# An idea to save electricity and have some modern conveniences



## townparkradio (Mar 30, 2010)

I have a theory.. this was originally going to be a rig as a gift to my wife's parents, but I want to talk about it first to bounce my idea off of others.

We all know heat rises and condensation tends to pool, correct? I present to you, a way to get a working fridge for a fraction of the cost involved normally. Your average drop down freezer is actually rather energy efficient... moreso than a fridge would be at the same temperatures. As I understand it, you want your average fridge to be around 36 degrees. I've owned decently sizable freezers before, and had noted they reach that temperature within a few minute of having been turned on, regardless of ambient temperature. It also holds it's frozen temperature fairly easily, if you're an idiot and leave the top open. A vertical freezer, not so much. So.. this tells me if you're living off the grid.. you should never be using a vertical fridge.. period. Secondly, it gave me this idea.

A simple thermostat relay inside the drop down freezer with the power cutoff at 36 degrees or below should actually turn the freezer into an INCREDIBLY efficient fridge. My only issue is that, for the life of me, I cannot devise a schematic to prepare such a thermo with a cutoff relay. There are some market solutions you'd think, but those are all made to turn a unit ON when a certain low temp is reached. As I understand it, this should draw like.. a few watts a DAY provided you don't leave it open for long. Drop down is inconvenient for a fridge but let's not kid ourselves... if you're willing to live off the grid you're already willing to give up things like "staring at the fridge and picking food out of it".

Anyone got any ideas here? The makeup of a thermostatic relay like this is beyond my skills... but then I'm probably doing it wrong anyway.. I'm fiddling with resistors and a copper strip and really it's a stupid way to attack the problem.


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## nj_m715 (Oct 31, 2008)

There's a yahoo group that's all about turning chest freezers into fridges. Most of them use a beer brewing t-stat to control the temp, but there are other options. They're into other energy saving things like super insulating the unit and using root cellars. 
RefrigeratorAlternatives : RefrigeratorAlternatives


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## townparkradio (Mar 30, 2010)

Well, as they say, everything you think of has been thought of before... but that's no reason for me to give up innovating. Thank you for the link, it gave me a lot of information.


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## Tirediron (Jul 12, 2010)

The chest freezer to fridge is a very good idea, but watch out for super insulating, the condensercore is along the outside of the freezer's metal enclosure and MUST get rid of heat , refridgeration is all heat pumping and the heat pumped from the area that is cooled needs to be exchanged with "room air" (I didn't watch the videos in the link maybe they mentioned this already


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## gypsysue (Mar 27, 2010)

We read somewhere a couple years ago that you shouldn't put insulation on a fridge, but of course I can't remember why it said not to! 

TPR, that's actually a brilliant idea, your freezer-to-fridge plan. I'd have never thought of it! Your in-laws are lucky to have a smart and helpful son-in-law like you!


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## ZoomZoom (Dec 18, 2009)

All I can do is pile on and say it's done regularly by home brewers. I have a couple friends that did exactly that. IIRC, the conversion part is about $20 and takes 15 minutes to install it.


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## Tirediron (Jul 12, 2010)

Didn't I just answer why not to add insulation? , the condenser needs to get rid of heat, if you insulate the outside of a freezer the heat removed from the interior (the now cold part) has no where to go and the freezer becomes LESS efficient because the compressor runs for more time trying to cool :scratch


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## ZoomZoom (Dec 18, 2009)

Tirediron said:


> Didn't I just answer why not to add insulation? , the condenser needs to get rid of heat, if you insulate the outside of a freezer the heat removed from the interior (the now cold part) has no where to go and the freezer becomes LESS efficient because the compressor runs for more time trying to cool :scratch


Who said to add insulation? Every post I quickly re-read agreed with you.


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## nj_m715 (Oct 31, 2008)

I said it, but I thought it goes without saying (guess I was wrong) that you do not insulate the condenser coil or the compressor. You insulate the rest of the unit to keep the cool air in. Some guys used foam boards or even just an old blanket. 

Sue, All units come from the factory with some insulation, you just add a little more.

Cleaning the coil to allow for max heat transfer helps a lot too. When the last time you guys pulled out your fridge to the back and bottom? Make sure your door seal is in good shape.


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## gypsysue (Mar 27, 2010)

Yeah, I knew not to insulate around the condensor. Our fridge is a 2-year old frost-free, and it has a smooth back, with the motor "stuff" at the bottom, underneath, open to the back. We keep the motor area clean.

As for insulating the side walls and top...I never could figure out why that would be a problem. I guess it wouldn't be. We have plenty of that 1" styrofoam sheet insulation leftover from another project. Might give it a try.


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## townparkradio (Mar 30, 2010)

Misread. Never mind.


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## gypsysue (Mar 27, 2010)

townparkradio said:


> Misread. Never mind.


Sorry, TPR, I guess we kind of side-tracked your thread.

I hope you can find a way to make a thermostat that would do that -- shut down at the right temperature. Surely someone on here knows something about this? Where's JeepHammer when we need him, he seems to be the go-to guy for a lot of things! Smart guy.

Anyway, I thought this was a good idea.


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## Emerald (Jun 14, 2010)

I've been dreaming of redoing my kitchen for years so I do read many things about remodeling and watching all those kitchen redo shows and they now have small fridges that are just drawers that can be built into your cabinets. They are supposed to be very energy efficient not only due to no loss of cold air falling to the floor-and by the fact that most are used for sodas and stuff that your kids tend to just open and close that big fridge for anyways. So it keeps the big upright fridge closed more.

But if you had small fridge needs and lived off the grid then having maybe just two or maybe three of these small drawer fridges might be the way to go.. But last I looked they were EXPENSIVE!:gaah:


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## gypsysue (Mar 27, 2010)

When we bought the electric fridge we use with our off-grid solar panel array, we went to Home Depot and looked at the watt rating on every fridge. It was interesting to us to discover that a 10-cf frost-free fridge/freezer uses about the same amount of electricity as the smaller "college" fridges. Over that size the watt draw was much higher. The big fridges were way up there.

We bought the 10-cf one and have used it with our solar panels for 3 years. Long cloudy spells in winter (short daylight hours) are a strain on the solar power, but we simply turn it off if the weather is cold enough anyway (it's on a covered porch on the north side of our cabin).

I wonder what the watt rating is on those drawer-type fridges? I'll have to search that! Thanks, Emerald, for the information. It's great to hear about new products.


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## Tirediron (Jul 12, 2010)

bczoom, I misread you answer, thought you said pile it (insulation on ) 
And I was reffering to just freezers when adding insulation, because a lot of them have condenser plates next to the skin on all 4 sides.
The chest freezer to fridge conversion is done often and can be super efficient,but maybe not all that conveinient 

A stand up fridge could be inproved by adding an internal half door in the bottom to keep the cold from cascading out every time the door is opened
you would just have to keep the most used stuff on the top shelves,and watch for freezing on the bottom shelves :flower:


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## nj_m715 (Oct 31, 2008)

Speaking of the frost free models, you can disable the feature and gain a lot of savings. In order to be frost free they have a little heater inside to switch on every now and then to melt the ice. The heater takes energy to run and forces the fridge to work that much harder. Being frost free is more convenient but it comes at a price. 
I plan on unplugging my heater next time I clean out the fridge. Once or twice a year I like to use up as much of the food and drink in the fridge as possible. I put what's left in my little electric coleman cooler and scrub down the fridge inside and out. My cleaning should be enough time for any frost to melt. When I was a kid my parents had a deep freezer that needed to be defrosted once a year. I don't see why it wouldn't for me.

This thread's not really high jacked. We're talking about saving electric and I pointed him to the right place for the conversion parts in the first reply.


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## JeepHammer (Oct 10, 2008)

I did 2 things to make my freezer more efficient.

1. MORE INSULATION!
Can't go wrong with more insulation!
Keeping the cold IN, and the heat OUT is the objective...
Insulation helps with that.

2. Vented the compressor heat outside.
Since the freezer sets on the back porch, and the other one is in the shop,
I vented the compressor away from the freezer so it doesn't have to fight it's own heat.

If your freezer is in your home, you probably won't have that option unless you install ducting to take the compressor heat out of the building.

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*If you shut off the power to the freezer at 32°F. The internal temp WILL NOT be maintained, and you WILL get freezer burn or ruined supplies.
Virtually ALL freezers will turn themselves off when internal temps reach that point. No need for external thermometers.
If you can't maintain at LEAST -10°F. then the 'Freezing' isn't complete, and meat in particular will spoil right there in the freezer.*

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What WILL save you money in the long run is to install OVERSIZE wire to the unit, 
At least 10Ga. for a 110 volt unit,
And at least 8Ga. for a 220 volt unit.
Freezers should have their OWN breakers and 'Emergency' lines if you have a generator or produce your own back up or primary power!

Cut the plugs off and HARD WIRE the units to the service line.
Plugs create a LOT of resistance, resistance (Small wire, faulty or too small of contacts in the plugs) will waste electrical current in the form of heat.

Most people argue with me on this until I whip out the infrared heat gun and show them the 'Glow' from the excessive heat build up...
Then I compare heat over ambient to the losses to produce that heat,
Then figure in the energy losses @ the cost of the electricity...

Pretty soon they are wanting to up-size the wire and hard wire to get rid of those losses (and potential fire staring points!) and that's ALWAYS a good thing!
Heating up wire/plugs doesn't NOTHING but waste your electricity, and since you don't move the unit (except for cleaning) for YEARS, there is no reason NOT to do it!

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Making sure your unit is CLEANED at least 4 times a year (Dust bunnies, lint accumulation, general crud on the external coils) will reduce efficiency by up to 40% in less than a year.
Make sure you keep the crud blown out of them, and keep the coils on the back/underside CLEAN with soap and water.

Generally, small freezers don't have large enough coils to be really efficient, so if you are looking,
Look for 'External' compressor units,
Like your home A/C unit,
Where the compressor heat and hot coils are outside the home,
Then you don't have the heat in the home to start with,
And the coils are MUCH easier to clean that way...

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If you know a HVAC guy, ask about moving the compressor outside on the 'Home Consumer' units...
(he'll probably look at you like you are retarded at first, but once he figures the heat generation in the home, he'll figure it out pretty quick)
This will save you a lot of money trying to cool the home from the heat produced by the fridge/freezer, and make your system more efficient at the same time.

Picking up EXTERNAL compressors is always a good thing, and you will be surprised how cheap they will go for when the building is being remodeled or replaced with bigger building!
You CAN run your fridge/freezer off a 'Split' or 'External' compressor just fine,
It just takes some plumbing and wiring for sensors, and there really isn't much to it...
Makes that favorite freezer useful again when the compressor goes out and costs more to replace that little, inefficient compressor than the fridge/freezer is worth...
Hook it up to a split system, and you are back in business and half the cost!
And you can run MORE THAN ONE appliance off a compressor, that's not an issue...

Split systems also give you the option to add a diesel, gasoline or propane/natural gas 'Hot Box' to power up the house with a generator and use the internal combustion engine to turn the refrigerant pump for cooling without taxing your electrical reserves in an emergency situation.

Big truck 'Hot Boxes' or 'APU' units work GREAT for this, and usually come with the valving for the auxiliary A/C or Refrigeration unit and hot water, electricity all built into one unit...
Since they are used in EVERY big truck salvage yard,
And they are EVERYWHERE used/rebuild on the internet,
They are a VERY good choice for 'Emergency' power, refrigeration, hot water.
(Water cooled units only will do hot water)

Remember, every internal combustion engine WASTES at least 85% of it's fuel making HEAT, so no reason NOT to harness that for hot water while you are at it!

Might as well use MORE of the fuel you are putting into your backup system and getting something for it!

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I'm looking into using that waste heat from the 'Hot' coils in my refrigeration units to preheat water in my home under normal conditions.
Every refrigeration unit produces a LOT of heat, and that heat is shed to atmosphere, no matter if it's in doors or outdoors...

'Wet' heat exchanger (inter-cooler) will make the compressor MUCH more economical, plus I salvage the heat produced for preheating water for the system.
(Closed loop)

Outdoor compressor 'Split Systems' are used in all commercial applications,
From convenience stores to factories, and they are MUCH more economical to operate,
But they are also more expensive when you purchase/install.
Since the fans, coils, ect. can be MUCH larger, they are more efficient than the little units the stick UNDER the 'Consumer' units where it's all packaged up in a very compact space.

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If you still want an 'Industrial' thermostat to shut things down,
You are looking for the heavy duty ones...
You can get the ones from 'China' but they never live,
You are looking at around $65 to $120 for a good one,
Honeywell and White-Rodgers are the ones I use most in the shop, ect.

This is what they look like, and there are two kinds.
The 'Room' type that has the capillary tube sticking out the top for ambient room temp,
And the kind with 'Bulb' at the end of a capillary tube for 'Remote' temp control, so you can stick the probe in the freezer or what ever.



















......................

Probe type,



















*I DO NOT recommend this for a Freezer since this will keep the unit from reaching the -10°F. or colder needed for keeping things SOLIDLY frozen...*


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## mosquitomountainman (Jan 25, 2010)

Tirediron said:


> "... And I was reffering to just freezers when adding insulation, because a lot of them have condenser plates next to the skin on all 4 sides. ..."


A lot of the newer refrigerators have the condensor coils next to the outer skin also. In those cases adding insuation to the outside of the fridge will do more harm than good.


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## gypsysue (Mar 27, 2010)

Thanks, Jeep, for all the info. Great information.


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## JeepHammer (Oct 10, 2008)

Yes, it depends on the model and design,
If you see the coils on the back, insulation BEHIND them, between coils and fridge is good,
but if you don't have exposed coils, then don't insulate the back,
Top and sides are usually fine.

If you can bend those condensation coils out where they get open air without cracking the lines, that's always a good thing.
We have about 2 feet behind our fridge, so I bent them out about 20 degrees or so and braced them away from the extra insulation, and that seemed to help also.
A low consumption fan back there that kicked on with the compressor would add efficiency, but I haven't got around to that yet...

When we went off grid, we went for a super efficient model ($$$!).
Standard 'Large' outside, but smaller inside with 'Zones'.
Smaller inside means more insulation space,
And we looked for one with coils exposed on the back.
Many of the new ones have the coils on the bottom, and heat rises, so that's not real good.

Some blue board insulation between coils and cabinet didn't cost but a few bucks, and with the temp gun, the cabinet stays room temp instead of being cool, so it's got a bunch of GOOD insulation around the internal box.
Doesn't run very often, but we make a point of keeping the door CLOSED until we figure out what we want...

We keep the freezer on the back porch...
Porches are less tax dollars than internal space,
The freezer doesn't exhaust heat into the house (Which wouldn't be bad if you lived where it was Cold more than too warm)
So we save on the A/C energy in the summer.

Next time I do a fridge, it's going to be a split system with compressor in the utility room or outside.
I'm fiddling with recovering that heat from the condensation coils, but don't have anything off the drawing board yet...
I'm trying to figure out how to plumb it into the preheat tank, but I'm not a big HVAC guy...
I'll probably steal the design from an up and running system...
I know a good idea when I steal it!


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## mosquitomountainman (Jan 25, 2010)

JeepHammer said:


> Yes, it depends on the model and design,
> If you see the coils on the back, insulation BEHIND them, between coils and fridge is good,
> but if you don't have exposed coils, then don't insulate the back,
> Top and sides are usually fine.


Not trying to be contentious here but ours has coils along the side under the outer skin. The side gets hot when the fridge is working hard. Got out the owner's manual and it said no adding insulation on the outside for that reason. It was a new one on me.


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## JeepHammer (Oct 10, 2008)

Like I said, depends on model and design...
If they told you NOT to add insulation to it, then I'd go with what they tell you!

I looked for some very specific things when we got ours...
(I know just enough to be dangerous!)

Condenser exposed in the back was one of the things I was looking for.
I had to remove a sheet metal 'Bump' shield to get at them, but it was 'Doable' by taking out 4 screws so we could bend the condenser out into open air and add the insulation...

Nice piece of stainless sheet metal for projects!

I don't pretend to be the last word in fridge or freezer design,
I know just enough to see things I DON'T LIKE on most...
Like condenser under the fridge where the heat rises right up into the cooling compartment,
Compressor connection lines made of aluminum or steel so you can't service the compressor,
Lines without suction or fill line fittings so the system can't be serviced when it eventually leaks down (and they ALL leak down over time...),

I never paid any attention to the 'Frost Free' heater until this thread, but that guy has a point...
No reason to run a heater in your freezer!

I know WHY they do it, I know (in theory) how it works, but it seems wasteful to me and I'll have to take a second look at my fridge now!
(Oh NO! The little woman isn't going to like me 'Tinkering' with her shiny fridge!)

Wonder how much energy that defroster heater uses, and how much energy the compressor uses to cool things back down after the defrost cycle?

I noticed a high end house being built down the road has a vent behind the fridge space...
Wonder if that was spec'ed by the fridge manufacturer or the home builder?
Good idea either way to evac the heat and give some air flow to the condenser/compressor housing...

Another idea stolen! 
Don't know if it's a 'Good' one or not, but I'm looking into it anyway!


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## townparkradio (Mar 30, 2010)

gypsysue said:


> Sorry, TPR, I guess we kind of side-tracked your thread.
> 
> I hope you can find a way to make a thermostat that would do that -- shut down at the right temperature. Surely someone on here knows something about this? Where's JeepHammer when we need him, he seems to be the go-to guy for a lot of things! Smart guy.
> 
> Anyway, I thought this was a good idea.


no I meant I misread something someone else said, and then tried to delete it and.. there's no delete post function!


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## nj_m715 (Oct 31, 2008)

Venting to the outside is great during the summer, you're thinking of building something like that try to make vent inside during the winter and outside during the summer. The coils can give your kitchen some "free" heat in the cold months. 

I thought about setting up something to seal the back of fridge to the wall and add set of vents to move the waste heat to the outside during the summer. My fridge is in a corner so I only need to seal one side and the top. I want to use something like wooden door or window trim with stick on foam to make the seal. A 8 or 10" through the wall kitchen exhaust fan mounted near the top of the fridge and wired to kick on when the compressor runs will draw cool are under the unit and cross the coils from the bottom to the top where it will remove the heat from the coils and be drawn out through the fan. 
I rarely use my A/C so I don't mind drawing the room air from the floor. If you use your air conditioner a lot then I would completely seal the fridge to the wall and floor and add an extra vent pipe under the front of the fridge. In my house I could simple add an old fashion floor grate and draw air from the basement or get fancy and add a 8-10" duct to the vent to draw in outside air. 
It should be relatively cheap to set up, easy to swap from summer to winter mode and be "pretty" enough to keep the wife happy. But until I recover from my back surgery it's just a pipe dream. 

I might start by installing the fan and building a test containment seal by simply using 1-2 inch foam pipe insulation to seal the fridge to the wall. If it looks like it's working I can put the extra effort into building a pretty seal from trim. 

Hopefully you guys can get my idea without a drawing or pic. Sometimes it hard to verbalize the picture in your head. If not ask questions and I'll try to explain better. If you know how the new two pipe heaters work I'm thinking of the same idea. Draw in fresh "combustion" air from outside and vent the hot "exhaust" air outside.


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## GetPreparedStuff (Dec 16, 2009)

I found an old article I had read that describes how to convert a chest freezer to a fridge and uses only 0.1 kWh per day.
Chest fridge


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## questor (Nov 9, 2008)

I don't know if it is in this thread, 
BUT you can also scavenge the heat from the coil to preheat your hot water tank or just use it to heat the room.
I've found a 12 volt computer fan works just right for my set up


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## OldFashionedMama (Jun 18, 2009)

Instead of converting a chest freezer, what about building your own alternative power source for a fridge? My dad just told me about a homemade wind generator that he made out of a car alternator, battery, and pvc for the blades. He says at full speed this little thing can generate 800 watts of electricity, and only cost about $140 to put together. I don't know how much you'd need to run a fridge, but perhaps if you had a couple of these machines you could run one?


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## mosquitomountainman (Jan 25, 2010)

OldFashionedMama said:


> Instead of converting a chest freezer, what about building your own alternative power source for a fridge? My dad just told me about a homemade wind generator that he made out of a car alternator, battery, and pvc for the blades. He says at full speed this little thing can generate 800 watts of electricity, and only cost about $140 to put together. I don't know how much you'd need to run a fridge, but perhaps if you had a couple of these machines you could run one?


Can you get us pictures and plans of what he did and how he did it?


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## OldFashionedMama (Jun 18, 2009)

mosquitomountainman said:


> Can you get us pictures and plans of what he did and how he did it?


I will try. He's supposed to call me back because I'm expecting a delivery of firewood from my brother-in-law and I need to borrow his tiller, figured he could just send it up with him. I know it's taken him all summer to build, but I don't know if that's because it's difficult or because he works a lot.


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## The_Blob (Dec 24, 2008)

OldFashionedMama said:


> Instead of converting a chest freezer, what about building your own alternative power source for a fridge? My dad just told me about a homemade wind generator that he made out of a car alternator, battery, and pvc for the blades. He says at full speed this little thing can generate 800 watts of electricity, and only cost about $140 to put together. I don't know how much you'd need to run a fridge, but perhaps if you had a couple of these machines you could run one?


:scratch

Seems to me that the biggest problem with using car alternators for wind power is that they are designed to rotate at too high a speed to be practical in wind power applications without significant modifications. Even a small, seemingly fast windmill might do most of its work at 500~600 rpm, not nearly fast enough for a car or truck alternator. This means that gearing up with pulleys or other methods is needed, so lots of power is lost to friction--a big problem with wind or water power, but not a problem with a gasoline engine...  :ignore:

A complete Delco Si-12 Pm Alternator weighs like 10 pounds, haven't seen one on ebay, but they do have other heavyduty new, used, and refurbished ones


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## nj_m715 (Oct 31, 2008)

it's been done. Go search youtube. Ebay sells permanent magnet alternators which are better for homemade wind gen. They say the windmill should be 20-30 ft above any near by structure and many areas just don't get enough wind. Of course the issue of too much wind also. It needs a "brake" or a load to take the extra power and slow down it down enough so it break apart.

If you really want to take your fridge off-grid look into these:
Crosley IcyBall

I love the home made one at the bottom of the page. It's one of my projects on the back burner.


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## Tirediron (Jul 12, 2010)

GetPreparedStuff said:


> I found an old article I had read that describes how to convert a chest freezer to a fridge and uses only 0.1 kWh per day.
> Chest fridge


The conscept is definately on the money but the thermostat is enough to scare most people away, as mentioned in the second reply off the shelf thermostats are available, or just replace the freezer stat with a fridge stat 
this conversion would be well suited to non grid power


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## labotomi (Feb 14, 2010)

nj_m715 said:


> It needs a "brake" or a load to take the extra power and slow down it down enough so it break apart.


You can find overvoltage relays that will close some contacts and open others upon exceeding a set voltage level. Just connect the normally open contacts in parallel to the batteries through a heavy resistor bank and the current will cause "motoring" of the generator. The resistor bank should be sized to handle full generator output current, but it would be good to have a variable resistor and be able to tweak the resistance and thus the current levels to protect the resistors while allowing adequate braking of the windmill.

The motoring effect will produce torque in the opposite direction to what the windmill is turning and in effect cause a "braking" effect on the windmill.

You'll have to run the battery charging leads through the normally closed contacts on the relay also. This will prevent the battery from discharging through the resistor bank when in an overvoltage condition.

Once the windmill slows and voltage comes down the contacts will open and again start powering the batteries.

This will direct the power to the batteries when voltage is not excessive and through the resistor bank when the voltage is higher.

Just make sure your resistor bank can handle the current and expected wattage that you expect the generator to produce. Also make sure it's ventilated sufficiently to remove the heat.

We have these installed on our variable frequency drives that are powered by a DC inverter. In the event that a motor is oversped (as during slowing) the DC bus voltage can go too high and thus the excess power is diverted to keep voltage levels with in tolerable limits. I don't think you'd want to purchase ones like we use as they are rated for much higher power than you'd get from a windmill generator and the price reflects that.


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