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Refrigerator-low draw options

Bluedog225

Bluedog225

Solar Wizard
Joined
Nov 18, 2019
Messages
4,064
Location
Texas
Based on this thread,

diysolarforum.com

Microwave for a 1200 watt inverter?

Hey guys, a while ago I built a 1200-watt system for camping. I would like to have a small microwave but I bought a 700 watt one from Walmart and it freakin pulled 1400 watts and tripped the inverter. And my bms is 1200 watts so a bigger inverter doesn't help. Anyone using a small microwave that...
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I’m going to order the recommended microwave.

And I ordered the victron 12/1200.

Does anyone have a good suggestion for a “best in class” fridge? Or a ”better” microwave?

Is there such a thing as an “inverter“ fridge?

Thanks

F2600199-18F1-4E4B-A841-E14897E08959.jpeg

E448A151-9A59-434B-9A29-CB295935C3B2.jpeg
 
There are LG Inverter fridges that don't draw too much, we have a 20 cu ft side by side bottom drawer LG Inverter fridge that draws something like 450 Kwhrs/yr. It typically draws an average of about 30 to 40 watts, has no significant surge and appears to adjust run speed to current need for cooling.
 
The defrost cycle and the heating element near the bottom of a freezer door consume allot. I'm using an upright fridge or freezer(convertable) that does not have a defrost heater or blower fan. Down side is, moisture on the inner walls all the time. It is a Vissani from homedepot, about the size of a large RV fridge.

www.homedepot.com

Vissani 7 cu. ft. Convertible Upright Freezer/Refrigerator in Stainless Steel Look MDUFC7SS - The Home Depot

Bring freshness to your life with the VISSANI 7 cu. ft. upright freezer. The removable shelf will help you to manage your storage flexibly. The convertible function gives you additional choice in managing
www.homedepot.com
 
I have this one. bet I cold start it of my 400w inverter. Only thing I don’t like is every 24 hours it does a 200w defrost cycle. I wish they made an inverter deep freeze also but they don’t.

20 cu. ft. Top Freezer Refrigerator - LTCS20020W | LG USA

Discover the 20 cu. ft. Top Freezer Refrigerator that features Reversible Door and Premium LED Refrigerator Lights. Shop LTCS20020W from LG USA.
www.lg.com www.lg.com
 
Microwave is about .9 power factor so about 10% additional apparent watts may be needed. So that 980 watts consumed need 1100 watts available. Good but very close.

Consider a Panasonic "inverter" microwave that reduces power at lower settings instead of cycling the magnetron at full power. This one goes as low as 670 watts on power level 3. If utility or generator power is available then it can use full power.

. Skip to 4:00 time

Sorry, no help on the fridge. Mine is propane and 250 mA.
 
I’ve not done it. But it seems like it would be an easy hack to cut out the defrost circuit. Fridges and freezers are pretty modular, plug and play components.
 
rodrick said:
What did you not like about a chest refrigerator
Click to expand...
Its hard to get food in or out. Things end up sideways and on top of each other. Its like one shelf but you have to put stuff on top of each other since there isn't much space. One or two people could make it work. A system of stacking tubs could help. Most of the items end up collecting moisture on the outer surface. Water will collect on the bottom since most freezers don't have a tapered drain at the lowest point. Our drain was about .5 inches up from the bottom.

Our current fridge has moisture on the walls since its a convertible upright and the walls provide the cold surface. We have not had issues with moisture on the containers. I'm not sure why there is a difference.
 
Bluedog225 said:
I’ve not done it. But it seems like it would be an easy hack to cut out the defrost circuit. Fridges and freezers are pretty modular, plug and play components.
Click to expand...

Did just that years ago.

The coils frosted over and it wound up using MORE power in the long run because the airflow through them became restricted.

Fridges with auto-defrost are engineered to have it. If you disable it, things become less than optimal.
 
I learn a lot from these threads


Inverter micrwave
I would have never even thought of that
 
Last edited:
FWIW: ~1.5 kWh/day for a standard fridge that anyone can buy at thier nearest appliance seller is not a bad deal at all. I've played around with the "total system cost per cubic ft" a few times and the standard Energy Star fridge is often the winner for most applications.
 
I was looking real hard at this fridge at work
( we have a lot of fridges and lunchrooms so we buy a lot of appliances…. Always something new shows up )

It’s just a cheap unit with a small compressor small size and few basic controls
What stood out for me was no indication of a timer for frost free functions
Easy to buy r600a
No internal fans

I thought it might be a good candidate for 12 volt conversation

After reading this thread I’m not so sure there’s an advantage to it

B3606869-E901-43EC-8A1F-4A91A0FC0ABC.jpeg3368A56E-5E68-499C-9598-5C0A8DB73D6C.jpeg
 
Some technical as built details

Locked rotor currrent is low 6 amps so it’s easy to start as built
6 cc compressor volume

The Danfoss bd50 by the book looks a little small for this
The bd80 is 3 cm compressor

Advantage with inverter is you can set compressor speed
I could adjust it to run 3500 rpm and match the cooling power of the ac unit
I can set it to 2000 rpm and tune it to the unit to run at a 50 percent duty cycle for peak efficiency

Bd80f is rated for the new refrigerant
Technical details on it lead me to think it might be more efficient that the old non flammable types

Flammable however
Now we are back to a refrigeration system that can cause a fire same reason I have turned my nose up to absorption fridges

Thought experiment
Is it worth the trouble to build a fridge
With a really well insulated box myself and fit a chill plate and compressor system all by myself
 
Last edited:
Bluedog225 said:
I’ve not done it. But it seems like it would be an easy hack to cut out the defrost circuit. Fridges and freezers are pretty modular, plug and play components.
Click to expand...
If its a classic fridge design,
DPC said:
I was looking real hard at this fridge at work
( we have a lot of fridges and lunchrooms so we buy a lot of appliances…. Always something new shows up )

It’s just a cheap unit with a small compressor small size and few basic controls
What stood out for me was no indication of a timer for frost free functions
Easy to buy r600a
No internal fans

I thought it might be a good candidate for 12 volt conversation

After reading this thread I’m not so sure there’s an advantage to it

View attachment 133748View attachment 133749
Click to expand...
R600a is nice. Efficient and moves oil well.
 
Before you go out and get the lowest draw microwave or refrigerator you might look to see if it is something you want to live with first. Case in point, I recently replaced my 12 year old microwave 1000w with a new 900w one. Two things about it that jumped out for me. It takes longer to heat things up and it has less interior capacity to put food in. It may be easier to start with a smaller inverter but since it runs longer the overall energy use is the same. After a couple of weeks of using it I am thinking of going out and buying a 1K-1.1Kw to use instead.

Same thing applies to refrigerators I would expect. You can get a smaller, non frost free refrigerator/freezer and it will require less power to operate. However you also will find that it might not be ideal for how you want to use a refrigerator.

It might be better to buy the inverter (and associated battery, charger setup) that will run the appliance rather than buy the appliance your inverter will run.
 
Mattb4 said:
Before you go out and get the lowest draw microwave or refrigerator you might look to see if it is something you want to live with first.
Click to expand...
Mattb4 said:
You can get a smaller, non frost free refrigerator/freezer and it will require less power to operate. However you also will find that it might not be ideal for how you want to use a refrigerator
Click to expand...
OP: what is your budget?

I ask because… my latest ftidge is a 7.7? cubic feet top freezer Element. No defrost. ~80W running. It has much thicker insulation than the prior magic chef ~5.x cubic foot that ran at 60W. I believe the bigger/new one uses the same or slightly less Wh than the smaller one in 24hours because it runs less often. And I paid $215 brand new at walmartha.

The DC fridges and schmancy 120V low W units cost $700 to over $2000. A couple extra solar panels and maybe a tad more battery capacity and you’ll have money leftover. I can’t see the spend on the schmancy fridges myself. If one can afford it or money is no object do what you want to- no criticism there- but eeking that last screaming watt out with solar isn’t always as productive and satisfying as having what works and not spending a fortune on it. Imho- ymmv
 
My wife was out of town when the microwave in the house died. I went out to the local big box store and bought one just like it. Big mistake. My wife doesn't like the new one and I've been paying for that for years now. I just can't win.
banghead.gif
 
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