found thread because i need info on fridge

[ricklapointe]

hi 
i need a quick and easy answer
do i really need a 12 volt overpriced fridge if i have the capacity of 6 big golf cart batteries on board with solar panels.
Or can i just use a couple of dorm fridges with there compressor flipped upright so i can use as chest fridge/ freezer? and would it be advantageous to put each one on its own inverter rather than one big one?
thanks

 

[highdesertranger]

Welcome Rick to the CRVL forums! To help you learn the ins and outs of these forums, this "Tips & Tricks" post lists some helpful information to get you started. We look forward to hearing more from you. I will let others comment before I give my 2 cents on the fridge. highdesertranger

 

[Almost There]

The problem with using regular dorm style fridges off of a battery system is that in addition to the power needed by the fridge, the inverter itself uses power as long as it's turned on. Depending on the inverter it can be somewhere around 10 to 20% of the inverter rating (not what you're using, the rating).

Sooooo, in addition to a higher power usage of a dorm fridge, you also have to add in the power usage of the inverter itself. Even when the fridge is not running, the inverter is still drawing power.

A 12V compressor type fridge uses less power than the dorm fridge would alone, let alone when you add in the usage of the inverter.

You might save money on the fridge but then add in the cost of the inverter and THEN add in needing a bigger battery system to sustain the higher power draw and you're right back to square one.

The other advantage of the 12V compressor fridges is that they are meant to be portable. How durable a dorm fridge is when used in a mobile dwelling remains under discussion. Personally I wouldn't expect the same longevity, particularly if you're intending to boondock which usually involves going down rough roads/trails.

 

[jimindenver]

You can do a lot with solar as long as you have a lot of solar to do it with. So that begs the question of how much solar do you have and can it produce more power than what you want to run needs?

There are more efficient residential mini fridges like the Edgestar 3.1 ft, two door that is rated at .64 amps at 120Vac. They cost more though. Choose right and you can save half and get a different brand that pulls .8a instead.

While I have seen inverters that can pull as much as 6a while in standby, I know there are some that pull much less. Then there are those like mine that will shut themselves down when the fridge does not call for power

All this is of course if you already have the big bank and big solar. It's cheaper in the long run to get a 12 volt fridge than it is to build out that kind of solar and carry that kind of bank. Ask me how I know.

 

[ricklapointe]

H i Jim
What is the make and model of your inverter?
I was planning on adding a total 2 extra inches of (enclosure) around the entire dorm fridge and 3 inches on bottom,making it as insulated as possible . The 3 units will be stacked one on top of each other and mounted on commercial style tracks so that they will be pulled out from the enclosure only when needed.
I will incorporate a chimney style vent on the back side of the enclosure to move the warm air out, either outside in summer or in in winter. Possibly a small computer fan on a thermodisc to sense hi heat.
Thanks in advance !

 

[Trebor English]

Propane ammonia absorption fridges generally need to be very close to level.  Compressor fridges don't depend entirely on convection to move fluids inside so they tolerate far from level operation.  There is a limit.  When the compressor is running and the tilt causes liquid refrigerant to enter the cylinder of the compressor bad things will happen.  The sudden change of compressor pressure will cause issues.  I would not rotate a dorm fridge 90 degrees without further investigation.  

In my experience tiny fridges have the hot freon pipe, condenser, welded to the inside of the case.  When running the entire top and both sides get hot.  That can't be insulated.  I added insulation on the inside.

 

[Trebor English]

  would it be advantageous to put each one on its own inverter rather than one big one?

I have an electronic thermostat.  I use the thermostat relay to turn on the inverter.  The thermostat relay is wired across the inverter on off switch.  With two fridges two inverters would be required.  

With a low voltage disconnect turning off the thermostat that turns off the inverter, turns off the compressor.  A huge switch to turn off the system at the highest power point, dc input to inverter, will cost in price of switch and an additional amp to keep the 100 amp continuous duty relay turned on.  Or don't bother with all that.  You don't need a low voltage disconnect if your battery and solar array are huge.

 

[highdesertranger]

my question is, how much is all this going to cost you? my guess when all is said and done you are going to be very close to a 12v fridge. if you shop around, buy used, or wait for a sale 12v units can be had fairly cheap.

I tried a dorm fridge. I also tried a 3 way, a peltier cooler, ice chests you name it I tried it. why? because I thought 12v units were too expensive. let me say this from experience, if I would have gone with a 12v unit right off I would be dollars ahead. my 2 cents. highdesertranger

 

[DLTooley]

JiminDenver and HighDesert Ranger are two of the most respected voices on this forum. Personally, I'd try it if I had the 120v device ready to go and wasn't buying it new. You do need to keep it in standard orientation.

 

[John61CT]

The super-efficient 240AC fridges sold in better-regulated nations will work just fine.

But we need a way to get them here doesn't cost as much as the product itself.

Meantime I agree, save your pennies and look out for bargains, eBay & CL as well as retail

 

[jimindenver]

Rick, I use a Trip-lite PV1250fc industrial inverter.

If by dorm fridges you mean the little cubes, I have found those to be the least efficient of all the mini refrigerators. The are built to a price point and almost always have a draw of 1.5a at 120 Vac = to 15a at 12v. It's why I suggest the models I do because they offer 2-3 times the space for half the consumption.

You can not insulate the sides and top id you do not see the condenser coil in the back.

 

[tx2sturgis]

Short answer: It wont work.

 

[Trebor English]

Short answer: It wont work.

Longer answer: Mine works.  

https://vanlivingforum.com/showthread.php?tid=27624 

I had the 100 watt panel, the Harbor Freight inverter, now $26, and the 75 amp hour starter battery upgrade.  The fridge was $80, the thermostat $5, and the added insulation about $20.

It is under 13 amp hours per day with 90°F temperature in the van.  It goes 3 days with zero electricity from the battery.  

The original poster wants two fridges rotated onto their backs on slides and a bunch of batteries.  That may not work.

 

[tx2sturgis]

The original poster wants two fridges rotated onto their backs on slides and a bunch of batteries.  That may not work.

That's what I was referring to. New dorm fridges often use R600. As soon as the OP bends the copper tubing to 'flip' the compressor, a flammable leak could occur.

I was answering the entire plan of attack, not pieces of it.

 

[wmyers4u]

seems like a lot of electricity needed to run two of them, 800 to 1000 watts of solar and 6-700 AH battery bank would probably safely do the trick.

You are on your own with playing god with the compressors though

 

[wmyers4u]

seems it'd be easier to convert a deep freezer with a divider to keep top items from freezing