Small Residential Freezer

AStinker- wrote:
Thanks for all the input guys. No doubt the 12v is best energy wise but the $1000.00 extra is hard to justify. Can do a lot of solar or extra batteries or gen time for that $$$.

I think what I am going to do is buy from a box store, fill it at least half full with jugs of water, plug it into Kw meter & see what it does.

I approached this problem from a different end, and simply didn't buy a generator. So $1,000 or $2,000 has been saved already and now it's hard for me to justify spending that much on a generator and charger only to have keep on spending on gas afterwards :) ... Right now it's a math of using propane VS getting a 12V fridge, since my solar allows it. Not even a "budget math", but rather a convenience issue because propane is still cheap, but burns out very quickly with fridge.

Don is right about abrupt increase in energy at the freezing point. You might end up using it as an ice chest, freezing it at home with gel packs and then trying not to open it too often.

My guess is it will run contineously for over 24 hours to freeze all that water, then the cycle times will become shorter and shorter until it reached equalibream, that is heat gained equals heat removed. This is assuming you start with the box at ambient temp.

In the beginning there were Encyclopedias. Now we have the wobbly wide web.

In this case, because water takes so darn much energy to freeze, it means we don't really need to worry about a one night excursion into the land of freeze.

AStinker- wrote:
How do you keep track of all this good information you put out? Photographic memory?

Yes sir I agree, intended to let the water freeze before getting any meaningful numbers.

But I did not know "It takes the same number of btu's to drop the temperature of one pound of water from 176 f to 32 f as it does to change it from water to ice at 32 f."

How do you keep track of all this good information you put out? Photographic memory?

Hi AStinker,

You can have any two of simple, easy or cheap, but not all three.

The test you propose is flawed.

It takes the same number of btu's to drop the temperature of one pound of water from 176 f to 32 f as it does to change it from water to ice at 32 f.

I'd suggest plugging in with the water in place. Wait until the water freezes. Then do the kill-a-watt reading over a 3 day period.

Thanks for all the input guys. No doubt the 12v is best energy wise but the $1000.00 extra is hard to justify. Can do a lot of solar or extra batteries or gen time for that $$$.

I think what I am going to do is buy from a box store, fill it at least half full with jugs of water, plug it into Kw meter & see what it does. Invest, Investigate then crunch the numbers.

Seems nothing is ever simple, easy or cheap. Why do I always have to pay the piper!!!

MEX.. I'm not so sure about vacuum panel insluation,, (Standard thermous bottle uses this kind of thing, which is why it's also called a vacuum bottle if you wish to use the proper name).

I recall back about 1970 give or take a few they came up with a "Super Insulation" basically it is layer after layer of aluminum foil and paper sandwitched together...

on the TV they make a cube, put a live birdlet inside, boil it a while and open the cube and let the still happy bird out.

Of course today you can't run a commercial like that.

AStinker- wrote:
I would think 90 amp hours in 24 hours is pretty good. I'm looking at a 5 cu ft partly because smaller freezers the annual kWh were almost as high. Sorry but guess I don't understand how insulation quality would help in this calculation.

Perhaps my answer sounded too simple. It is difficult to tell exactly how much it will draw. 90 AH per 24 hours is not uncommon. And it can also be anywhere from 70 AH per 24 hrs on a cold day with no door openings to 120 AH when it's hot outside and you keep on adding warm food in there. Lower priced small frigs are usually less efficient per cu.ft. than bigger and/or more expensive models.

Insulation is important around the whole fridge body, but this factor is more relevant to portable and built-in 12V models like Engel, Sundanzer, Tundra (aka Waeco aka Dometic), Novakool, Isotherm etc. They usually have less insulation (= less thickness) than residential 120V units, so they benefit more from added insulation. Realistically, added insulation is a 2" or 3" block foam, the thicker - the better. Vacuum panels is more a dream than something that people use in Rvs.

Well insulated 5-6 cu.ft. 12VDC fridge will draw about 30%-50% less than similar size 120V residential model, and adding insulation around residential won't help much because they usually have enough insulation already.

What makes 12VDC models different is that they use a DC compressor with zero startup current, and there is also zero inverter loss because they need no inverter. This is the direction that you should consider if you want 3 day camping with minimal use of generator.

MEXICOWANDERER wrote:
Opinion: This would never be the answer for me. Not when boondocking and losing money on recharging like there was no tomorrow.

x2.
Residential fridge running longer than a day or two, means a generator.

Edit:
Ops - have just noticed that you wanted a freezer - not a fridge. Then, 12V chest freezer is what I would get. Sundanzer, Engel, Steka, Dometic, Novakool. Most 12VDC line-ups have chest freezers.

For what it's worth (FWIW). We have a 1.5 or 6 cu.120V freezer for bringing fish back from FL and it runs on a 1200 watt inverter and the batteries charge while driving and the Auto alternator keep up with charging OK until I get to a shore line. Boon docking, I wouldn't want to run it longer than overnight on the batteries. Even though I have deep cycle batteries I don't like to run them down any less than 50%.
I will admit that I have never calculated the usage against supply.

One recommendation.. IF you are using an inverter to power a residential type fridge or freezer or any other 120 volt device.

Use 10, not 12.6 as your battery voltage..

here is why.

First, it really makes the math easy. I mean in all of mathmatics NOTHING is easier than multiplication by or division by 10 unless it is adding/subtracting zero.

Second. the inverter is less than perfect, 100 watts in, at the most gets you 90 out, so... we just lost 10%, there is also loss in the cables, wires and connectors, Way more than you might think. The result is that using 10 as the battery voltage comes way closer than 12.6 does.