I need help for a Small system for a solar dummy.

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  • SunEagle
    Super Moderator
    • Oct 2012
    • 15123

    #16
    Originally posted by Janachovsky
    Got ya, so in series would need 2- 12v @ 450ah

    ​​​​​
    The problem is finding (or even moving) a 12volt 450Ah battery. They would be very heavy even if you could find them.

    The only way to build a 12v 450Ah battery system would be to use 6 x 2v 450Ah batteries wired in series.

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    • Sunking
      Solar Fanatic
      • Feb 2010
      • 23301

      #17
      Originally posted by Janachovsky
      Got ya, so in series would need 2- 12v @ 450ah
      No such thing as a 12 volt 450 AH battery. You are stuck inside a 12 volt Toy Box. Batteries are 2-volts. If you need 24 volts @ 450 AH, you buy 4 x 6-volt 450 AH batteries and wire them in series. Never Ever parallel batteries unless absolutely necessary, and rarely ever necessary unless you need more than 4000 AH. Large batteries come in 2, 4, and 6 volts. Get out of the 12 volt box.

      FWIW if a 12 volt 450 AH battery existed, and there maybe some made for railroads, would weigh 300 or more pounds. Even a 6-volt 450 AH battery has some weight of 150 to 160 pounds.
      Last edited by Sunking; 04-09-2017, 10:57 PM.
      MSEE, PE

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      • Wy_White_Wolf
        Solar Fanatic
        • Oct 2011
        • 1179

        #18
        Originally posted by SunEagle

        Well that freezer is going to draw about 200 watts (115v x 1.7amp = 196watts). But not continuously. So lets say it runs 10 hours a day at that load. That calculates to 2kWh.

        I am still not sure what that fan draws but lets say you are correct and it is .6kWh/day or ~600wh.

        Now add that 600wh to the 2000wh and you have two loads at about 2.6kWh a day.

        To size your battery system, you need one that can delivery ~ 2600wh x 4 = 10400wh.

        A 12volt battery system would have to be 10400wh / 12v = 870Ah.
        A 24volt battery system would be about 10400wh / 24v = 435Ah

        Depending on where you live you will need an 80A MPPT and about 1000 watts of panels for a 12volt battery. And about 1/2 that 40A MPPT and 500 watts for a 24v battery system.

        Now that does not include any wiring, framework, inverter, fuses, etc. So go check out the prices of that battery system and lets us know if it would be cheaper than running a 110v AC line?
        The wattage of the array does not change with battery voltage. It needs to be 1000 watts with either 12 or 24 vdc.

        WWW

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        • SunEagle
          Super Moderator
          • Oct 2012
          • 15123

          #19
          Originally posted by Wy_White_Wolf

          The wattage of the array does not change with battery voltage. It needs to be 1000 watts with either 12 or 24 vdc.

          WWW
          Oops. You are correct. Thanks for checking my math.

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