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lithium iron phosphate kit

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  • #16
    prices

    lithium isnt 1$/w
    its .375$/w or 1920$ for 4.8kw
    why do you say they last twice as long? lithium is rated for 2000 cycles to 80% capacity? the only way to get more cycles with the rolls is if you only do 10% depth of discharge with it no? I have read that 10% DoD on lead = 4000-5000 cycles, but 25% DoD makes it down to 1000-2000 cycles. is this correct?

    The actual kw used per day i expect to be 2kwh, many calculators i have found say to get 2kwh/day i need usually around 1kw in panels to account for the poor months.
    I would need i think 12-15 hours each day worth of no sun energy. So 1kwh to 1.25kwh.
    So in order for there to be only 10% depth of discharge with lead acid, i would need a 12.5kwh capacity battery no?
    that would cost 2750$ according to the .22/w figure.

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    • #17
      Originally posted by muffildy View Post
      why do you say they last twice as long? lithium is rated for 2000 cycles to 80% capacity? the only way to get more cycles with the rolls is if you only do 10% depth of discharge with it no?
      Click this link, scroll to the bottom of the page and look at the graph for the Rolls 5000 Series. At :

      20% DOD = 5000 cycles
      50% DOD = 3200 cycles
      80% DOD = 2100 cycles

      They carry 10 year factory warranty. What warranty do your Chi-Com batteries come with from the factory?

      You had better be careful with those cheap Chi-Com LFP batteries (Thunder Sky). Lot's of them blowing up in DIY EV's and only getting a few hundred cycles. Good ones from A123 Systems (2000 cycles) will cost $2/watt. They even catch fire. Read about Chevy Volt Recalls
      MSEE, PE

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      • #18
        Originally posted by muffildy View Post
        The actual kw used per day i expect to be 2kwh, many calculators i have found say to get 2kwh/day i need usually around 1kw in panels to account for the poor months.
        What is your location or zip code?
        MSEE, PE

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        • #19
          32708
          sunbelt, 4-4.5 hours of sun no?
          lithium will only catch fire if you try to drain them really fast
          so of course you would need a current limiter of some sort in the system

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          • #20
            Originally posted by muffildy View Post
            32708
            sunbelt, 4-4.5 hours of sun no?
            4.61 Sun Hours is what I get in December.

            So to generate 2 Kwh/day minimum where you are at in December worse case using FLA batteries and MPPT controller is:
            2000 wh / .66 / 4.61 = 657 watts, round up to 700 watts.

            Using LFP:
            2000 wh / .72 / 4.61 = 602 watts, round up to 650 watts.

            Now if you use a cheap PWM controller then using:

            FLA = 2000 wh / .5 /4.61 = 867 watts round up to 900 watts
            LFP = 2000 wh / ..56 / 4.61 = 774 watts round up to 800 watts.

            One thing you are not doing is comparing apples to apples with respect to battery sizing. Minimum FLA is 5 days, and minimum for LFP is 4 days. So with FLA you need 10 Kwh capacity and 8 Kwh for LFP.

            I really do not care what battery chemistry you use, but so far from what I gather, the data you used to compare and base a decision is inaccurate and flawed.
            MSEE, PE

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            • #21
              Originally posted by muffildy View Post
              lithium will only catch fire if you try to drain them really fast
              No they catch fire when charging.
              MSEE, PE

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              • #22
                overcharge

                only if you overcharge them, then they can be quite explosive.
                charging them is a chemically endothermic reaction in itself, the battery only gets hotter because of other factors.

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                • #23
                  Good luck and 73 to you.
                  MSEE, PE

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                  • #24
                    code

                    not familiar with that code.
                    Anyhow.
                    im not dead set on lithium
                    in fact im hoping and praying the EOS energy storage (http://www.eosenergystorage.com/) will develop and market their new zinc air battery for off-grid use; currently it looks like they are trying to become a player in grid for the power company though.

                    Ever heard of http://renogy.com/index.php?c_id=14 ? their prices look pretty good, and they look like a US manufacturer, but im not sure if theyre just an importer.
                    It does look like now is the time to buy solar panels because of this chinese oversupply though, its too bad US companies are crying and so imports even if ordered right now will be tariffed if they decide to.

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                    • #25
                      73 = Best Wishes.
                      MSEE, PE

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