I have a beginner's questions about fridges. I downloaded both the planning worksheet and the reference guide for wattages. Both are extremely helpful so kudos to the folks that put them up. My plan is a 24x32 (or close to that) cabin off-grid and I had most of the figures down. Concerning batteries I was sitting at a minimum of 3,543 watt hours and 295 amp hours. According to the reference guide an average fridge/freezer grabs 700 running watts and 2200 surge watts. When I inputted those figures along with running it 24 hours per day my watt hours jumped to 45,024 and amp hours increased to 3,752. So adding the fridge took me from a couple of 200+ amp hour batteries to a bank of 18 or better! That's if I'm doing the math right and since I'm new to this there's every possibility I'm not. As a matter of fact I really hope I'm not. So, advice? And thanks in advance.
Refrigerators
- Thread starter dmizesr
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Just be aware that a refrigerator has a duty cycle. The compressor might run 30 minutes out of an hour (this is a ball park estimate) so you maybe overestimating by quite a bit. A Kill-a-Watt meter would be the best way to know for sure with any specific fridge.
You might consider a propane refrigerator or a small high-efficiency electric model. Probably a lot cheaper than all those extra batteries.
You might consider a propane refrigerator or a small high-efficiency electric model. Probably a lot cheaper than all those extra batteries.
I have no math. As I said, I used the estimator spreadsheet and filled in the blanks. My initial mistake was in assuming when it asked for hours per day that for a fridge it would be 24 since I want it on all the time. I have since learned the concept of duty cycle. For now a meter would be useless since I doubt I'll have my current fridge when I build. I'll definitely buy something newer and more efficient.
That's helpful. I had no idea about duty cycle. I won't have the same fridge when I build but I will definitely be shopping around for the most efficient thing I can buy. Thanks.
MisterSandals
Participation Medalist
My experience is that my fridge and freezer each run about 20 min per hour (33% duty cycle).
Your numbers look to be a lot more than my 27cuft GE Energystar refrigerator/freezer (2 ice makers, water dispenser, door electronic display). I recall 125W when running and about 25W idling. This comes to (125 x .33) + (25 x .66) = 41.25W + 16.5W = 57.75W average
Fun with numbers: 57.75W x 24h = 1386Wh daily
...x 365h/y = 505890Wh per year
(i cut and pasted this from a previous post a while back, i think the numbers are good)
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Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Do careful shopping and pay close attention to the specs & ratings. I have an EnergyStar Fridge (Danby Eco Model) that only uses 524kWh for a whole year. EnergyStar got partially gutted by the former US Administration but many companies are adhering to the specs and sticking to it.
One thing is to avoid having extra's in the fridge like a Water Cooler/ Ice Dispenser, while convenient as all heck, they hit the efficiency rating Big Time. If possible get a fridge that has the freezer in the bottom (IF it has a freezer) as these are more efficient. Most efficient are dedicated Fridges & Dedicated Freezers but this is not usually North American Thinking.
One thing is to avoid having extra's in the fridge like a Water Cooler/ Ice Dispenser, while convenient as all heck, they hit the efficiency rating Big Time. If possible get a fridge that has the freezer in the bottom (IF it has a freezer) as these are more efficient. Most efficient are dedicated Fridges & Dedicated Freezers but this is not usually North American Thinking.
The 700W is not the running wattage, most likely that is the defrost cycle maximum which may occur for a short duration when required, I logged my refrigerator over a month, which includes defrost below are the results. Medium sized, bottom freezer, inverter type, ambient temperatures 30-37°C.
Short_Shot
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My big French door bottom freezer with ice cube maker up top pulls 1.2 kwh in a 24 hour period.
Probably a bit more on average if defrost didn't run that day but I need to move my microwave to a different outlet or use a short extension cord to test longer term. Stupid killawatt blocks the other outlet.
Buy yourself a killawatt meter. They're cheap.
Short_Shot
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What hardware and software did you use for this?
Just a plug in device like a Kill a Watt device, with some enhancements, it's a Zhurui PR 10, a Google search will lead to details, available in various voltage and plug types, around $50.
Hedges
I See Electromagnetic Fields!
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You think bottom freezer was more efficient? I thought top freezer was supposed to be.
Top freezer should also keep refrigerated food at a reasonable temperature during power outages by continuing to spill cold air into fridge.
Of course, those with fan cooled condenser are probably more efficient than older models which worked by convection. But you do have to clean the cat hair off periodically.
Plecoptera
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I have a Norcold 3 fuel reefer in a travel trailer that has a nominal run rate of 140W. The on-board wiring and battery charge/discharge rates for AGM ended up making trying to power it with DC/Solar frustrating. Soooo, I bought a small 35qt high efficiency freezer that consumes 70W, loaded it with blue-ice type cubes, and use it to freeze the cubes which I then put in my Norcold 3 fuel icebox.
I know my problem is not your problem, but my point is there is maybe more than one way to skin this cat.
I know my problem is not your problem, but my point is there is maybe more than one way to skin this cat.
Short_Shot
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Technology connections did a video on it.
I don't recall the verdict, but I think you're correct that freezer on top is more efficient but don't quote me there.
My shop/apartment is off grid. Completely wired to code that I back feed with generators.
I cycle my small fridge and freezer off manually. Frozen water bottles in the freezer and I can get about 8 hours of no power and it’s been hot here. Fridge doesn’t keep cold as well.
I turn the freezer on for about 2 hours in the morning after being off for 8 and then an hour or so 2 to 3 times a day.
I cycle my small fridge and freezer off manually. Frozen water bottles in the freezer and I can get about 8 hours of no power and it’s been hot here. Fridge doesn’t keep cold as well.
I turn the freezer on for about 2 hours in the morning after being off for 8 and then an hour or so 2 to 3 times a day.
Guess that depends on how many times a day the freezer is opened, the freezer is a drawer type so less chilled air falls out, energy guides generally do not open the doors for their testing, but to be honest I bought the particular model because it was discounted to make way for the all new model.
The small freezer route was what I did at the beginning but found it was like living out of a backpack, it always seemed like what was needed was at the bottom, the refrigerator I have draws between 30 & 63W without surge and a lot more convenient.
12VoltInstalls
life passes by too quickly to not live in freedom
I have a 1/2-size fridge/freezer that is currently running and inverter is showing 80W but usually reads about 60W.
There are inexpensive ~12cf fridges (2.3 times my size) that run at 60-80W if you can get by with little fridges.
Anyway when I switched from propane to this 5.3cf electric compressor fridge I was in the midst of experimenting with 2S2P 100W panels and was going to connect my other 300W but I’ve been all summer on 400W and 12.2V is the lowest I’ve seen in the AM.
My point is that if you can get by with less space there are <$300 options that are watt misers. (There’s also much bigger options $2000+ in the low watt realm but that isn’t the point.) I’m not recommending 400W but I apparently made it work.
There are inexpensive ~12cf fridges (2.3 times my size) that run at 60-80W if you can get by with little fridges.
Anyway when I switched from propane to this 5.3cf electric compressor fridge I was in the midst of experimenting with 2S2P 100W panels and was going to connect my other 300W but I’ve been all summer on 400W and 12.2V is the lowest I’ve seen in the AM.
My point is that if you can get by with less space there are <$300 options that are watt misers. (There’s also much bigger options $2000+ in the low watt realm but that isn’t the point.) I’m not recommending 400W but I apparently made it work.
I think the top freezer is more power friendly
I think the slide out draws are still open all the way around any way .
I don’t like crawling in the bottom draw for food.
all the fringe Freezers use around 125 watts running but some run longer .
Mine use about 1100/1200 watts
The size of the cabin dosent really matter , you need a frig lites tv radio water
it seams to me that 3500 to 4000 watts will work for a cabin .
A couple of 200 watt battery’s won’t really cut it
I used 8 215 ah cheep golf cart battery’s 100$ and I use about 18% of my battery over night .
6 300 watt panels will keep you charged up for 9 month of the year .
Now I have 16 battery’s and 4500 watts of solar soon to be doubled for winter Production .
I would go with a 48 volt system to start with .
I think the slide out draws are still open all the way around any way .
I don’t like crawling in the bottom draw for food.
all the fringe Freezers use around 125 watts running but some run longer .
Mine use about 1100/1200 watts
The size of the cabin dosent really matter , you need a frig lites tv radio water
it seams to me that 3500 to 4000 watts will work for a cabin .
A couple of 200 watt battery’s won’t really cut it
I used 8 215 ah cheep golf cart battery’s 100$ and I use about 18% of my battery over night .
6 300 watt panels will keep you charged up for 9 month of the year .
Now I have 16 battery’s and 4500 watts of solar soon to be doubled for winter Production .
I would go with a 48 volt system to start with .
