DIY: How to make your own 12V Fridge

[ahh_me2]

bcbullet, which model of grape solar is this?
I can only find one on amazon atm it's 5 cu/ft and there are no tech specs anywhere, the model is GS-UF-5-Fab one Glacier

 

[DannyB1954]

Some inverters like the one I use have a load sensing feature. Sans that feature that would be a good way to go. Thank you

Another option is to have a relay that feeds the inverter with 12 volts. Have that relay triggered by the fridge thermostat. Leave the inverter switch on. 
You can bypass the thermostat that is in the refrigerator and then use that thermostat to power up the relay. Give the thermostat 12 volts from the vehicle. When it closes the power goes to the relay that feeds the inverter. The inverter comes online and the refrigerator cools, (because the thermostat was by passed). When the thermostat is happy, it opens and the relay drops out shutting down the inverter. Power to the refrigerator shuts off. No power is used when the refrigerator is not cooling.

http://www.ebay.com/itm/401111987343?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

 

[surfmore72]

Another option is to have a relay that feeds the inverter with 12 volts. Have that relay triggered by the fridge thermostat. Leave the inverter switch on. 
You can bypass the thermostat that is in the refrigerator and then use that thermostat to power up the relay. Give the thermostat 12 volts from the vehicle. When it closes the power goes to the relay that feeds the inverter. The inverter comes online and the refrigerator cools, (because the thermostat was by passed). When the thermostat is happy, it opens and the relay drops out shutting down the inverter. Power to the refrigerator shuts off. No power is used when the refrigerator is not cooling.

http://www.ebay.com/itm/401111987343?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

This guy is doing the same thing.   Nice write up too!

 

[Kaytown]

Just A noob here. I lightly skimed this thread but has anyone thought of or tried a super efficient DC compressor ? Example being (hope I'm not breaking any link rules here): 
http://m.ebay.com/itm/301990969884

My basic general knowledge here and the proposed 12vcd requirements led me to find this part being 12/24vcd.


Granted all this is from a noob prepper and my very first post here.  Ignore /delete as nessary

 

[ViaVacavi]

Just A noob here. I lightly skimed this thread but has anyone thought of or tried a super efficient DC compressor ? Example being (hope I'm not breaking any link rules here): 
http://m.ebay.com/itm/301990969884

My basic general knowledge here and the proposed 12vcd requirements led me to find this part being 12/24vcd.


Granted all this is from a noob prepper and my very first post here.  Ignore /delete as nessary

Yeah, I've thought about rolling out my own fridge with a 12VDC compressor, but it's out of reach for most hobbyists.  First you need the equipment (compressor, evaporator, condenser and a device/design that creates a pressure drop to separate the low and high sides of the refrigeration cycle, vacuum pump to evacuate the system, refrigerant and lubricant.. etc).  And even with all of that you're not guaranteed an efficient fridge if all of the components aren't selected and sized properly to work together.  It's much easier,cheaper and less risky to use an already working design and improve on it (insulation, 12v conversion via inverter, etc).  

That's not to discourage you, I think it would be a great project - and there could be some really huge advantages - such as locating the condenser outside of the van for instance.  I'm only speaking from the perspective of keeping things simple so they can easily be reproduced by others

 

[ViaVacavi]

Converting a Home Depot Magic Chef 3.1 CuFt Refrigerator/Freezer to a fairly efficient 12v refrigerator

Below I'm going to detail exactly how I converted my refrigerator at a total cost of about $150 (including the fridge!) to run off my battery bank.  The completed conversion has been using between 30-33 Amp-hours per day from the battery bank.  While this is a little higher than many (but definitely not all!) true 12v refrigerators, it's still not bad at all, especially for a fridge this size and with a separate freezer compartment.

But before we start, I want to make a few notes about efficiency.  The fridge that I converted (3.1 CuFt Magic Chef refrigerator/Freezer combo) is definitely not one of the more efficient fridges to convert - for one, the walls are fairly thin.  The condenser is mounted beneath the skin and not really separated from the evaporator, which isn't efficient either - and insulating the outside would only make it worse.  More efficient designs would have the condenser tubes on the back.  Even better, the cheap, small chest freezers would be even better due to the better insulation.  But this just shows the basic technique and shows that there is promise in the conversion.



Parts:
- Bestek 1000w inverter link
-Magic Chef 3.1 min fridge/freezer (prices vary, but the last one I bought was on sale at $119.  There is a 3.5 CuFt model that is refrigerator only for $99 that would work well too and has similar wiring)
- 2 Bosch style automotive relays link
- 4 terminal strip link
- 2 position terminal strip link
- Various spade connectors, zip ties, etc.

Overview
[img=640x452]http://i827.photobucket.com/albums/...-4e27-8a9c-b0956b8e7eb9_zpscdm61ofm.png[/img]
It's hard to see here in this image (look at attachments below for full sized pdf), but there are 3 wire bundles that come together in the stock fridge.  The "Power bundle" is the bundle of 3 wires coming from the power cord.  The "Fridge bundle" is a bundle of 4 wires heading into the fridge body and up to the thermostat.  The "Compressor Bundle" is a bundle of 2 wires that go to the compressor.  The schematic included shows how these 3 bundles connect together on a stock unit.  Our goal is to add a few components, and re-arrange the wires so that the thermostat will control the firing of two automotive relays - one that commands the (modified) inverter to turn on, and one to connect the compressor to the 120v power.  For those looking for even more simplicity, the two relays can be reduced to one single double pole relay if you want, but I chose to stick with automotive relays due to their high availability everywhere

[img=640x445]http://i827.photobucket.com/albums/...-48d7-9df9-5751611413ef_zpswvutafhv.png[/img]
The above schematic shows how the new components (namely two automotive relays (R1 and R2) and an optional cooling fan) are wired into the fridge.  I'll outline this step by step in coming posts.

Modifying the Inverter
Since this design utilizes an inverter, we must modify the inverter so that it can be switched on and off remotely.  This is very easy on the Bestek model listed above.  This will also allow a manual switch to be wired in parallel to the the leads from the modified fridge, so that we can switch the inverter on anytmie we want to.
[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_143109_zpsolymqsdr.jpg[/img]
First, the On/Off switch popped right out with a screwdriver. This is as easy as it sounds with this inverter.

[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_143216_zpsdeewrtys.jpg[/img]
I then drilled mounting holes for the terminal strip that was going to be installed.  Common sense applies here - make sure the inverter is not connected to anything.

[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_143155_zpsrdvvxcnv.jpg[/img]
It's also a good idea to choke back on the drill bit as much as possible so that it doesn't damage the inernals of the inverter when it emerges from the other side.  As you can see above, I tried to expose as little of the drill bit as possible for this step

[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_143730_zpsvjrsahdp.jpg[/img]
The terminal strip is then mounted using the mounting holes, and the two leads that used to go to the switch are attatched to one side of the terminals.

After this step, the inverter is mounted as normal inside the van.  Later when we are done converting the fridge, I'll show you how to connect it to the inverter.

 

[ViaVacavi]

Modifying the Fridge

Now that we are done modifying the inverter so that it can be easily remotely switched, we can start on the fridge.  This can literally be done in 20-30 minutes if you have all the parts you need!

1) First we are going to gather the parts needed: a few Yellow wire nuts, 2x Bosch-style automotive relays, 4-position terminal strip, zipties and electrical tape. You'll probably want some good wire cutters, a razor blade, a drill and a screwdriver available.

2) There are 3 wire bundles to the fridge. We are now going to separate these 3 bundles.  In the end, we will have a "power bundle" (Black, white and green wires from the power cord), a "Fridge bundle" (Black, white, red and green wires going into the fridge to the thermostat) and a "compressor bundle" (red and white wires going to the compressor).  It goes without saying, but make absolutely sure the  refrigerator is unplugged before doing any of this!

[img=640x1138]http://i827.photobucket.com/albums/...avi/IMG_20160901_151209_zps3jmexz6n.jpg[/img]
All the bundles come together in a junction box to the left of the compressor.  Use a long screw driver to remove the two screws.  There will be enough slack in the wire bundles to pull the whole assembly out the back once the screws are removed.
[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_151254_zpsaj74yadz.jpg[/img]

[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_151317_zpseull13qx.jpg[/img]
Pry the junction box apart with a screw driver

[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_151341_zpsnpjur8fe.jpg[/img]
This will expose the wiring and you'll see how the 3 bundles are crimped together.

3)  Now we're going to cut some wires.  Once again, be absolutely sure that the refrigerator is not plugged in before doing this step!
A) Cut the white wires as close as possible to the crimp nut at the end.
B) Cut the red wires as close as possible to the crimp nut at the end
C) Cut the black wires as close as possible to the crimp nut at the end
D) You will be left with 2 green wires that haven't been touched yet.  One comes from the "power bundle" (power cord), and the other goes to the "fridge bundle" that enters the housing of the fridge.  Cut ONLY the green wire going to the fridge bundle, and leave the green wire to the power bundle untouched.  The reason for this is that since the changes we will make will allow the thermostat to operate at 12v instead of 120v, the ground wire is no longer needed.  While we could technicaly not cut any green wire, I prefer to eliminate it here because it could tie the chassis ground of the vehicle to the earth ground of the 120V supply, which I prefer to do in a dedicated location when necessary.
[img=360x640]http://i827.photobucket.com/albums/...0160901_151505_zpsc3wupmdr.jpg~original[/img]
Here is the Fridge bundle after cutting.  Notice that the green wire in this bundle has been cut!
[img=360x640]http://i827.photobucket.com/albums/...avi/IMG_20160901_151523_zpskrcau1mc.jpg[/img]
The lower bundle in this picture is the power bundle (Black, white and green).  Notice that the green wire was NOT cut in this bundle!

[img=360x640]http://i827.photobucket.com/albums/...avi/IMG_20160901_151513_zpsewoiurjw.jpg[/img]
Lastly, the compressor bundle has a red and a white wire.



4) Label the Bosch relays. Label one as “R1”, label the other as “R2”.  This can be as fancy as a using a nice label machine, or as simple as using masking tape and a marker.   We will not be using the red wire from either R1 or R2, so you can snip those off if you want to to make things less confusing going forward (recommended).  After this is done. we will mount them on the left side of the fridge near the bottom of the fridge where there the opening is that houses the compressor (see picture below).  If you try to mount these higher up with screws, you may puncture one of the inner coils and ruin the fridge, so pay attention to the mounting location shown below.
[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_151931_zps4ow4uq8b.jpg[/img]


5) Mount the terminal strip right below R2 (see pictures below). Mount the fan so it blows in towards the right side cavity of the fridge using 2” drywall screws (see pictues of fan location later in instructions on the completed conversion).  Basically, the relays and the terminal strip are mounted on the left side of the fridge (looking from the back of the fridge) and the fan is mounted on the right hand side of the fridge.  The fan is optional, but I feel that the additional air movement around the compressor, expansion chamber and exposed tubing will increase the efficiency of the refrigerator
[img=360x640]http://i827.photobucket.com/albums/...avi/IMG_20160901_152146_zpsehcavyze.jpg[/img]

 

[ViaVacavi]

6) Attach the blue wire from R1 to terminal 4
[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_152257_zps21akd84q.jpg[/img]



7) Attach the yellow wire from R1 to terminal 3
[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_152400_zps51gegl0g.jpg[/img]



8) Take the blue wire from R2 and connect it to the black wire in the power bundle
[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_152528_zpshczavxhf.jpg[/img]



9) Take the yellow wire from R2 and attach it to the red wire in the compressor bundle
[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_152643_zpsq6bftlt9.jpg[/img]



10) Take the white wire from the compressor bundle and attach it to the white wire in the power bundle
[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_152756_zpskohlzflo.jpg[/img]



11) Take the black wire from the fridge bundle and attach to terminal 1 on the strip NOTE: You may need to trim back the flexible conduit covering on the fridge bundle to get enough slack wire to work with
[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_153011_zps0ooui5lq.jpg[/img]



12) Take the white wires from both R1 and R2 and attach them to the red wire in the fridge bundle (NOTE if you’re connecting an optional fan, connect the red fan wire to these as well)
[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_153908_zpsiuhqnih7.jpg[/img]



13) Join the black wires from both R1 and R2 and the white wire from the fridge bundle, along with a scrap piece of wire with a wire nut. The scrap piece of wire will then be attatched to terminal 2. (NOTE if you’re connecting an optional fan, connect the black fan wire along with these)
[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_154241_zpsu1yomquh.jpg[/img]

14) Use some zip ties and/or eleactrical tape to clean up the bundles of wire.  The picture below shows a completed conversion and shows the entire back of the refrigerator (note the fan location on the opposite side of the other components)

 

[bcbullet]

bcbullet,  which model of grape solar is this?
I can only find one on amazon atm it's 5 cu/ft and there are no tech specs anywhere, the model is GS-UF-5-Fab one Glacier

Sorry...missed your post. I believe Homedepot carries it in the States. It is a [font=Arial, sans-serif][size=large]Grape Solar GS-CF-2.75-Fab-1 [/font][/size]

 

[ViaVacavi]

Converting the Fridge Light

Since the light bulb in the fridge is a 120V household bulb, and we've converted the control circuit to 12V - we need to convert the bulb.  This step is optional.  The converted fridge will still work, but you won't have a working light in the fridge.  These steps will show you one method to remedy that.

We basically have 2 options:
1) Take the internal housing off of the thermostat and find a way to replace the 120V screw-in socket with an automotive type
2) Find a way to adapt a 12v automotive bulb to a 120V screw-in socket.

For simplicity, I chose option 2

[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_160407_zpszifira0c.jpg[/img]
First I unscrewed the 120v light bulb from inside the fridge.  There is a clear cover over it secured with a small philips head screw that must be reoved first


[img=360x640]http://i827.photobucket.com/albums/...avi/IMG_20160901_160427_zpsp5bfjsmk.jpg[/img]
I used channel-lock pliers over a trash can to break the glass.  If you do this, please wear safety glasses and/or place a rag over the top of this while breaking the glass to protect your eyes!  I found that the glass breaks very easy, and any sharp pieces around the metal screw-in part chips right out with no issues


[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_160512_zpsm2jqzuju.jpg[/img]
You should be left with two main wires sticking up, with a mess of fillament tangle in between.  Remove that tangle of fillament.


[img=360x640]http://i827.photobucket.com/albums/...avi/IMG_20160901_160558_zpsrd9nofyw.jpg[/img]
That should leave you with just the two main wires sticking out.



[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_160801_zpsfgcull61.jpg[/img]
Next I took a T10 automotive LED bulb



[img=640x960]http://i827.photobucket.com/albums/...avi/IMG_20160901_160828_zpslampsh1w.jpg[/img]
And straightened the wires out on that too

Now the bare wires on both the 120V screw-in part, and the T10 automotive bulb have a coating on them that solder doesn't like very much.  I simply scraped the wire thoroughly with a razor blade to remove the coating.



[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_162431_zpsx5ds6q97.jpg[/img]
Then these were soldered together.  Note that the LED bulbs that I used were polarity independent (it doesn't matter which side is positive or negative).  Your results may vary, but I would imagine that most T10 automotive LED replaceents will be the same.



[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160901_162718_zps1kvrjxu3.jpg[/img]
I then used some silicone caulking that I had on hand to cover the exposed wires and give the assembly a little structure.  After that dried, I had no problems screwing the converted hillbilly bulb right back into the socket.



[img=640x1138]http://i827.photobucket.com/albums/...avi/IMG_20160901_171618_zpshe9lwxsv.jpg[/img]
The resulting light is so much brighter and cleaner than the dingy orage glow of that old incandescant bulb!

 

[ViaVacavi]

Connecting the Converted Fridge

Connecting the fridge is pretty simple.  The normal 120V plug end will plug into the modified inverter.  Then the four terminals from the terminal strip that was added to the fridge go as follows:

1 12V+ supply
2 12V-  supply
3 to inverter terminal position 1
4 to inverter terminal position 2

 

[ViaVacavi]

I'm out of time for the night, but as soon as I get the chance I will show how to make a simple inexpensive automatic transfer switch. When used it will essentially make this converted fridge a 2-way fridge, automatically using shore power when available, or falling back to the inverter when shore power is not available!

I've done this conversion now on two refrigerators with great success!

 

[SternWake]

Most t 10 leds are polarity sensitive. Do test them bfore wiring. I use a red sharpie on bulb base to denote +.

Also some of these t 10 led bulbs might fall apart when those wires are straightened.

 

[ViaVacavi]

Reliability Update

Just wanted to post a quick update.  These cheap Magic Chef refrigerators have been used in two vans so far (one for three months, the other for about a month).  During this time, they have seen plenty of mileage, daily use, on and off road use (including driving up a VERY steep dirt mountain road).  These fridges have held up fine so far without a hiccup.  Now that the temperatures are starting to drop outside, I"m starting to see daily electric usedrop below 30 amphours per day, which I'm very happy with.

While not very scientific, I have done some tests on how the fridge performs running on non-level surfaces.  The results are quite surprising!

[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160911_195033_zps0g9uabrr.jpg[/img]
Here is how one of the vans is nearly always parked.  This is a slight 2-3 degree angle, and the fridge has never had an issue with this


[img=360x640]http://i827.photobucket.com/albums/...avi/IMG_20160911_192237_zpsbsysb7hh.jpg[/img]
For my tests, I propped one end up with the long edge of a 2x4 (elevating one side 3 1/2" higher than the other side)
It should be readily apparent that this is an angle that just about anyone would reject for staying in their van.

[img=640x360]http://i827.photobucket.com/albums/...avi/IMG_20160911_192916_zpskovoqebt.jpg[/img]
Not an exacting measurement, but my builder's square shows 20+ degres of tilt (not counting the couple of degrees of tilt on the driveway where it's parked)

[img=360x640]http://i827.photobucket.com/albums/...avi/IMG_20160911_194542_zps9abpgytu.jpg[/img]
I put a temperature gauge in the refrigerator compartment to see if there was any loss of cooling

[img=360x640]http://i827.photobucket.com/albums/...avi/IMG_20160911_194535_zpsyobbr5f7.jpg[/img]
At the end of the test, the fridge maintaned the same temperature that it started out at.  The compressor cycle times were identical to running on a level surface.  This shows pretty well that there really isn't a loss of efficiency at all, even at a 20+ degree angle (probably closer to 25 degrees when accounting for the unlevel ground where the van is parked).

I'll keep updating the thread from time to time with reiability updates so that we can get an idea how long these refrigerators will last in a mobile application - but indications so far are very very promising

 

[Headache]

I really want to thank you for this thread! I don't understand half of it(I do not have an analytical mind) but what does excite me is that people like you figure out the good, fun and efficient stuff which people like me also end up enjoying.

I have an 8 cu ft fridge which is just the right size for my use which also includes a small freezer. I don't have a clue what that would be in quarts. I can't even begin to imagine what kind of juice it would use and I'm not even sure doing what you did with a small one would be possible(relative to being practical to use, not if it can be done). It's an older version of this one:

http://www.compactappliance.com/Ava...nt-Refrigerator-Black-Platinum/RA7316PST.html

I know a lot of RVrs have been making the switch to household appliances and they have been holding up rather well despite the fear of them being bounced around. The only time I have ever had to wait to start one was if it was laid on one of it's sides, not if it was upright bouncing around in a delivery truck.

 

[ViaVacavi]

I really want to thank you for this thread!  I don't understand half of it(I do not have an analytical mind) but what does excite me is that people like you figure out the good, fun and efficient stuff which people like me also end up enjoying.

I have an 8 cu ft fridge which is just the right size for my use which also includes a small freezer.  I don't have a clue what that would be in quarts.  I can't even begin to imagine what kind of juice it would use and I'm not even sure doing what you did with a small one would be possible(relative to being practical to use, not if it can be done).  It's an older version of this one:

http://www.compactappliance.com/Ava...nt-Refrigerator-Black-Platinum/RA7316PST.html

I know a lot of RVrs have been making the switch to household appliances and they have been holding up rather well despite the fear of them being bounced around.  The only time I have ever had to wait to start one was if it was laid on one of it's sides, not if it was upright bouncing around in a delivery truck.

I'd be more than happy to help you do a conversion.  I would say first step would be to see how much energy it currently uses.  If you can get your hands on one, a kill-awatt meter would help a lot.  They can be bought very cheap on Amazon.

Once we can determine power use in its current state, we can come up with a reasonable estimate of how many amp-hours per day it would use from a battery bank.  This should be enough information to determine if a conversion is feasible.

Additionally, it would be nice to know if it has an external condenser or not.  Basically, if it has some sort of grid of tubes on the back, it has an external condenser and could benefit easily from additional insulation.  If the condenser is internal, this tubing will be missing from the back and you'll find that the side of the fridge get warm when running.

8 CuFt is around 240 quarts.  That's a huge fridge for a van!

 

[ViaVacavi]

Just updating the tread. It's been another month of trouble-free operation from the converted fridge. I just started tests on a different (cheaper) inverter that can be used for this setup (about $40). I'll share information on that inverter once I can see how it operates over time

 

[Telcobilly]

Great info,  thanks!  I've been living the cheap rv life in a big truck.  All of the household appliances I've bought,  including fridges, have held up very well.  I'm still using a second hand 1500watt Roadpro inverter that I bought from another driver for $50 over 5 years ago.
I'm very self contained with 8 sport bottles for water,  a clothes line to hang my clothes after washing them at the truck stops,  camping toilet when I have to go NOW.  I'm doing another 2-4 years and then I'M OUT.

 

[ViaVacavi]

Great info,  thanks!  I've been living the cheap rv life in a big truck.  All of the household appliances I've bought,  including fridges, have held up very well.  I'm still using a second hand 1500watt Roadpro inverter that I bought from another driver for $50 over 5 years ago.
I'm very self contained with 8 sport bottles for water,  a clothes line to hang my clothes after washing them at the truck stops,  camping toilet when I have to go NOW.  I'm doing another 2-4 years and then I'M OUT.

Thanks for sharing how similar appliances have held up over time.  I know that the 6 months of trouble-free operation isn't much to brag about yet, but early indications for me so far are excellent

 

[ViaVacavi]

Jed from IntoTheMystery13 stopped by to tour a couple of my van builds last month, which includes one of the converted fridges too! Check it out!