Making ICE! (home made fridge)

Grim Reaper

Expedition Leader
I sort of walked into a deal on some 24v AC units that were on some cabinets I was interested in. Little boogers are rated 986 BTU so really not powerful enough to cool and sizable space.

Well I look up the compressors and it turns out these things will run 12v as well. Its the same brand compressor used in the Waeco 110 but this one is over twice the output http://waecousa.com/page.aspx?p=proportref
http://www.rparts.com/Catalog/Major_Components/compressors/Danfoss/danfoss.asp They are used for making fridges on Yachts. :wings:

THis is what I have for the most part but it has a Air evaporator on it http://www.westmarine.com/webapp/wc...02&subdeptNum=230&storeNum=15&productId=61965


Now most portable fridges like the ARB Waeco and use a Roll bond Evaporator but this this is an already running A/C with an air exchanger. I was looking at swapping the evaporator for a Roll-bond but I was having problems winding somebody I knew to recharge it. I'm also a cheap bastard so I want to make this as cheap as possible. I may still swap it at one point because it will mean lower power consumption.
http://www.rparts.com/Catalog/Major_Components/compressors/Danfoss/danfoss.asp

So I got thinking about my home fridge and it uses and air exchanger style evaporator so I did a little experimenting. I took the lid off my cooler and stuck the evaportaor in it and used card board to seal up the rest of the hole so a LOT of thermal loss for lack of insulation.

The first test I ran the compressor with just the evaporator in the cooler with no fan on evaporator. Stuck a remote thermometer in the box and a probe thermometer I could move around. After about 40 minutes of run time it leveled out at about 43 Degrees. Just wouldn't drop below that with another hour of run time. I stuck my IR thermometer in the Cooler and got a temp of 16 Degrees F on the evaporator. :bowdown: But the lack of air flow through the evaporator just didn't get that cold moving around my poorly insulated box. I had 24v DC fan handy It ran half speed on 12v. Hung it on the side of the evaporator to move some air through it. Out put side was running 28 degrees and the warm side of the box got down to 30 in about 15 minutes. :wings:

Today I am going Cheap cooler shopping. I need something with Perfectly Vertical sides to mount the Set up on for further experimenting. The biggest thing after doing research is that most coolers have really crappy insulation. I may ultimately end up making my own box or adding insualtion to a ready made cooler.

From what I read if I make a air tight box using 2 inch blue board foam insulation it will probably have double the insulation properties of the typical cheap cooler most of us use. That should let me get down to the mid to low 20's in the freezer area.

I also need to down size the fan on the evaporator. I need it to draw less power and run a little slower to allow a little more time to cool the air moving through the evaporator. I think a Pair of CPU fans might do the trick.

Some how out of the 3 high end Fluke meters I have all have blown fuses or other problems so I couldn't get a current draw figure It may be an issue with the wat the compresso runs that it can't get started running through the meter. From what I read this thing will pull about 65 watts at full draw. Now the Compressor is capable of running variable RPM's So I need to investigate what it takes to make that work. Right now its looking like a $200 controller.


Making my own box with the air exchanger will also let me compartmentalize and make a freezer area and a refrigerator area within the same box since I can use duct work to move the cold around to control the temps.. :sombrero:

I have a couple Honeywell industrial thermostats with remote probes on scrap equipment I can lay my hands on to regulate the temp. I got these set ups as a bonus. All I was interested in was the box they were attached to. So my total cost on the prototype will be the box I build and a pair of CPU fans.... :wings:
 

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Grim Reaper

Expedition Leader
Well I went and bought a 70 Quart Extreme Coleman. http://www.cooler-store.com/coleman_xtreme_cooler_70qt_111_prd1.htm

I thought I would cut off the bottom and side just below the handle on one end and basically sink the Compressor assembly into the end. It would end up being the same size as the cooler and knock it down to about 50 Quarts internal.

After getting it home I don't like it.

First problem is fitting in my truck. I have an 8 inch high drawer/sleeping platform system I am installing in the truck. With the hight of the drawer and the hight and length of the cooler I cant get the lid open very far before it hits the factory roll bar in the back. I looked at what it would take to make the cooler slide out and I would have to make slides about 30inches long to get it out from under the roof so the top could be opened.

Then mounting this 10lb compressor assembly to the cooler is a major problem. ABS plastic is hard do glue so I really don't feel like I can make the assembly as strong as I want once I cut that corner off it. The compressor would have to mount to the filler panel. Then add that if anything leaks inside it may end up getting into the Compressor area.


I am going to take it back and get an Igloo Cube. http://www.cooler-store.com/igloo_ice_cube_cooler_48qt_9_prd1.htm

Instead of a 16 wide x 32 inch long box I will have a 17.25 inch square box with the compressor assembly adding about 10 inches to one end. The 1.25 inches in width is nearly ideal as well. The mounting will be much easier because I just need to make the hole for the evaporator to stick through. A couple long bolts into the chassis of the compressor tray and I'm set. If something spills it can 15 quarts before it gets to where I cut the hole for the evaporator to stick in.

I can clear the roll bar and get it open about double what I could with the other cooler and I still want to put it on a slide and I only need to make it slide about 18 inches if I install it compressor first so a normal off the shelf drawer slide will work. The lid hinge may also be longer lasting then the coleman.

The down side to the Igloo is I don't feel it is anywhere as well insulated as the Coleman extreme. I may be able to overcome that some. Have to see I will also have to take up a little more width (dog space) to fit it.

I may go exchange the coolers tonight so I can mess with it when I get home tomorrow. I would like to have it up and running by the end of the week if possible.
 

Grim Reaper

Expedition Leader
Finally got back to playing with this some today. Ended up with the 60 Quart Igloo Cube. Taller then I wanted for the 4Runner but for Prototype #1 I think it will be fine. Honestly for the Suburban its about perfect.

So after cutting a hole in the side of the cooler and a little modification I had a reasonably well insulated set up.

I found a lower power consumption fan for the box so I should be under the maximum draw that the Compressors control unit can handle. Right now I am just straight wired so no big deal. I may still put a Relay on the unit to control the fans.

I did more research and the unit has 4 motor speeds. As it was set up it is running on Speed 2. I think I may rig a switch were I can kick it into speed 3 For hot days.

I need to source a thermostat as well. I have one that will work but the who control would have to be mounted in the box. I would rather set it up on the cheap but as well as it is working so far there is a really sweet control that I could also install that would automatically control motor speed depending on how big the gap is between target temp and current temp. http://www.great-water.com/pages/Temptech/Temp_tech.htm

Its only 70 degrees today so not really a lot of thermal load to overcome. I wired it up and ran it for about 2 minutes to make sure it was all working.

After running for 10 minutes the top of the cooler is actually cold. It is not insulated very well. Just the roto mold hollow top.I think I may try to get some great stuff foam spray and see if I can fill it up some and get the R value up. The main box seems reasonably well insulated. It was thicker then I would have thought at about 1.75 inches where I cut through it. It is a expanding foam they used so minimal voids in it.

I still need to make the shroud for the compressor section as well.

Here is my findings

Ambient outside temp 70f

I had run the unit so my box temperature was 66f

After 5 minutes of run time box temp was 41f

After 8 minutes of run time box temp was 32f

after 10 minutes of run time box temp was 28f

after 15 minutes of run time box temp was 21f

It seems to settled out at 19f I think that will work out OK for the $40 I have in it so far. :bowdown:
 

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Grim Reaper

Expedition Leader
I stand corrected on minimum temp. It got down to 16f after leaving it for a while.

I have it fused at 5 amps so I think I managed to make my goal for power consumption. It has run for 1.5 hours and not blown the fuse. Need to get one of my meters fixed and see what it actually draws.

I think my biggest problem to overcome to make it more efficient will be insulation.

I measured the side of my car that is next to where I am testing the fridge and the car measures 71f I measured the side of the cooler and its 67f

I measured the center of the top where it has no insulation and it is 55F

The top has cup holders in it and they are 32f in the bottom and condensation has formed in them. So that confirms I need to get the insulation up on that lid to help lower the Duty cycle once I start using it.

I put a cup of water in to see how fast I could freeze it solid. 55minutes and it is almost there.
 

Pad

Adventurer
Great job!!!!
This is a project I will be trying! When time permits.
Love the store bought fridges but wow the price kills me.
I always thought 'if I could buy the parts I would convert a cooler myself.'
Huge thanks on the links!

Is there an award for "most ingenious, cost effective, home made 'thingy?"
Well you get my vote!!!!

Pad
 

Grim Reaper

Expedition Leader
Lynn said:
Hey Grim,

How'd this turn out?
Keeps Ice cream good and cold on the trail :)

I need to make some baskets for it but it works. I have enough cooling units to make 4 more. If I build my camper Burb one will permanently be installed in it. Thinking about gutting a garage sale dorm fridge and use this for the Airstream.
 

coronan

New member
Great Thread. I know this is an old one but very scientific. Progress was tracked.
I wish there were more photos and less broken links.

Any updates.

Thanks!!!
 

Ozarker

Pontoon Admiral
Many sailors build their own freezers and fridge. Usually top loaders. A box in a box with lots and lots of insulation, you'll find instructions on the cruising and liveaboard sites. Sorry, I don't have a link. Ebay has the componets as well. Good luck and nice rig. :)
 

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