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Battery powered Refrigerator (or Let CA Purchase my Charger and Inverter)

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  • Battery powered Refrigerator (or Let CA Purchase my Charger and Inverter)

    Here is a real world use case. I have just put a 14.5 Refrigerator/Freezer in my basement at my cabin and it works well, but it is currently powered by an extension cord to an outlet shared by a lot of other loads. Getting a new circuit will cost about $350. Here is an alternative.

    Frigidaire customer service says the load is 500w. They will not tell me the cold cranking amps or surge watts. Someone in customer service tells me I run it off of a generator but they don't know the difference between MSW and PSW. From Energy Star the average is 780 Wh / day.

    Frigidaire - 500W
    Surge - 1000W ? (Guess)
    Load - 780 Wh / day
    Cost of electricity = 14.496
    TOU with baseline of 13.8 Summer, 25.7 Winter gives me 10 hours at 1 cent / kWh

    I propose:

    2 6v US Batteries US2200XC @ 232AH $99.9 each ($20 core) - published cycles 1150
    Samlex SSW-600-12A Inverter for $173
    Samlex SEC1230A Smart Charger with DC UPS for #204.

    At 50% DOD I calculate the cost of battery power to be 12.48 cents / kWh. I propose to pro-rate the inverter and charger ($173, $204) over ten years. That brings the cost to 14.84 cents / kWh. My current fixed rate at baseline is 14.496.

    The batteries at 50% should run the load for 42.8 hours.

    Setup:
    110v -> Timer -> Samlex DC-UPS -> Battery -> Inverter -> Refrigerator

    The timer will supply power to the charger from 10PM to 8AM when power costs 1 cent / kWH. Should take 6 hours. That brings my cost of power to 15.84 cent per kWh. That is a savings of $88 per year based on non-TOU with no load shifting of cheap power.

    Another way of looking at it, is that I pay for my inverter and charger with the money I did not spend having a new circuit installed for the refrigerator. Then the cost of electricity is 12.48 cents per kWH + 1 cent for TOU baseline = 13.48 cents / kWh, lower than my current non-TOU baseline of 14.5 cents / kWH.

    If I switch to TOU I will also put a timer on my Electric Hot Water Heater to only heat during low TOU baseline rates.

    What did I forget? Does this make sense?

    ###
    Just got an email from Interstate. Asked about Costo golf cart batteries. They are a more economical version of the XHD with 207 AH and he said they get the same cycles, which are 650 @ 80% DOD and 1220 @ 50% DOD. That brings the cost down to 11.09 cents / kWh @ 50% DOD. So far that is the best I have found.
    ###
    Last edited by lkruper; 09-28-2015, 03:49 PM. Reason: Added Costco

  • #2
    Something is way wrong.

    I doubt the compresser load is 500w. It might be 500w for 9 minutes while the heater for the ice tray or defrost is on.

    Running power is likely to be in the 150w range

    Surge will need about 1Kw inverter to handle the 5x running wattage starting surge

    Frigidaire - 500W
    Surge - 1000W ? (Guess)
    Load - 780 Wh / day
    Your info says the fridge will run less than 2 hr per day ( 2hr = 1 KWh )
    Most new energy star units would run about 20-30% of the time.
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

    Comment


    • #3
      Originally posted by Mike90250 View Post
      Something is way wrong.

      I doubt the compresser load is 500w. It might be 500w for 9 minutes while the heater for the ice tray or defrost is on.

      Running power is likely to be in the 150w range

      Surge will need about 1Kw inverter to handle the 5x running wattage starting surge



      Your info says the fridge will run less than 2 hr per day ( 2hr = 1 KWh )
      Most new energy star units would run about 20-30% of the time.
      The useless user manual says 6 amps @ 110v. Customer service said 500w. Multiple customer service people could not tell me the cranking amps. One got through to a technical person who knew what that was, and then they said it was unofficial so they could not tell me. The last one said it would run on a generator, but the person she asked did not know the difference between PSW and MSW inverter.

      So what I did was take the Energy Star documentation and back-calculated to one day's energy usage which is the 780w / day. Before I do anything I will put my Kill-o-watt on it for a day. I took the 500w and 2X surge estimate to use to size the inverter.

      Comment


      • #4
        Originally posted by lkruper View Post
        The useless user manual says 6 amps @ 110v. Customer service said 500w. Multiple customer service people could not tell me the cranking amps. One got through to a technical person who knew what that was, and then they said it was unofficial so they could not tell me. The last one said it would run on a generator, but the person she asked did not know the difference between PSW and MSW inverter.

        So what I did was take the Energy Star documentation and back-calculated to one day's energy usage which is the 780w / day. Before I do anything I will put my Kill-o-watt on it for a day. I took the 500w and 2X surge estimate to use to size the inverter.
        You really can't trust any nameplate information on an appliance because they usually post the worst or highest data for usage. Most times the actual consumption is much less then the posted data.

        That is why the kill o watt meter is very useful.

        Comment


        • #5
          Originally posted by Mike90250 View Post
          Something is way wrong.

          I doubt the compresser load is 500w. It might be 500w for 9 minutes while the heater for the ice tray or defrost is on.

          Running power is likely to be in the 150w range

          Surge will need about 1Kw inverter to handle the 5x running wattage starting surge



          Your info says the fridge will run less than 2 hr per day ( 2hr = 1 KWh )
          Most new energy star units would run about 20-30% of the time.
          I am wondering if I can get the technical information I need by finding out what compressor is used in a particular refrigerator and then calling that manufacturer, thus bypassing Frigidaire. I know that most of the good AC/DC fridges use the Danfoss compressor. Is there a limited marketplace for compressors for conventional refrigerators as well?

          Comment

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