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DIY: How to make your own 12V Fridge
> Having the inverter on full time used more watts than the actual refrigerator did, the fridge used 360W a day and the inverter used 400W a day.  Now that I can used sleep mode the whole system uses 450W to 500W a day.

Note that watts per day does not make sense, same as amps per day.

I'm guessing you mean watt-hours per day?

If this is at 12V then the range is 30-42-63AH per day.

A very efficient, quiet and long-term reliable inverter sized right for the load seems to be the key to this idea, so getting comparisons on specific units that are reasonably priced (Magnums can be more than an Engel) would be very helpful.
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Carv Like the nice clean wiring. Think these dorm freezers are the way to go for these systems; takes a little more Craigslist shopping to get one for cheap but worth it. I love mine. Looking at the numbers and they are very similar to the big dollar 12V systems; has me sold on keeping it as my permanent fridge.

I like the sleep mode I have not seen one of those yet in action sounds like a good option for the future if my inverter ever dies.
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John,
Yes that is 500Wh in a 24hr period which is 42AH in 24 hours for both the inverter and fridge and since I have 520W of grid tires on my roof with a 30A mppt charge controller batteries where full by 11am every day.

Over night (dark at 5:30pm first light at 6:45am) so 13hrs no sun at all and running 12v interior LEDs and a 16ft Led rope light for 3hrs plus I used a total of 17.6AH


Aquatics, I totally agree!  
I got mine on CL for $70, I put plexiglass liners on the shelves for $20, and $15 for the temp controller.   I can run it at any temp I want considering it's designed to run at negative 14 to negative 21, so cold beer, frozen meat, Or just regular fridge duty I really don't think you can beat it for a $100

Like I said earlier, if you get a simple 2 terminal block and wire one side of on/off switch on the inverter to the separate terminals so each side/positive & negative are septate (just like vanvacari did in his earlier posts & pictures).  Then get a 12vDC STC-1000 digital temp controller, run the controller off the batteries directly and wire the cooling terminals on the temp controller to the 2 terminal block you wired in to the on/off switch ...AND....you now have sleep mode on your inverter ? for $17.

The inverter won't be on all the time but it'll save you a bunch of Wh

OR you could figure out how to wire in the switch so you can control the inverter on/off with the switch as well if you want the inverter to be under your control when you want and ran by the temp controller when you don't want to manage it.  This is how van vacari did it.
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If anyone's solar is switching to Float voltage - when the battery's deeply cycled overnight - in less than 4-5 hours of insolation, odds are good their bank's getting murdered by never really getting to 100% Full.

Which is (should be) defined by endAmps getting down to .005C before dropping from Absorb.

But that's a bit off-topic. . .
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Love the thread! 

I also have been looking into this kind of a setup and one of the things I was struggling with is the need for a large inverter to power the fridge due to the startup current. I noticed that you have thought about using a soft start capacitor for the compressor. What do you suppose the savings for power consumption will be by being able to use a smaller inverter? Here is a video describing the process of using a soft start (this one is more complex than a capacitive one). I love the idea of using a 12V relay to control the inverter, I may have to steal that. Another power saving measure (we're getting extreme here) may be to put a timer on the controller for say every 30 min to go on for 30 sec and check if there is a need to run the controller for the next 30 min. Yeah it's only 3W continuous, but power is one thing it's ok to be miserly about, right?

I've actually been considering putting 2 of these together for 2 separate variable units (i.e. dual freezers or dual fridges or one of each). If I get 2 different sizes (like a 3 ft and a 5ft) I can switch them around as things transition fridge to freezer etc. plus I have some redundancy  and I'm still under the cost of a tiny Engel or something. This of course assumes that space is not a main concern.
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Holy crap the electronic one the video is for is like $300, NOPE! I'll buy the dumb one for $15, lol.
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hello all , i am new here. found an article about this subject that didn't mention an inverter. just converting a 120 vac freezer to  12 vdc. after 35 + tears in a/c refrig. and electrical this didn't seem possible. the author must have been  lapse in their facts, anyhow the set up and freezer and the data seems to be good. emailed the site , waiting for response.i will get model of inverter and how it worked and relay info.

Mod edit. I edited out the link please no links until you have 10 posts.
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here's the link that I edited out,

http://shedheads.net/need-know-buying-12v-refrigerator/

a lot of misinformation in the article. I doubt they did the actual testing themselves. highdesertranger
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Redbeard, I wouldn't worry about a hard start capacitor.

I tested mine with a kill-A-watt and or was 1.35A on start up and then it'd drop to .9A after 20-30 seconds.

On the itc-1,000 DC digital temp control I mentioned before, you can set the restart protection delay time length so you shouldn't be re-firing it under high head pressure.

If your really that worried test it to see what it's pulling on start up.
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That reddit post was pretty awesome! Certainly makes me consider going the inverter route and a cheap chest freezer. My DC voltage will be 48 volts with my experimental Chevy volt battery pack so I either have to convert 48 to 24 volts for the fridge or invert to 120 volts.

Looks like I'll be looking for an upright 3.5 cubic foot chest freezer like this:
https://www.homedepot.com/p/IGLOO-3-5-cu.../203474226
I Just want to see some actual power ratings, not the energy guide posting. If the energy guide posting is anywhere near accurate, though, then that freezer draws just around .5 KWH a day. In converted refrigerator mode hopefully it draws less even with the losses from the inverter.

Might be a worthwhile experiment based on some of these results.
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