53rbdifg6qtg51ejq@4ax.com>

On 27 May 2004 19:36:26 GMT, sorobon@aol.com (SOROBON) wrote:

>>and if it is a Dometic, Get a Norcold.
>
>I got to talk to lots of full timers this winter and we could not tell any
>difference between Dometic and Norcold all seemed to have early failures.  Some
>people had old manual models that had been working for 20 years.  The amout of
>use did not seem to be a significant factor and the newer models seemed to last
>5 to 10 years before they died. It seemed like many failures were caused from
>corrosion from the outside.  I wonder if units that stay in the SW where its
>dry last longer than in the SE or at the coast.
>Sorobon

My manual one failed last year at 20 years of age.  I ran down the leak and
found it under the insulation on the generator tube.  there was heavy rust
scale under the insulation and a small pinhole finally rusted through.

I suspect that this rust is caused by moisture collecting under the insulation
when the unit is off.  The previous owner used this rig very little and kept
it stored in a closed-in barn he built just for the rig.  I suspect that most
if not all the rust damage occurred then.  I always left the 'fridge on except
for defrosting.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: mini refrig in van
Date: Sun, 20 Feb 2005 08:52:41 -0500
Message-ID: <2j4h11h3njdnc75rf4roj2269qh4ued4m1@4ax.com>

On Sat, 19 Feb 2005 20:17:17 -0800, "Peter Pan"
<Marcs1102NOSPAM@HotmailNOSPAM.com> wrote:

>Eddie wrote:
>> I have just purchased a used V-10 Club Wagon and plan to use it to get
>> to campground.  In the past I've been using a cooler.  Now would like
>> to know if I can use a mini elec refrig plugged in using a converter.
>> The refrig is available at Home Depot.  The people there do not know
>> if it's possible.  I got this specs: 115V - 60Hz.  It's a Magic Chef,
>> 1.7 cu. ft.  The converter is 350 watt continuous, 800 peak.
>> Will it work?
>> Eddie

It'll work fine.  Just make sure you have a solid, low resistance (heavy
cables) connection to the battery.  That inverter will be on the edge to
supply the peak starting current.  It will trip if there is much voltage
drop in the supply wiring.

I removed the absorption refrigerator from my rig when it failed.  I
replaced it with a waist-high dorm room fridge from Sam's and a 400 watt
inverter.  That was 2 years ago.  I like it well enough that it has become
permanent.  The shelves do NOT rattle and the door has yet to fall open,
something I cannot say for the old RV refrigerator.  If I'm ever in fear
of the door falling open, I simply turn the door lock conveniently
supplied by GE.

If you plan on running the refrigerator when you're stopped, please
install a second deep discharge battery and an isolator.  Your cranking
battery will thank you.  The 120 to 12 volt current ratio is about 10:1 so
if your fridge draws an amp, the inverter will draw 12 from the battery.
You can see that this would draw down a cranking battery in just a few
hours.

As for thermoelectric coolers, I think everyone should experience one at
least once so that he'll appreciate a good conventional refrigerator.  The
TE pile will achieve a COP of a little less than 1 under good conditions.
That is, about 1 watt consumed for each watt pumped.  That l'il fridge
will do better than 2 under similar conditions.  The TE module is lucky to
maintain a 40 degree delta T.  That means that when it is 100 deg in your
parked car, the inside where all that potential food posioning is lurking
ain't gonna be below 40 degrees where it is safe.

The little TE coolers are fine for sitting on a motel counter in an air
conditioned room.  I used one for years when I road warriored to keep soft
drinks, cold cuts and the like safely cooled.  I very quickly learned that
the same does not hold true when the cooler is placed in the car.  For
traveling I used ice.

I now have one of these:

http://www.advrv.com/engel/engel_45.htm

It will hold things at -10 deg F even in the hottest weather.

A smaller one suitable for car use might be one of these

http://www.advrv.com/engel/engel_16.htm
http://www.advrv.com/engel/engel_15.htm

These are, of course, more expensive than the TE units but here again, you
get what you pay for. The advantages these have over the dorm room fridge
include a lot less power draw (mine draws about 3 amps), top opening and
handles to carry them by.

John

>
>Look at the thermoelectric coolers instead (like the igloo
>http://www.igloocoolers.com/). Can plug directly into the cig lighter, and
>when in a place with reg AC, has a converter that plugs in and gives 12 VDC
>to run it. Truckers use em, tailgators, college students in dorms,
>beachgoers, etc. I have one I use in the RV, toad, beach, camping, etc. and
>it's great when driving/staying at friends houses/motels etc.
>
>While the smaller ones are fine if you are stopped (like the mini fridge
>above), they are rather susceptible to motion, and the shelves/insides
>aren't made for movement (shelves aren't meant for travel and things moving
>around, the door isn't made for travel either, tends to open and things fall
>out).
>
>For info on that (Magic Chef only has fridges down to 3.8 Cu Ft, and Home
>Depot doesn't sell them anyway)
>
>But for an approximation of other small cube fridges about that size at
>http://www.compactappliance.com (find a model and look at the Energy Guide)
>Energy requirements: 110 Volts/ 60 Hz, 1.3 Amps  (about 143 watts)
>

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: mini refrig in van
Date: Sun, 20 Feb 2005 22:37:52 -0500
Message-ID: <phki119jhjt2cubon87cdlbh067gr79k0u@4ax.com>

On Sun, 20 Feb 2005 08:34:44 -0800, "Ben Hogland" <benhogland@hotmail.com>
wrote:

>"Neon John" <johngdDONTYOUDARE@bellsouth.net> wrote in message
>news:2j4h11h3njdnc75rf4roj2269qh4ued4m1@4ax.com...
>> I now have one of these:
>>
>> http://www.advrv.com/engel/engel_45.htm
>>
>> It will hold things at -10 deg F even in the hottest weather.
>>
>> A smaller one suitable for car use might be one of these
>>
>> http://www.advrv.com/engel/engel_16.htm
>> http://www.advrv.com/engel/engel_15.htm
>>
>> These are, of course, more expensive than the TE units but here again,
>> you
>> get what you pay for. The advantages these have over the dorm room
>> fridge
>> include a lot less power draw (mine draws about 3 amps), top opening
>> and
>> handles to carry them by.
>
>I've never seen these before. Those are nice frig/freezers. Wonder how
>they keep the current down so low. These might even be suitable for long
>term boondocking if one had a generator to charge a bit every two days
>or so. At 700 bucks, they are still cheaper than an absorption frig.
>Obviously more reliable than an absorption refrig and no requirement of
>being level to operate.

You probably have seen this unit, as Norcold private labels it.  I see
them on display at CW.  Here's the Norcold version at CW:

http://www.campingworld.com/browse/products/index.cfm?prodID=1247&src=SRQZ

I figured I'd save money not buying the brand name plus the guy at
Advanced RV has always done me right.

I was curious about the power consumption too so (of course) I took mine
apart.  It contains a tiny 3 phase hermetic compressor driven by a 12 volt
powered inverter.  It might even be a permanent magnet brushless DC motor,
I couldn't really tell from the outside.  When the unit is plugged into
120 volts, a switchmode power 12 volt power supply runs the thing.  One
can leave both the 12 volt and the 120 volt cords plugged in.  The unit
will run from whichever has the higher voltage.

13.8 volts at 3 amps = 41 watts is actually a decent amount of power.
That is about 1/18th horsepower.  I've seen dorm room fridges with
compressors in that power range.  I have a dessert display case that uses
a 1/16th hp compressor - I know as I just had to replace it.

Other factors include the good insulation and the still air space around
the food basket.  I use mine mostly as a deep freezer set at -10.  At that
setting it runs perhaps 75% of the time.  That's impressive.

One thing that makes me think that the motor might be a permanent magnet
rotor type is the almost complete absence of startup inrush current.  When
the controller calls for cool (the "thermostat" is really just a pot), the
compressor just sorta starts turning.  The current starts out somewhat
above normal run current during the initial pull-down stage but there is
none of this 5X or more startup surge like on regular compressors.

This unit illustrates how obsolete absorption rigs really are.  Given the
efficiency of this electric compressor, someone could make an upright
tri-fuel refrigerator that would run on 120, 12 and propane or diesel
using the thermoelectric generator I described earlier.  Stone cold
reliable, no hot weather problems, no level problems and much cheaper to
build.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: mini refrig in van
Date: Sun, 20 Feb 2005 22:51:10 -0500
Message-ID: <80mi11dc914sc9on01hr0uj3u3t8gj03sv@4ax.com>

On Sun, 20 Feb 2005 22:23:03 GMT, Eddie <hawaii-50@sbcglobal.net> wrote:


>Sorry, I did mean inverter.
>The door closing/opening seems to be an important equation in this
>whole process.  When and if I do decide to purchase the mini refrig I
>certainly won't worry about that door opening during flight.  I will
>have enough stuff in the same area to make sure that door stays shut.
>The trip we take to the private ranch is only two hours.  We will use
>the refrig to keep the food cold until we arrive, then transfer all
>food to trailer refrig.

>My concern now is about the drain on the main battery.  I don't want
>to go through the trouble like making a hole to access an extra
>battery as Tom says.  Nor buy a larger inverter.  And I am connecting
>to the battery via 12v plug (cig. lighter).  I suppose for long
>distance use I would reconsider this set-up.  I should have explained
>that it's for very short distance and time.  I'm thinking perhaps it
>would be wise to run the refrig off house power for an hour or so to
>get it cold, then just before take-off, plug to 12v.
>Thanks for your input

As others have said, an ice box would probably do you OK for this
application.  I still like the refrigerator idea because it gives you
margin of error.  IN case you decide on a detour or have a breakdown or
something.

As long as the engine is running you don't have to be concerned by time or
distance.  Your vehicle's electrical system can more than handle that
load.

You might consider what I do when I take my portable refrigerator on a
trip in my car or truck.  I bought a 100ah marine AGM battery.  This type
of battery is vent-free and can be oriented in any position.  Think of it
as a lump that stores power.  With my portable reefer drawing 3 amps, I
can theoretically run it 100/3= 33 hours.  So as not to drain the battery
completely I'd limit that to 24. And since the unit doesn't run all the
time, I can in practice, get almost 2 days out of the battery.

I have a little cable that I made up that has a male cigarette lighter
plug, a female plug and a couple of gator clips.  I sit the reefer and the
battery in the trunk or truck bed.  The reefer plugs into the female cig
lighter plug.  The clips go to the battery and the male plug plugs into a
cig lighter plug I installed in the truck bed and in the car trunk.  If
I'm in someone else's vehicle, the cord is long enough to reach up front
to plug in the normal cig lighter plug.

When I stop, I simply pull the plug from the cig lighter.  This is a
manual battery isolator as it were.  When I come back, I plug it back in
and let the vehicle's system charge the battery.  The vehicle's system
will never fully charge the AGM battery so I charge it at home when I
remove it from the vehicle.

I actually use this setup a good bit.  My mom likes to go over to the
Tullahoma PX and buy up supplies.  That's about a 2 hour drive and often
as not we'll end up in Nashville.  No more worrying about all that meat
and stuff getting hot.

The AGM was about $130 as I recall.  Add $10 for the connectors and wire
and you're set.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Need Dometic "guts"
Date: Thu, 23 Mar 2006 04:11:04 -0500
Message-ID: <p8n4225b1thdjengin21q2to0t0ni4vpd1@4ax.com>

On Wed, 22 Mar 2006 23:19:14 GMT, "JerryD\(upstateNY\)"
<jerry@righthere.com> wrote:

>>>I have a dedicated 400 watt inverter to run the 'fridge on 12 volts.
>>>It runs all the time, drawing about 8 amps when the compressor is on.
>>>When I'm underway it runs from alternator power.  When I'm parked it
>>>runs on shore power from the converter. When I'm dry-camping it runs
>>>from the batteries.<<
>
>John,
>I need a fridge and I can buy a 120 volt one at Home Depot that will fit
>right in for $299.00.
>Can you explain how you wired it, in less that 1000 words.  <g>
>Do you have to manually switch it from your engine battery (while you are
>driving) to your RV supply batteries when you stop ?

1000 words or less?  Gee I don't know.....  That's like sending me to
the hardware store with only $10 to spend :-)

The first thing to do is evaluate the 'fridge.  Since I converted my
rig I've been paying attention to small 'fridges.  It seems that I got
lucky.  Mine only pulls about 50 watts with a high power factor.  I
recently bought a Sears 'fridge of about the same physical format for
my restaurant that draws over 100 watts at a PF of about 0.4.  That is
horrible!  Inverters vary in their responses to low PF loads.  Some
handle it OK, some draw excessive 12 volt current and dissipate extra
heat and some just flat won't work.  It's best to avoid the situation
if possible.

I highly suggest you get a Kill-a-Watt and check out the candidate
'fridge.  You'll find a thousand uses for the Kill-a-Watt once you
have it.  Not the least of which is leaving it plugged in inside your
rig to monitor shore and generator power.  Like a Good Governor, only
cheaper and more functional.

I'm finding that the nameplate ratings aren't very accurate.  I
consider them to be more of a "not to exceed" value, particularly on
amps.  You need to know the actual amps the compressor draws.  Using
the 10:1 rule for a 12/120 volt inverter, whatever that amperage is,
the 12 volt draw will be 10X.  To keep the 12 volt draw under 6 or 8
amps, the 'fridge needs to draw no more than 0.6 to 0.8 amps.

OK, now that we have that out of the way....

How you connect the inverter will depend on the kind of converter you
have.  If yours is a simple converter that is connected in parallel
with the battery and simultaneously charges the battery and powers the
house loads, all you need to do is connect the inverter to the house
battery.  Whatever you have that connects the house battery to the
engine electrical system (diode isolator or relay isolator) will take
care routing power from the engine when it's running.

If you have a Magnetek 6300 or a 7xxx series, the situation is a
little more complex.  This type of converter has an internal relay.
When shore power isn't available, house loads are supplied through the
relay's NC contact from the house battery.  When there is shore power
available, the relay is energized.

In the 6300 there are two classes of outputs - raw and filtered.  Raw
is 60hz right off the rectifier and filtered has a filter cap in the
circuit.  Raw is for lighting loads that ripple doesn't bother.
filtered is for 12 volt radios and other items where ripple is bad.
Both raw and filtered are fed from the battery when there isn't any
shore or generator power.  When there is, one set of contacts switches
the raw output to the rectifier and another contact switches the
filtered output to the filtered DC output.  Yet another contact
switches in a low current charging circuit to the battery.  I'm not
familiar enough with the 7xxx series (switchmode power supply) to say
but I bet that it only has one type of output (filtered) since the
SMPS doesn't have any ripple.  You'd have to check your manual.

You'll want to run the inverter from a filtered output.  The 6300 has
several fused outputs on both the filtered and raw outputs.  You
should have a vacant output available.  If not, piggyback on a low
current circuit.

Fuse the circuit for 30 amps.  This will adequately handle the inrush
demand when the compressor is starting. I suggest putting the inverter
close to the converter to keep the 12 volt wiring short.  Your fridge
should have a dedicated 120 volt circuit from the breaker panel.  Just
lift that circuit from the breaker, install a plug on the wire and
plug it into the inverter.

But that's not all.

The wiring from the battery to the battery terminal on the converter
has to be heavy enough to handle all the house loads PLUS the inverter
when you're dry camping.  Of the RVs I've seen up close, none have had
heavy enough wire.  My mom's MH, for instance, has #8 wire run from
the front battery box right behind the driver's seat, all the way to
the back, across the back and half way up the passenger side to the
converter.  That is not nearly large enough to supply the house needs
and the inverter AND not drop enough voltage to cause the inverter to
trip on under-voltage.

If this is the case with your rig, you'll need to run heavier wire
between the battery and converter.  Since it's cheap, very flexible,
readily available and very abrasion and chemical-resistant, I'd go
with say, #2 welding cable.  This is fairly light gauge cable as
welding cable goes.  You can get it anywhere from Tractor supply to
Home Depot to your local welding store.

Once you get that done, you're set.  When on shore or generator power
the inverter will run from the converter's filtered output.  When dry
camping the inverter will run on the house battery through the
converter's battery wiring.  When underway, the inverter will run on
the alternator, through the house/vehicle isolation device and through
the converter's battery wiring.

Executive summary: You'll need to connect the inverter to the
converter's filtered output and you'll need to check/upgrade the
wiring between the battery and the converter.

If you have some other architecture, if you can describe it to me then
I can make a recommendation.

My rig is a little different, for example.  It came with a dumb
ferroresonant converter that was hooked directly to the battery.  It
output 13.8 volts which sorta charges the battery and runs the house
loads.  I installed an Intellipower/Charge Wizard to handle the
battery.  The max voltage during the absorption phase is high enough
to shorten light bulb life and will reliably trip an inverter on
over-voltage.  So I wired up a transfer relay.  The Intellipower is
connected to the battery at all times.  When shore or generator power
is available, the relay transfers the house loads from the battery to
the ferroresonant converter.  The battery is now isolated from the
house and can charge at whatever voltage is required.

I also installed one of those big ole 1 farad capacitors that the
boom-boom stereo kids use. This cap holds up the house voltage while
the relay switches.  That keeps the lights from blinking, the clocks
from resetting, the stereo from thumping and so on.  It also supplies
plenty of surge current to the refrigerator compressor so that the
lights don't dim when it starts.  I could have arranged a
make-before-break relay but the cap from a pawn shop was cheaper :-)

I think I exceeded my word budget just a little....

John

From: John De Armond
Newsgroups: alt.energy.homepower
Subject: Re: best portable power pack?
Date: Wed, 28 Jun 2006 16:06:27 -0400
Message-ID: <6hl5a2pvplu4qcqdiu3u5q6bjsr8gocir9@4ax.com>

On 28 Jun 2006 10:55:18 -0700, "Tony Wesley" <tonywesley@gmail.com>
wrote:

>
>Neon John wrote:
>> A small dorm room 'fridge that draws 50 watts or so is less than $100
>> from Wallyworld, less than $20 typically from the pawn shop.  You can
>> run it on any of the tiny inverters that can be had for $20 or so.
>
>Can you?  I've asked about this before and gotten mixed responses about
>the tiny fridge starting on one of those little inverters.

Yes you can.  If you do your homework first.  I've written about this
fairly extensively over in rec.outdoors.rv-travel so you might want to
google over there.  I would have been jgd at johngsbbq.com or before
that johngd at bellsouth.net, but always neon john.

In a nutshell, it depends on all three components - the 'fridge, the
inverter and the power supply.  In my experience from troubleshooting
other people's installations, the main reason that the fridge won't
start is inadequate wiring to the inverter.  The wire tables that most
of the inverter makers include in the manuals are marginal to garbage.
Yes, the wire size will work when the engine is running, the battery
is charged and the wire length is short.

When the battery is down on charge, the wire length is significant and
the 'fridge is one that is particularly inverter-unfriendly, it won't
work.  At all times during the starting cycle, the voltage AT THE
POINT OF SENSING inside the inverter has to be above the minimum
voltage cutoff or else the inverter will shut down.  I've
reverse-engineered a number of cheap ChiCom inverters of various
names.  During a particular period of manufacture, they all are the
same, plus or minus details.  It seems like someone somewhere
engineers a product and then all the cheap ChiCom manufacturers make
product to that plan.

Anyway, the voltage has to be adequate under the worst conditions.  To
that end, in my RV I've installed a homemade "power center" that
consists of little more than a couple of hunks of copper bus bar, one
for each pole, on insulated mounts, fed by fairly short lengths of 4-0
welding cable directly from the house battery.  Within a couple of
feet of this power center are my generator, my refrigerator inverter
(formerly 350 watt, now 500), my house inverter (2kw, Harbor Freight
el-cheapo) and my 60 amp progressive dynamics charger with the Charge
Wizard.  The refrigerator inverter is connected to the bus by about 2
feet of #4 wire.  I'd have probably used #2 had I had some on hand.
There is but a few dozen millivolts of drop from end to end with this
system, even with the inverter at full chat drawing nearly 200 amps.

The inverter must, of course be able to handle the surge.  Most all
can.  Of primary importance if the 'fridge is to be operated
unattended is that the inverter self-reset from faults such as
undervoltage, overvoltage, etc.  I lost a couple of 'fridges full of
food learning that lesson.  The charger bumps up against the
inverter's overvoltage trip at the end of the bulk stage.  With my
current inverter (a Power To Go 500 watt unit from Sam's Club), that's
no big deal.  It trips occasionally on over-voltage but immediately
resets when the voltage comes back down again.

My previous inverter was a Vector 350 watt unit.  It ran the 'fridge
just fine but it had to be power-cycled to reset a trip.  Rotten food
is the result.

I run a dedicated inverter for the 'fridge so that if something trips
the main inverter, the 'fridge keeps on running.

Inverter-friendly 'fridges.  This refers to both the inrush (a minor
problem in most cases) and power factor.  Inverters vary as to how
they handle low PF loads.  Some keep on truckin.  Some draw extra
battery power and dissipate the difference between real and imaginary
power output as heat in the electronics.  Others simply won't run. By
low PF, I mean below about 0.7.

The fridge in my RV was the first that I bought intending to run on an
inverter.  I got it at Sam's Club after looking at the nameplates.  It
draws about 80 watts peak and about 50 watts running.  I got lucky, in
that I didn't think to check the PF.  It is about 0.85 peak and about
0.75 running (induction motors drop PF as the load decreases.)  By
peak I mean the peak cooling load right after startup and not the
starting inrush.

I bought a very nice small Kenmore 'fridge at a pawn shop (still had
the stickers on it) intending to replace the Sam's unit.  This 'fridge
did not contain a freezer compartment which I don't need since I carry
a portable freezer also.  I got it home, plugged it in through my
Kill-a-Watt and observed a peak PF of 0.5, dropping to the low 0.4x
region running.  My inverter is the type that draws excessive current
and gets hot with low PF loads.

I have corrected the PF to almost unity running using a suitable run
capacitor across the line terminals but I haven't tried it on the
inverter yet.  The almost-square wave output is rich in harmonics
which I anticipate to force a change in capacitance.  Or maybe the
inverter won't like the instantaneous capacitive load and will refuse
to work.  I won't know until I test.

I've since built several of these setups in one form or another for
friends and net.acquaintances and I've learned to take along the
Kill-a-Watt and actually measure the candidate 'fridge.  I've learned
that there is no reliable outward indication of PF.  Some high priced
brand name 'fridges have PFs below 0.5 and some cheap-sh*t ChiCom junk
have PFs up in the high 80s.

If absolute efficiency and reliable operations under marginal
electrical conditions are important then there is another alternative.
Remove (or have removed) the stock compressor and install a Danfoss 12
volt unit.

The Danfoss looks and performs like any other hermetic compressor
except that the motor is a brushless DC motor.  The inverter to drive
it is built onto the compressor housing.  Apply 12 or 24 volts and yer
coolin'.

My portable freezer contains a Danfoss.  Overall system efficiency -
from battery to cold - is about a third better than my
inverter/'fridge setup even though the temperature differential with
the freezer is much larger.  The difference is readily apparent - the
Danfoss compressor operates at near room temperature while the
inverter-driven compressor is too hot to touch.

The Danfoss has a permanent magnet rotor with no electrical losses
while the regular induction motor has a squirrel-cage rotor that has
to have some loss to work.  The Danfoss stator laminations are
selected for the high frequency service while the regular fridge's
laminations suffer higher eddy current losses from the harmonic
content of the almost-square wave output of the inverter.  I think
that the Danfoss also runs faster which is generally more efficient.

The Danfoss is standard fare in marine environments such as sailboats
where the power budget is even tighter than on an RV.  I've been
giving serious thought to converting my 'fridge since with my current
battery bank I could get almost another day per charge.  OTOH, for the
~$400 the compressor costs, I could figure out someplace to add
batteries and fabricate mounts.

>I have a couple of those little inverters, Coleman, supposedly rated at
>400 watts.  I'd like to run a bar fridge off of that.

Only way to know is to try it.

>
>> That's a little more expensive than the Koolatron but vastly more
>> efficient.
>
>Once you figure in the cost of the battery, the dorm fridge setup might
>even be cheaper.

Probably.  And more importantly, the contents would actually stay
cold.  About the best a single stage Peltier can do is a 40 degree
differential.  In a 70 deg room, no problem.  In a car's interior in
the middle of summer at say, 110 deg, not so good.  70 deg food makes
Mr Salmonella quite happy :-)

John

From: John De Armond
Newsgroups: alt.energy.homepower
Subject: Re: best portable power pack?
Date: Wed, 28 Jun 2006 16:19:13 -0400
Message-ID: <tbo5a2lso9rtb02jee7hdpe0ulj6qfv651@4ax.com>

On Wed, 28 Jun 2006 14:33:39 -0400, "soundhaspriority"
<nowhere@nowhere.org> wrote:


>True, but in the jostle of the Jeep, the coils hanging off the back would
>likely be damaged. The Koolatron can be thrown around. But I do wish they
>made inexpensive chests with mechanical refrigeration. They are exorbitantly
>priced.
>

Few of the dorm fridges have coils on the back anymore.  Most now have
the condenser coil embedded in the cabinet, right under the skin.

have you looked at the $400 portable unit that Camping World sells?
About the same size and weight of a peltier cooler but with a
compressor.  I'd post a link but I'm on a very slow dial-up link right
now.  I'm sure you could find it cheaper than Camping World because
they're invariably the high price leader.  Look at
http://www.advrv.com  He carries a line of compressor-based portables
and invariably has the best prices.  I'm just a satisfied customer so
I can highly recommend him.

There may be a little sticker shock at $400 but by the time you rig up
something that will actually run that Koolatron for a day, you're
going to be in that price range.  And your food will still get hot.

When I go off-roading with friends, I take along my portable freezer
(look on that advanced RV site under "specials".)  If I'm not carrying
ice cream I just turn up the thermostat and use it as a refrigerator.
It'll maintain -10 deg F for ice cream and still not run 100% of the
time.  It'll hold 32 deg at maybe 20% duty cycle which means that a
100 ah battery will run it for at least a couple of days.  I have the
next-to-largest size and spent about $700 on it.  Money VERY well
spent, in my book.  I like to boondock for days at a time in my small
motorhome so the large version is necessary for me.  For day trips one
of the smaller units would work fine.

I don't have a Jeep of my own but I seem to get invited a lot because
of that portable freezer :-)  Sure is nice to have ice cream and
really cold drinks after an afternoon of winching people up a mud bank
:-)  And steaks for supper.

If I didn't have the compressor-based unit, I'd be using ice in one of
the super-insulated coolers.  That would be good for several days and
I'd know my food would stay cold.

John

From: John De Armond
Newsgroups: alt.energy.homepower
Subject: Re: best portable power pack?
Date: Wed, 28 Jun 2006 22:31:08 -0400
Message-ID: <afe6a2571l30veiff0pae6f84d8t1nvc3e@4ax.com>

On Wed, 28 Jun 2006 23:51:50 GMT, "JoeSP" <olegp@msn.com> wrote:

>
>"Sorobon" <Sorobon@AOL.com> wrote in message
>news:44a30b0d$0$23739$a8266bb1@reader.corenews.com...
>> Have I missed something here I thought the Koolatron is on all the time
>> and draws the same amount of power continually, unless you have installed
>> a thermostat?
>>>
>>> Refrigeration and storage batteries are not a good marriage.  You can
>>> store a lot more negative thermal energy pound for pound in ice than you
>>> could generate from a battery.  Wrap your Koolatron in another layer of
>>> insulation and you won't need to expend so much energy keeping it
>>> chilled.
>>>
>
>I suppose I forgot to mention unplugging it after it's done its work.

Then the peltier pile works in Seebeck mode and while driving the fan
and LED indicator, pumps heat back in just about as fast as it pumped
it out.  Even if one installs a switch at the pile to make sure it
sees an open circuit, the pile material is a fairly good heat
conductor and will conduct heat back in only a little slower.

There IS a reason why you never see a thermostat on a peltier cooler.

A peltier pile actually makes a pretty good generator.  I once made a
12 volt battery charger that consisted of a number of commercially
available piles arrayed around a thick copper tube that was heated by
a propane torch. The other sides of the piles were against a very
large heat sink cooled by a muffin fan.  The output is basically
limited by the delta-T across the junctions and THAT is limited by the
low temperature indium-based solder used to assemble the pile.  I
limited the hot side to 350 deg F and never had any problems.

John
>

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Engel portable fridge and Advanced RV sales
Date: Sat, 14 Oct 2006 15:00:07 -0400
Message-ID: <61c2j2578qdnbvgvhirh1109tdd27ju5g2@4ax.com>

I just called up the guy (racking my brain for his name) at Advanced
RV (http://www.advrv.com) and ordered a second Engel 45 portable
freezer for my truck.  In the process I had a nice long chat and
learned some things that might be of interest.

First off, he hasn't updated is website in awhile and the prices for
the freezers are considerably better than listed.  The 45 is $665 and
the 35 is $620, both with free shipping.  I didn't ask about anything
else.

This is the Cadillac of portable refrigerator/freezers.  It'll
maintain below zero temperature in even the hottest inside-vehicle
temperatures.  It draws about 3 amps max and doesn't run all the time.
Has a built-in converter so it runs on 12 or 120 volts.  It seems
expensive but once you've tried all the others and then this one, it's
worth it.  What I like, other than the refrigeration ability, is that
I can leave it in the truck over a 4 day weekend and not have my
batteries run down.

We got to talking about generators and trucking anti-idling laws.
Though not listed on his website, he's a Yamaha dealer.  He said that
he's selling bunches of the Yamaha boosted inverter generators and the
lightweight Carrier RV AC listed on the "specials" page to truckers.
He says that the battery boosted Yamaha kicks Honda's butt for
starting ACs (he sells or has sold both brands so no financial bias
there.)  Based on what I've seen, I agree.  The Yamaha is a superb
generator and somewhat cheaper than the equiv EU.  For a truck this
isn't as good as an APU but it's a bunch cheaper.

We chatted about a few other things but these are the highlights. I've
been doing business with this guy for years.  I've bought two
generators, two of these freezers and an RV AC from him and have been
superbly pleased.  One generator was DOA.  He sent me a new one even
before the old one arrived back at his place and he paid the shipping.
Can't ask for more than that.

I don't have any financial ties with this guy and don't even get a
discount for saying nice things about him :-)  I just like to pass
along info on the good guys.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: studio fridge in rv
Date: Sun, 15 Oct 2006 20:59:54 -0400
Message-ID: <rnl5j2lhdv8i1l5ogunbsbv4jal8nr4sih@4ax.com>

On Mon, 16 Oct 2006 08:40:12 +0900, "DH" <hornickd@hotmail.com> wrote:

>
>"> I have an office-type fridge and inverter in my rig too.  I installed
>> it when the absorption one went tango uniform.  Among the reasons:
>> more refrigeration capacity than an absorption unit, vastly better
>> performance in hot weather, much lighter, better organized shelving
>> (do any of the RV fridges actually ever USE 'em?), and last but not
>> least, cheaper.
>>
>> I've sketched out a plan to have one on top of the other on heavy-duty
>> slide rails so that one can be slid out to open the lid.  Top opening
>> (chest type) units are significantly more efficient than uprights if
>> opened very much for obvious reasons.  Plus in an RV, stuff doesn't
>> fall out when the door is opened like it does in an upright.
>>
>> John
>Exactly what I was telling my wife.  Uprights let all the cold air fall out
>when you are digging around for stuff while top loading doesn't.  There are
>a lot of small models around here in Japan that I should be able to use in a
>van with the correct power setup.  Thanks.

If you're serious about boondocking with an electric fridge/freezer
then I recommend spending the extra money for a Danfoss or clone
compressor.  That may very well cut in half the amount of battery
charging you have to do.  Like I mentioned before, the marine world
has this nailed, as people want to stay out on ocean-going sailboats
for weeks at a time with nothing other than solar or a small wind
turbine for power.  I can't point you to a website off the top of my
head but I've seen a number of top-loader fridges and freezers.

There's another option too.  Many of the marine refrigeration makers
offer "cold plates" for custom built refrigeration.  This consists of
a battery powered condensing unit and a plate-type evaporator.  You
build your custom heavily insulated box around the plate, then set
your food on top.

If you want to go cheap'n'dirty, you can convert a small chest freezer
into a refrigerator.  I've seen a number of projects on the net where
people living off-grid have converted chest freezers.   Usually all
that's involved is adding a suitable thermostat to control the
temperature 35-40 deg and something to deal with condensate.

If you're handy with tools you can buy a Danfoss compressor and
replace the 120vac (or is it 100 volts in japan?) unit.  If you don't
do refrigeration you could have a refrigeration tech do it.

One thing I really like about the Danfoss is the variable speed.  The
speed is set via a resistor in the thermostat lead.  One can arrange
high speed when quick cooldown is needed or when a large heat load is
put in the fridge (hot leftovers) and then run it slow for temperature
maintenance.  I need to poke around in my Engel and see if that
controller has the same capability.

Condensate is something you have to deal with.  When I use an Engel as
a refrigerator, the condensate puddles instead of freezing to the
walls.  I put a towel in the bottom.  The food goes in a lift-out
basket so periodically I just lift out the food, remove the soaked
towel and replace it with a new one.  I've found that to be better
than just letting the water collect where it will slosh up on the
food.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Question.....120 volt fridge
Date: Tue, 10 Jul 2007 03:31:13 -0400
Message-ID: <8tc693then1l49jc3v31nojkl61leiv3g7@4ax.com>

On Mon, 09 Jul 2007 20:56:17 -0400, Steve Wolf <newsgroup@w8iz.com> wrote:

>John -- I know it has been answered but please say again the typical
>power draw.  Also, there is no need for a special inverter, right?  Any
>old Sam's Club job will do?
>
>I replaced my three way in the last RV.  That sucked.
>
>Steve
>www.wolfswords.com under the motorhome link

60 to 80 watts.  Duty cycle varies with outside temperature but typically less than
50%.

Don't hold me to the duty cycle number.  I'm going from memory.  I posted the actual
numbers from my 'fridge awhile back when I measured it but I'm not sure of my memory.

Any old inverter will work.  I started out with a 350 watt Sam's special.  It worked
but would not reset itself if it tripped from under/over voltage.  It's now wired to
my 1500 Watt Power-to-go inverter (Sam's Club, $100 est) that DOES reset itself.

Since I've gotten the two Engels and seen the vastly superior power consumption of
the direct drive 12 volt compressor system and chest architecture, my mini-fridge is
coming out and the Engles are going in, mounted on heavy duty slides.  Again, I don't
recall the numbers well enough to quote but the amp draw is something like 3 amps
with an about 10% duty cycle when set to 32 deg.  Remarkable, actually.

About the only really important thing I can think of to look for in a mini-fridge,
other than good power factor, is an external condenser.  This is the type with the
coil on the back.  The other type, embedded under the skin, is inefficient and
precludes adding additional insulation around the cabinet.  I packed the spaces over
and to either side between the cabinet and the 'fridge with fiberglass insulation.  I
haven't made any measurements but since the outside of the fridge cabinet was
noticeably cold to the touch, the insulation has to help.

John

From: John De Armond
Newsgroups: alt.energy.homepower
Subject: Re: Basic Absorption Principles
Date: Thu, 06 Dec 2007 14:54:51 -0500
Message-ID: <uojgl3dl1jv42uhmmob26e8bjnj1fdsn5l@4ax.com>

On Thu, 6 Dec 2007 11:02:54 -0800, "Ulysses" <eatmyspam@spamola.com/> wrote:


>>
>> I have two of these:
>>
>> http://www.advrv.com/engel/engel_45.htm
>
>I've searched all over the place for various freezers and did not come
>across these.  I even bought two different electric (AC) freezers that were
>supposed to use very little power.  Both used about three times what they
>were rated at.  This sounds like it should work for me.  Thanks.  I still
>have my 440 Ah 12 volt battery bank that is not being used so that should do
>the trick.

I dug out my test data for a unit operated as a refrigerator:

11/17/06  Fri

0100  Engel refrigerator test.

Measured values:

Run time 3 days, 72 hours.
Temperature in fridge - 35.0

Watt-hours - 966.3
Watts peak - 51.7
Amps peak - 4.16
Amp-hours - 12.67
Voltage min - 8.74

instantaneous values

Off
Amps - 0.01
Volts - 12.00
Watts - 0.1

Running
Amps - 2.25
Volts - 11.53
Watts - 25.5

Computed values:

used per day:

amp-hours - 4.22
watt-hours - 322

Approx average duty cycle - 53%

During the test interval, the following items were placed in the fridge

12-pack of soda, room temperature
6 pieces of fried chicken, hot
1 meatball Sub, hot.
4 bottled sodas, room temperature

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

The data was recorded in my semi truck using a Watts Up meter.  This is the DC
version that all the RC model types have gone gaga over.  The power source was the
120 amp-hour AGM battery that I mentioned earlier.  I used it to power my accessories
so as not to impact the truck's batteries when parked.

The one designated as the freezer uses the bulk of the power, as one would suspect. 0
to -10 is pushing the limits for an R-134a system so it isn't surprising that it
likes a bit more electricity.

This same unit is private labeled for one of the big RV reefer makers - Dometic, I
think - at about half again as much money.

It uses a patented "swing" compressor.  This compressor uses a piston operating at
its mechanically resonant frequency.  There is no crankshaft or rod - the piston is
driven directly with solenoid coils.  Because there are no bearings and the piston
floats on a cushion of refrigerant, there is almost no friction involved.  You can
hear the piston continue resonating for a moment after power is removed.

The control box itself is 12 volts but the unit comes with a built-in 120volt power
supply.  Mine run equally well directly on 12 volts or via an inverter.

The chest format holds a remarkable amount of food.  I had two of 'em in my semi for
the year I drove over the road.  I'd cook up a month's worth of food at a time,
vacuum pack it and freeze it.  The freezer would hold all that.  The fridge held at
least a 12 pack of drinks plus all the usual stuff you'd refrigerate.

If the -45 isn't big enough then there's the -65.  I was tempted but it's too big for
one person to handle.  Strictly a 2 person job to carry it, even empty.  It would be
perfect for a fixed location, however.

The only teeny-tiny negative that I've observed is that one of the units occasionally
quits cooling.  The compressor runs but vibrates a bit more than normal.  Turning it
off, thawing the box and turning it on resolves the problem.  I suspect that there
may be a bit of moisture in the refrigerant that is freezing and plugging the cap
tube.  The other one never does that.  It's not a problem as long as I remember to
designate the problem child as my refrigerator.

I chatted with the propane delivery dude a few minutes ago as he delivered gas to a
neighbor.  Today's price is $2.50 a gallon.  For me, at least, that would be a major
reason NOT to use an absorption 'fridge.

John