Just how bad a small 'frige is

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Comments

  • 97TJ97TJ Solar Expert Posts: 57 ✭✭
    Re: Just how bad a small 'frige is

    I just got back from a week at the cabin I am building. The need for refrigeration with low power consumption and low initial cost led me to the so called freezer conversion. I used a separate thermostat and a 5.0 cu ft. freezer rated at 193 KWH annually. Keeping track with a kilo-watt meter my numbers came out like this. Elapsed time was 181 hours. KWH usage was 1.39. If I did my math correctly, that comes out to about 185 WattHours [-Bill] per 24 hour day. I kept the temp at 40 degrees which seemed cold enough for me. Ambient temps were about 60 at night and 75 to 80 during the day.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Just how bad a small 'frige is

    Another one for the books:

    Old Admiral 15 cu. ft. chest freezer (came with the house).
    Start-up 4.99 Amps, 562 Watts max.
    3.7 Amps running, 280 Watts (on 120 VAC lousy PF!)
    Averages 5.8 kW hours per day (pretty hot weather here just now: highs over 30C).
  • Volvo FarmerVolvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    Re: Just how bad a small 'frige is
    Averages 5.8 kW hours per day (pretty hot weather here just now: highs over 30C).

    That's HORRIBLE!

    We have a little 6 or 7 CF chest freezer that is rated at somewhere between 1.2 and 1.5 KWhr/day. I haven't tested it with the kill-a-watt yet, but I bet it's close. Is your freezer in a location that the sun shines on it, or could something else be wrong?
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Just how bad a small 'frige is
    Another one for the books:

    Old Admiral 15 cu. ft. chest freezer (came with the house).
    Start-up 4.99 Amps, 562 Watts max.
    3.7 Amps running, 280 Watts (on 120 VAC lousy PF!)
    Averages 5.8 kW hours per day (pretty hot weather here just now: highs over 30C).

    My Mom once had a SEARS 15 cu ft freezer that sucked back at least 5 Kwh/day. Horrible!
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Just how bad a small 'frige is

    Nope: it's just been very, very hot.
    The freezer is located in a ventilated "cold room" under the carport. The interior temp has been near outdoor high, so I've added a thermostatically controlled vent fan to draft air through. The running of the fan should decrease the interior temp and allow the freezer to run less. Naturally the weather has gotten cooler now. But I will test it some more. The power factor is still dreadful on the thing.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Just how bad a small 'frige is

    Update:

    Retested in cooler weather with the fan evacuating air from the room.
    3.1 kW hours per day, which is still terrible. The running Watts being twice a typical refrigerator is one issue.

    Still a caveat for anyone thinking of doing a chest freezer to 'frige conversion: make sure the freezer is economical to begin with!
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Just how bad a small 'frige is

    Frigidaire 20.3 cu. ft. upright frost free freezer.
    Energy Star rated @ 763 kW hours per year
    5.0 Amps @ 115 VAC

    Running on 122 VAC
    Idle draw: 0.1 Amps, 10 Watts
    Max Amps: 4.99, Max Watts: 565
    Running average (not in defrost): 1.89 Amps, 147 Watts
    Consumption: 1.92 kW hours per day (700 per year, so not too far off the rating)
  • RybrenRybren Solar Expert Posts: 348
    Re: Just how bad a small 'frige is

    I'm wondering if anyone has any experience with the Steca 5.9 DC Freezer/Fridge? http://www.uniqueoffgrid.com/App_UserFiles/Products/PDFFilesBROCHURE_UGP-5.9_EN_17458.pdf

    They claim:

    POWER CONSUMPTION When operating as a Fridge: 57-110 Watt Hours/Day
    (25C/77F AMBIENT): When operating as a Freezer: 300-570 Watt Hours/Day
    Subject To A 10 Month Consumer Evaluation In A Moderate
    Climate, Usage Averaged 120 Watt Hours/Day As A Freezer
  • inetdoginetdog Solar Expert Posts: 3,121 ✭✭✭✭
    Re: Just how bad a small 'frige is
    The latest numbers:

    Unexpectedly, the start-up surge remains at 4.99 Amps despite the refrigerant being cooled down. This is contrary to my experience with larger refrigerators. Perhaps the lesser volume of refrigerant equates to the motor/compressor being the main contributing factor; the change in refrigerant temp (being of such small volume compared to full-size units) not being a significant percentage of the work done.

    As the motor starts up, the pressure differential across the compressor is zero (hot side pressure == cold side pressure) and will stay low until a significant volume has been pumped. By the time that point is reached the motor will be out of its startup surge RPM range, so the effect will not show up there.
    I suspect that you are thinking of the problems in starting a compressor under load, as when it has been running and is shut off and then restarted before the pressure has had a chance to equalize slowly though the expansion valve. In that case you would get the same initial surge current with the motor RPM at zero, but because of the pressure differential the motor may not produce enough torque to get up to operating speed at all. It is the duration of the surge current that trips out the motor overload or the CB in that situation.
    SMA SB 3000, old BP panels.
  • pdxr13pdxr13 Registered Users Posts: 6
    Re: Just how bad a small 'frige is
    My Mom once had a SEARS 15 cu ft freezer that sucked back at least 5 Kwh/day. Horrible!

    Sixty cents a day to have rock-hard chocolate ice cream and 20 cubic feet of -30F meat doesn't sound so bad, unless you have to do it off-grid.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Just how bad a small 'frige is
    pdxr13 wrote: »
    Sixty cents a day to have rock-hard chocolate ice cream and 20 cubic feet of -30F meat doesn't sound so bad, unless you have to do it off-grid.

    $220.00 per year would purchase some groceries too. :D
  • Dragonlady5Dragonlady5 Registered Users Posts: 19
    Re: Just how bad a small 'frige is

    If anyone would like some oscilloscope screen shots of some appliances starting surges do let me know. E.g. Danby bar fridge rated at 1.7 Amps, -drawing PEAK current of 21 Amps. A 1300 Watt Turbo (halogen) Oven drawing almost 100 Amps PEAK. A 1200 Watt microwave (with UL label stating maximum power of 1460 W) drawing 17 Amps RMS (2000 W).
    Goes to shows why sizing inverters is ... troublesome.
    There are many people who post here expecting to save power in an off-grid situation by using a "small" refrigerator, as opposed to a large one. Having an unused Danby "cube" refrigerator and my UPM meter at hand, I decided to see just what the thing would use.

    Initial start-up surge: 4.99 Amps (@ 118 Volts = 588 Watts). Running average (so far) 100 Watts.
    With the thermostat set "half way" we'll see how many kW hours it consumes in 24 hours.

    Considering that my full size refrigerator only uses 130 Watts running, it doesn't look good for the "cube". :cool:
  • BB.BB. Super Moderators Posts: 26,768 admin
    Re: Just how bad a small 'frige is

    You can post low to medium resolution photos (3 or so per post) here directly. I am sure people would be very interested in seeing the wave forms.

    When I looked into surge currents decades ago, there was not any real limit (that I could find) on a 15 amp branch circuit surge current. I sort of came to the conclusion that the computer disc drive industry (these were "big" rack mount 1/2 GByte disc drives), would pull upwards of 45 amps on a 120 VAC 15 amp circuit and "everybody" was fine with that.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • KnowledgeSpongeKnowledgeSponge Solar Expert Posts: 163 ✭✭✭✭✭
    Re: Just how bad a small 'frige is

    Is there a tread somewhere here like this one, but devoted to small window Air Conditioners instead of Small Refrigerators?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Just how bad a small 'frige is
    Is there a tread somewhere here like this one, but devoted to small window Air Conditioners instead of Small Refrigerators?

    Closest we've got to that: http://forum.solar-electric.com/showthread.php?16201-Fedders-5000-BTU-A-C-test

    :D
  • BB.BB. Super Moderators Posts: 26,768 admin
    Re: Just how bad a small 'frige is

    There are quite a few. Click on this Google Link or enter this search term (or similar) into Google:

    off grid A/C site:wind-sun.com

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dragonlady5Dragonlady5 Registered Users Posts: 19
    Re: Just how bad a small 'frige is

    I have (I hope) attached three captures:
    1. A Danby bar fridge rated for 1.7 Amps continuous on utility. On start, drawing >14.5 Amps RMS, with a peak of 12.
    2. Danby 6500 BTU AC on 2500 Watt inverter (soft start). On start, drawing 34 Amps RMS, with peaks > 51 Amps.
    3. Panasonic 1200 Watt MW oven. UL label rating of 1480 Watts. On power 10 for the first minute drawing 17 Amps.

    I have many more, halogen oven and flood lights, air compressor, skill saws, non-power factor corrected power supplies, photographic strobes.....

    Only way to really characterize surges is to scope it. Meters (Kill-A-Wat, DVM or analogue) typically do not show short duration peaks which the source supply (inverter) must deliver.



    BB. wrote: »
    You can post low to medium resolution photos (3 or so per post) here directly. I am sure people would be very interested in seeing the wave forms.

    When I looked into surge currents decades ago, there was not any real limit (that I could find) on a 15 amp branch circuit surge current. I sort of came to the conclusion that the computer disc drive industry (these were "big" rack mount 1/2 GByte disc drives), would pull upwards of 45 amps on a 120 VAC 15 amp circuit and "everybody" was fine with that.

    -Bill
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Just how bad a small 'frige is

    Every time I read the subject line to this thread (and that happens a lot since it's a sticky), it kicks off a song in my head: Otis Redding singing "That's How Strong My Love Is". Does that happen to anyone else or am I just weird? :D
  • inetdoginetdog Solar Expert Posts: 3,121 ✭✭✭✭
    Re: Just how bad a small 'frige is
    ggunn wrote: »
    ... or am I just weird? :D

    Yes, you are. And that song in your head bit is strange too. :-)
    SMA SB 3000, old BP panels.
  • Ralph DayRalph Day Solar Expert Posts: 871 ✭✭✭
    Re: Just how bad a small 'frige is

    Gotta watch those ear worms, they can stick with you all day or...All night looong, all night...


    Ralph
  • sanjuansunsanjuansun Registered Users Posts: 1
    Re: Just how bad a small 'frige is

    Did you get any answers? Looking at thisFridge to replace my 15 yr old sundanzer.
  • BB.BB. Super Moderators Posts: 26,768 admin
    Re: Just how bad a small 'frige is

    SanJuanSun,

    What refrigerator are you looking at?

    What size of off grid power system do you have (Inverter wattage, battery bank AH/voltage, solar array wattage, etc.)?

    And welcome to the forum.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • oil pan 4oil pan 4 Solar Expert Posts: 613 ✭✭✭✭
    I have a full sized 2013 built Kenmore that uses around 1KwH per day with the ice maker going. Nothing fancy, freezer on top, fridge down low, condenser coils and fan underneath.
    It does have the heater that goes around the freezer seal. I Kill-a-watt metered it some time ago and cant remember if it draws 10 or 20 watts for the seal warmers.
    I say put the seal warmers on a motion detector or timer, let the darn freezer door freeze shut in the middle of the night or when no one is home for all I care.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • JohannJohann Solar Expert Posts: 239 ✭✭✭
    dhsola wrote: »
    Re: Just how bad a small 'frige is

    I checked the usage on a Domestic refer/freezer from a camper (circa 1986); from warm, with only a case of water inside of it, I think it burned 375w all night.

    I have an unused, 20 year old, 19 cu in refer/freezer that burns 275w (self defrost).

    And believe-it-or-not, I have a (in use) circa 1950's Westinghouse refer that burns 160w - 180w. Kinda like this one:

    Attachment not found.

    Attachment not found.

    The little freezer hangs down from the refer ceiling. The compartment on the bottom is where the huge compressor sits. Walls/door are 3" thick. I added EPS foam to back and bottom and layed reflectix over the rounded top/sides and an additional piece inside the refer door. This old refer, combined with a 7.5 cu in chest freezer burns less juice than the 19 cu in self defrost refer (1-1/8" thick walls).

    I've had this old Westinghouse for 30 years. When I acquired it, it was sitting outside in the snow - still working. I haven't done anything to this refer but paint it! It's truly amazing how things used to be built to last.

    And the size of the old Westinghouse compressor is about 3 times bigger if it is the original than any of the new fridges/compressors.
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