Fridge 7 amps vs 2.1 amps

sumby17
sumby17 Registered Users Posts: 1 ✭
in Energy Use & Conservation #1

So it seems a basic decision on buying a fridge of 2.1 amps (although defrost says 545w) inverter (talking of a LG big fridge ) vs a fridge with 7.1 amps.

Here is my question that I need help. Why would the yellow energy tags consumption are basically the same? Which one will be the best?

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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #2

    The run amps of 2.1A plus the defrost of 4.54A comes to 6.64A, the LG may be including the defrost in the maximum current, the LG being an inverter type may be marginally more efficient due to not being an on off cycle. The ability to modulate the run speed may be responsible for the close energy ratings, the benefits in an offgrid application favor the inverter type due to the lack of surge current typically found with regular type refrigerators.

    For offgrid, if money isn't a barrier go for the inverter type, you won't regret it.

    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    #3

    If your inverter can handle the startup load and the yearly energy consumption is the same, then I think it makes no difference.

    I am available for custom hardware/firmware development

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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,109 ✭✭✭✭✭
    #4

    I believe those numbers are worst case "peak" numbers. My 14 cu. ft. Hotpoint refer in Baja drew just over 1 amp when running, fresh out of the box. After break in time it settled at .75 amp @120 Vac. Of course start up current will be considerably higher, the kill-a-watt meter says .75 amp running.current.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,623 admin
    #5

    The input current on the name plate for appliances are pretty hit and miss on what they really draw... Typically worst case continuous current--But not including starting surge (which for 120 VAC 15 amp circuits can hit ~45 Amps for a few cycles (1/10th second or less).

    The big thing with inverter (and linear) compressor refrigerators is the low surge current (near zero surge over normal running current).

    A big value for small off grid systems (can get away with smaller AC inverter and, possibly, even a slightly smaller battery bank--less surge power draw).

    However, once you have a system that is >~1,200-1,500 Watts, an inverter based refrigerator is not worth paying a lot of extra money for (although, you may notice less "light flickering" as the compressor starts).

    For a frost free fridge or freezer, you are still probably looking at around 600 Watt draw for the defrost element (it was a kick seeing a glowing red heating element in my freezer when I had to manually defrost by removing the interior rear sheet metal to defrost the evaporator--A glowing Calrod element in a deep freezer--Just not something you expect).

    Overall, the energy usage for either (Energy Star Rated, high efficiency) standard compressor or inverter/linear compressor refrigerators--I have not seen any big difference ("big" for me is 10% or greater difference between unit A and unit B).

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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