10 cu ft Magic Chef Fridge

54d1854d18 Solar Expert Posts: 78 ✭✭✭
My brother just picked up a 10 cu ft Magic Chef fridge for his off grid cottage,
it has auto defrost in it and I was wondering if anyone has disabled this on
their fridge to reduce consumption.

Any comment s out there??

T

Comments

  • BB.BB. Super Moderators, Administrators Posts: 31,082 admin
    Re: 10 cu ft Magic Chef Fridge

    If there is a circulating fan and the evaporator is behind a duct--Then disabling the auto defrost will usually cause the evaporator to ice up and block air flow after one to a few days.

    I just had to replace the defrost timer (12 hour timer, ~1-2 hours of defrost every 12 hours) on my larger upright freezer--After about 4-5 days, it was a solid mass of ice and frost in their and needed to be taken apart and defrosted.

    In general, trying to disable the defrost system will cost you more electrical power on average as the cooling efficiency drops.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: 10 cu ft Magic Chef Fridge

    It always makes me sad when I hear of people buying these designs of fridge for off grid use. They're usually not suitable for off grid compared to simpler designs without the electronics, defrosters etc.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: 10 cu ft Magic Chef Fridge

    to add to that wayne i will go as far to say that they aren't making refrigerators very good regardless of application. if not suitable for off grid then it can't be all that good or efficient on grid either in spite of e star figures. they just aren't designing them correctly and they don't care. they also want you to have to replace them in 5yrs to 10yrs just like the old attitude from the detroit car makers. for instance in what circumstance is it good to start a refrigerator off in defrost? be it for the first time or after an outage it is detrimental and a waste with the latter amounting to spoiled foods that otherwise would've been fine with a straight refrig start up. needless to say it is at a minimum a big waste of power. what were they thinking?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: 10 cu ft Magic Chef Fridge

    Agreed.

    They can put microprocessors in them so you get TV & Internet on the door, but nothing for reducing start-up current or assessing coolant pressures and maximizing refrigeration efficiency based on interior and exterior temps, etc. If they did do this it would be marketed at a very high price and the average consumer would not see the value because the made-over old designs are "good enough".

    I would very much like it if they weren't so noisy too; the big, expensive Maytag in my kitchen sounds like a diesel truck when it runs. Oddly enough they made the effort with the dishwasher.

    Okay, enough from the grumpy old men contingent. :p
  • 54d1854d18 Solar Expert Posts: 78 ✭✭✭
    Re: 10 cu ft Magic Chef Fridge

    I never thought about how quickly they may frost up,
    I thought it would take weeks or more before needing to be defrosted.

    Does anyone have suggestions as to what fridge to get for off grid,
    I need something in the size of 10 cu ft, basically I am limited
    to 24" wide, so I can't go any wider than that.

    Thanks,

    T
  • BB.BB. Super Moderators, Administrators Posts: 31,082 admin
    Re: 10 cu ft Magic Chef Fridge

    You can start with the US based Energy Star listings (there are many 10 cuft models that are built in Canada--So that may give you some local options). It appears that most are are between ~300 to 400 kWH per year. That is pretty much what a good 16-20+ cuft refrigerator/freezer draws too (towards 400-450 kWH per year, I even lucked out and found a 17 cuft model that draws ~320 kWH per year, but that one is already out of production).

    Or, you can look at a chest freezer conversion and draw less than 100 kWH per year (on the order of 0.25 kWH per day). Your spouse (if you have one), may not like a chest freezer for food access).

    How big of off grid power system are you looking at (solar array wattage/battery bank AH and voltage)? With automatic defrost, you are getting into the issue of defrost timers. Refrigerators/Freezers may have an electronic timer that sets to defrost cycle whenever power is cut (an AC inverter with standby mode--looks for loads ~once per second then turns on when load >6 watts). There are still many models (cheaper ones?) that have mechanical defrost timers that will defrost every ~12 hours--With search mode, it may defrost every 24 hours (assuming fridge compressor runs 1/2 the time).

    Basically, a "real" refrigerator/freezer will push you from a 1 kWH per day system to about 3.3 kWH per day because of the refrigerator load + (usually) running a larger inverter 24x7... (a medium size inverter will draw 10-20+ watts "just turned on").

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: 10 cu ft Magic Chef Fridge

    I did it backwards: got the refrigerator, built the power system to run it.

    Oh wait, that's not backwards. :p
  • mikeomikeo Solar Expert Posts: 386 ✭✭✭
    Re: 10 cu ft Magic Chef Fridge

    I have just bought one of these fridges from Home Depot for about 300 dollars. They are Chinese built and are sold under the name Vissani as well as Magic Chief. They are Energy Star rated at 312 kWh/year which is pretty good for the price and so far seems like a nice little fridge. I will let you know about the longevity as time goes on. I put one in my 1956 Spartan Imperial Mansion trailer as it was one of the few locally available that would fit the existing opening that I had to mount it in. It seem like it would be a good match for a small solar drawing a rated 855 watt hours each day. Seems to me about 600 watts of panels should run it in most of the US. Often it may draw even less than rated but I wont know until I put my watt hour meter on it when I get the trailer moved to it permanent location.
  • Volvo FarmerVolvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    Re: 10 cu ft Magic Chef Fridge
    It always makes me sad when I hear of people buying these designs of fridge for off grid use. They're usually not suitable for off grid compared to simpler designs without the electronics, defrosters etc.

    I completely disagree with this statement. It is almost impossible to prove, because modern manual defrost refrigerators are not being manufactured any more, but a frost-free design wins in efficiency every time. Sure, there is the extra load of the heater coming on once in a while, but the improved thermal efficiency of fan forced air over a not-frosted-over evaporator more than makes up for the extra power used by the defrost system. I have also compared similar models with a static cooled condenser and a fan cooled condenser and the one with the fan was more efficient.

    http://michaelbluejay.com/electricity/refrigerators.html

    "Suitable for off grid" is a pretty big blanket statement. I personally think that a refrigerator that uses around 1KWHR/day is perfectly suitable for off grid and I don't care if it uses electronics or defrost systems or a flux capacitor to achieve it. More simple does not always equal more efficient.
  • silvertopsilvertop Solar Expert Posts: 155 ✭✭✭✭✭
    Re: 10 cu ft Magic Chef Fridge
    I completely disagree with this statement. It is almost impossible to prove, because modern manual defrost refrigerators are not being manufactured any more, but a frost-free design wins in efficiency every time. Sure, there is the extra load of the heater coming on once in a while, but the improved thermal efficiency of fan forced air over a not-frosted-over evaporator more than makes up for the extra power used by the defrost system. I have also compared similar models with a static cooled condenser and a fan cooled condenser and the one with the fan was more efficient.

    http://michaelbluejay.com/electricity/refrigerators.html

    "Suitable for off grid" is a pretty big blanket statement. I personally think that a refrigerator that uses around 1KWHR/day is perfectly suitable for off grid and I don't care if it uses electronics or defrost systems or a flux capacitor to achieve it. More simple does not always equal more efficient.

    I have to agree with Volvo, we have had a 18 cf. Samsung French door with bottom freezer for about two years pulls about 980 Watts a day completely off grid no worries. when the defrost heater kicks in it pulls about 200 Watts but doesn't run that long. This is smaller than what you would buy at say Home Depot we had to order on line. I would highly recommend it! We do have to live in the real world......
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: 10 cu ft Magic Chef Fridge

    and i'll disagree should the refrig start its cycle off in defrost. i think that after the 50 or so years autofrosts have been around that they should be improving things in this area rather than screwing it up more.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: 10 cu ft Magic Chef Fridge
    niel wrote: »
    and i'll disagree should the refrig start its cycle off in defrost.
    No, but it may reset the defrost timer to a value less than maximum. I can see a reason for doing that.
    And if the refrigerator is using a temperature measurement of the evaporator coil to detect a buildup of ice, instead of using a timer, it may not realize that the compressor was just running and so decide to do a defrost cycle just in case.

    Some of the auto-defrost circuits are smarter than they were before, although that may not be a good thing in the long run.
    SMA SB 3000, old BP panels.
  • 54d1854d18 Solar Expert Posts: 78 ✭✭✭
    Re: 10 cu ft Magic Chef Fridge

    As usual, a lot of good feedback, and I'm looking forward to
    hearing back from Mikeo on the performance of this fridge,
    I am limited in space for installing one, I only have 24" for the width.

    T
  • goingwestgoingwest Registered Users, Users Awaiting Email Confirmation Posts: 1
    I am trying to run this frig with a 400 watt invertor. Power”light” runs but compressor does not. Unit label shows [email protected] so that should be 160 watts. What are others using or finding they draw?  Thanks 
  • 706jim706jim Solar Expert Posts: 371 ✭✭✭✭
    There's a possibility that your 400 watt inverter can't handle the surge needed to start the compressor. Odd that the inverter doesn't show an overload however. I run a 1500 watt inverter with a huge surge capacity. When the fridge starts my lights will briefly dim indicating a fair surge load. My fridge is similar running at around 140 watts or so.
    Island cottage solar system with 2400 watts of panels, 1kw facing southeast 1kw facing southwest 400watt ancient Arco's facing south.Trace DR1524 MSW inverter, Outback Flexmax 80 MPPT charge controller 8 Trojan L16's. Insignia 11.5 cubic foot electric fridge. My 27th year.
  • BB.BB. Super Moderators, Administrators Posts: 31,082 admin
    It does depend on the refrigerator type... The standard compressor type refrigerator may take ~120 Watts or so running, but can take 5x that amount starting:
    • 1.4 amps * 115 volts * 5x starting surge = 805 Watts (technically VA--But for another post/discussion)
    In general, for a "reliable" off grid system, the AC inverter should be around 1,200 to 1,500 Watts minimum. Less than 1,000 Watt AC inverter, you can have overloading issues.

    Other things to check... The defrost heater (for evaporator internally) and sometimes "anti-sweat heaters" in the door frames can take upwards of 600 Watts during the defrost heater (there can be a Calrod heater that turns red hot inside the refrigerator to quickly defrost ice buildup).

    And, check your battery size, and DC wiring. Put a volt meter on the DC input to the AC inverter when starting... You want to see nothing less than ~11.5 to 12.0 volts minimum during starting (most 12 volt inverters "shutdown" at 10.5 volts or so). To small of battery bank (need something like a 400 AH @ 12 volt battery bank minimum for a 1,000 Watt inverter) and short heavy wire to carry the high surge current:
    • 1,000 Watts * 1/0.85 AC inverter eff * 1/10.5 volts battery cutoff = 112 Amps
    And you don't want more than 0.5 volt drop in the 12 VDC wiring from the battery bank to the AC inverter (too much drop, the inverter shuts down).

    Yes--AC inverters typically supply around 2x rated Watts/VA for starting surge power of a few seconds--But standard induction motor compressors are very hard to start. There are games you can play to possible run on a smaller AC inverter--But this is a significant project itself.

    There are "inverter" and "linear" compressor based refrigerators that have very low starting surge current... They tend to be rare (at this time) in the USA for smaller/simple refrigerators--But are more common in Mexico and other countries.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • lucman2lucman2 Registered Users Posts: 3
    RV refrigerators run on propane or 120v or 12VDC and don't  have defrost heaters or fans. Take a look at them may fit your application for off grid.
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