chest freezer kwh in full day

just starting

Does any one have real results on a small 4-7 cf chest freezer where I live it doesn't get above 85°f we have snow from nov to July usually.

Photowhit

New freezers tend to be pretty good, use the provided energy rating. You might have to do the math to figure out the per day usage, but it's simple stuff. Most use less than 1KWh and as you have given a temperature range, I will assume the freezer will be subject to the temperatures, hopefully not the snow!

I can't recall the exact problem, but some freezers don't work properly when they are subjected to ambient temperatures below freezing.  I suspect frost free freezers have issues with melting the ice from the coils...

BB.

I believe the "typical" problem if running in too cold an environment is with Refrigerator/Freezer combination units (with a single compressor/evaporator). The freezer is "over cooled" until the refrigerator reaches its set point. If your (garage/room) is less than ~40F, then the refrigerator thermostat never turns on, and therefore the freezer never gets enough cooling (since the refrigerator is already "cold") to take it to near Zero F.

A straight refrigerator (no freezer section--or your do not use the freezer) and a straight freezer should work fine in cold rooms/weather--From what I understand, I live in a moderate temperature area and only have a few days of frost every year--at best.

-Bill

WaterWheel

7 cu/ft chest freezer has .7 kwh/day on the plate.       Kill a Watt meter showed actual average of .76 kwh/day over 2 weeks of 70-80 degree days last September.       Freezer in the garage.

westbranch

Monitor the consumption, our fridge in a cooler summer environment used about the same~  70% +- of the name plate,319 KwH (~ .6KwH per day) and we are very happy, 18 Cft capacity, top freezer
the new standards drop every year benefiting us all.

vtmaps

Photowhit said:

I can't recall the exact problem, but some freezers don't work properly when they are subjected to ambient temperatures below freezing. 

The Sundanzer DC fridges and freezers need to be in a warmer location than the food box temperature.  Their thermostats are NOT inside the food box.  I don't know if that is true for other brands of DC fridges that use the Danfoss compressor.

Regarding conventional AC freezers, some will not last long in ambient freezing temperatures because of motor lubrication issues.  Some old freezers in barns around here had heating blankets on the motors.  If you are looking at a new freezer, just look at the spec sheet... there will be a description of the ambient operating temperature limits.

Finally, the OP's signature shows a MSW inverter.   That may or may not work out too well... some motors don't get along with some MSW inverters (not all MSW waveforms are the same shape).  Motors today (and their windings) are made as light as possible for efficiency as well as cost.  The thin windings may not be able to dissipate the extra heat caused by a MSW waveform.

--vtMaps

just starting

Had a freezer to fridge conversion doing just fine since 9/15 so time will tell

Photowhit

just starting said:

Had a freezer to fridge conversion doing just fine since 9/15 so time will tell

Nice!

For others interested, we've had people here who suggest an external thermostat and probe aren't necessary with some chest freezers the thermostat can be adjusted to fridge temperature ranges, Not simple and mostly unmarked needing some trial and error. Can't think how to search for that thread now. I believe there was a link or 2 to beer brewer's forums...

kaipo_boy

My chest freezer is a magicchef, ~10 years old. Very inefficient, it has coils on the backside to dissipate heat (static, no fan) as opposed to the newer freezers that have 4 walls that get hot to get rid of heat. Mine is 7 cu ft and uses around 1.3kwh per day, if I remember right (measured with kill o watt meter but written down in the great black hole of my mind).  I have been thinking of dumping it and getting a sundanzer DC model.... I hear they use only 1/3 of that. But I have the great misfortune to live in Hawaii, of all the out of the way places. You'd think the post office never heard of us, judging by the cost to ship anything here.  I guess I will have to commiserate with my pina colada under the swaying palms tonight, damn.

aloha,

walt

westbranch

We got a nice GE fridge/freezer that is surprisingly efficient for an off the shelf model from Sears, and each year the specs get better and better, ie lower power needed...https://www.energystar.gov/index.cfm?c=most_efficient.me_medium_fridges_freezers

kaipo_boy

I was walking in my local costco tonight and they had a pretty 7 cu ft chest freezer on display... I checked the bright yellow tag on it, and it said the yearly consumption was around 220kwh per year... so around 0.6kwh per day.  If that tag is right, that's unbelievable; the newer freezers are very close to the Sundanzer, and cost a little over $200! (as opposed to the $1300 they want for the DC Sundanzer). I'm going to go back and check that tag again to make sure I noted the figures right... it makes sense to get that unit if the stats are correct.

just starting

When I get time and funds I will be testing out various chest freezers and limiting start surges so I can run on a small inverter sub 600 watt I have the temp sensors and some relays to make a frige priority over a freezer

Dave Angelini

For Reference the German Stecca DC 12/24 volt  freezer used about .3 KWH in a summertime garage. They are not cheap and are built to last a lifetime. They softstart the DC so there is absolutely no surge.

Hill_Country

I second the Steca DC 12/24 fridge/freezer (they can be run as a fridge or a freezer)...we have both a PF166 and a PF240 and we are very pleased with the fit/finish, as well as the how efficient they are.  I second Dave's usage as well!  You can read their specs at:  http://www.steca.com/index.php?Steca-PF-166-240-en  We are running them in the 24v mode (can be run either 12v or 24v).  Yes, they are pricey, but it all depends on what you're looking for.  We have both AC and DC circuits in our house and decided to mix and match appliances between DC and AC.  DC ceiling fans, DC fridge, DC freezer, and a couple DC LED lights, while we went with AC for our laundry, kitchen appliances, and some LED lighting.  We wanted what will be running the most to be the most efficient. 

BB.

Here is a two year old thread about the Stecca's:

http://forum.solar-electric.com/discussion/21072/powering-two-steca-fridge-freezers-from-a-48-volt-battery-bank

And using a small MPPT charge controller to drop from 48 VDC battery bank to 12 or 24 volt battery -> freezer.

-Bill

just starting

The price gets me I can convert a freezer with a digital temp control for two hundred or less and its fully adjustable well beyond the compressor's capabilities. And uses only 300 watts in summer heat for a 7.5 cf model. on fridge mode. I can buy two battery's for the money I save.would have to do the math to figure if its cost effective the hottest day here is maybe 80 degrees f for only a week or so.

BB.

Yep--the cost of battery bank+AC inverter+solar charge controller+extra solar panels + "very cheap" AC Freezer/Refrigerator can be a "better answer" than the DC version of these appliances.

In the end, I suggest that you do "both designs" on paper and see what works out best for you.

-Bill

kaipo_boy

Thanks, Hill Country.  The Steca's have an upper voltage limit of 31.5V...  hmmm. The system I'm building will use 20 NiFe cells, and I think the absorb voltage will be just over that at around 33V... by dropping out one cell and running a bank of 19 in series I would be at 31.35V, just under the Steca's limit but still doable. Interesting.  I too am thinking of mixing and matching appliances (some ac, some dc).

Just Starting, I did the same thing, bought an off the shelf a/c chest freezer (14.7cu ft) and used a Johnson Controls digital temp controller to turn the rig into a fridge. It works well, with a couple caveats; the freezer was never designed to be used as a fridge, so condensation collection on the bottom is problematic. I have to sop mine up with a towel every other week or it starts getting smelly in there. Also, the compressor hump/box inside the fridge is wonderful as a place to store milk and other heavy bulky items on top of, like a shelf, so you don't have to reach in all the way to the bottom... so it gets used a lot, but its STEEL on mine and after 1year there are some rust spots appearing. Can't get away from it, will have to shut down the fridge and repaint or glue on a rubber tray on it or something soon. Energy wise it is awesome, best thing I've done so far and made the biggest dent in my power bill.

Photowhit

...so condensation collection on the bottom is problematic...

So I guess a frost free model? I think standard freezer have a drain plug in the bottom.

just starting

The ones I use have a drain.so far so good. And condensation has not been a big problem its dry here in Colorado. We'll see how rain season is. And has aluminum interior but I took out the factory controls and mounted my control in a piece of lexan and siliconed in place. Funny thing I built my system for a real fridge but went this way instead so I could rud a washer also.

Hill_Country

Here's a usage table put out by Steca for the approximate energy requirements for various ambient temperatures and different fridge/freezer temperatures for their two DC models (PF166 and PF240).  Hopefully this helps others.  The Stecas come with a drain plug on the bottom for emptying residual water.  Condensation is definitely an issue for us here in Central Texas and we have to wipe the bottom of our fridge out every 2 to 3 months, depending on how humid it is.  Remember, however, that our off-grid place does not have air conditioning.  Both Stecas are inside. 

Also, keep in mind the operating temperatures for these units are from 50 deg. F to 109 deg. F.  Not sure what would happen if you are below the minimum operating temperature.  Just something to consider. 

BB.

I think the test standard for "energy star fridge/freezers" is around 0F inside and 95F ambient (-18C and 35C)--That brings the larger unit very close to 1kWH per day (365 kWH per year). Not very different than a similar energy start 120 VAC rated freezer.

-Bill

Dave Angelini

BB. said:

I think the test standard for "energy star fridge/freezers" is around 0F inside and 95F ambient (-18C and 35C)--That brings the larger unit very close to 1kWH per day (365 kWH per year). Not very different than a similar energy start 120 VAC rated freezer.

-Bill

What size are you comparing the larger unit with Bill?  The OP was looking at 4-7 cubic feet.
Not different  power maybe unless you lose your inverter to lightning or if you want to shut down the inverter while you are away because of lighting. I have a friend who uses his to drive to Costco 80 miles away in summer.
Lot's of other reasons someone offgrid might decide being the cheapest is not the best. I know that cost always seems to be the driver here, but from my perch looking back it really is only part of it offgrid.

Johann

Photowhit said:

...so condensation collection on the bottom is problematic...

So I guess a frost free model? I think standard freezer have a drain plug in the bottom.

May I interrupt?
 Does a frost-free model use more power?

just starting

I agree with you Dave when i have to shut down a inverter because of lighting two or three times a year it would be nice or when leaving on vacations 

just starting

But my freezers are in a cold room that's 35 f for about 20 hours a day so the fridge only cycles a few times a day for about 8 months a year

just starting

I would like just to buya danfoss compresser and build a costom  frezer/fridge  and use the heat some where else but that's a few years away

BB.

I had a manual defrost ~15 cuft upright freezer that was somewhere around 1 kWH per day. No longer made.

https://www.energystar.gov/productfinder/

You can find auto-defrost 10 cuft upright freezers in the 400 kWH per year range (1.1 kWH per day). 16.6 cuft are around 430 kWH per year (1.2 kWH per day).

For me, it ended up being better for our family to spend a bit more on electricity with auto defrost vs having to defrost the thing once or twice a year.

Frost Free units do seem to use a bit more energy (on average)--But the big deal is that they will run a defrost cycle about 2 times per day (at least the ones I have seen). The defrost cycle can take upwards of 600 Watts for a period of time while defrosting (vs the average of 120 Watts for running the compressor).

One of the members here tried disconnecting the defrost heater and found that the evaporator will begin to ice over and block airflow in as little as 24 hours. Which will "kill" efficiency.

If you can live with a chest freezer (or chest refrigerator conversion)--A 15.6 cuft manual defrost freezer is rated at 275 kWH per year (0.8 kWH per day as freezer or ~0.25 kWH per day as a refrigerator conversion).

The downside with almost all current fridge/freezers is that the standard induction motor compressor needs over 600 VA from the inverter just to start.

If you choose to go with a 12/24 VDC direct cooler or a 120 VAC unit + ac inverter + battery bank + larger solar array--Your choice.

If your power needs are very small otherwise--A DC system may make more sense for you. If your power needs are larger (well pump, lighting, cooking, washer, etc.), then a full 120/240 VAC solar power system may be a good choice.

-Bill

kaipo_boy

Johann, like Bill said, the 'frost free' models simply run a little current through the walls of the inside a couple times a day to keep the ice off. But that uses more power, so I just manually defrost the freezer every year or so by moving the contents into a large fishing cooler and then using a water hose to melt everything off inside. It is also a great time to throw out the old frozen meats from that hunt a long time ago and the frozen peas your kids forgot.

Condensation is an issue, yes.  I am vegan, although my family is not... but for me, the fridge needs to be just above freezing, but as close to it as possible so that my 7 lb bag of carrots from costco and all my greens purchased once a week from farm fair last as long as possible... my organic kale will usually last about a week in my converted fridge and at times I have kept them 2 weeks and they seemed fine. The bag of carrots, several months easily. But in order to get down that low, I have mine set at 36F in the winter, 35F in the summer, I am in hawaii so not enough temp variation, but enough that I see more ice if I don't do this) with only a 2 F 'dither'.  While this might seem high, in actual use the temp seems to hover very close to 36F and at night enough ice forms on the very bottom of the fridge to adhere to the walls and my every other week sopping up with towels ritual is also a 'chip the icebergs' off the wall ritual. The temp stratifies according to the air masses and the digital control's temp probe is about halfway down the box, so the very bottom of the fridge is just cold enough to freeze things slightly if they remain there a long time, although bottled stuff never freezes as it does not get cold enough to freeze anything with solutes in it.

Although mine does have a spigot/drain on the bottom as well, I never use it as it sits in my kitchen and I don't want to run a long hose to it. Also, the condensate level never gets very high so I don't know how useful a drain would be. There is usually a bit of ice frozen in that drain as well (on the inside).

Brock

We just bought an upright self defrosting freezer to replace our manual defrost 14ft chest freezer.  We went upright and frost free becasue the kids are now old enough to rummage through it and we were getting a LOT more frost in it and the kids could never find things and inadvertently hide things on us while moving things around to find their ice-cream     

The odd thing was we defrosted the chest freezer twice a year and when I let it do it's final defrost I noticed there must have been a LOT of ice in the walls and lid as they had condensation on them for 3 days and are still dripping water out after 5 days, so there must have been a lot more ice inside the walls of the freezer, which I hadn't considered and I am sure wasn't helping in the power usage.  So overall the frost free might help us.  The last time it was off for a couple of days was when we moved in to this house 10 years ago now...

I will be curious to see how it compares after a week, it looks to be right about 1 kWh a day right now and our old one was about 1.4 kWh a day.

Johann

BB, kaipo_bay, Brock,
Thank you for your comments.