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  • Actually it would be good for another topic thread.

    The way these cells are shoe-horned into solar bank use is if they are excessively large in capacity compared to the need (which usually *never* meet the typical solar 2-3 day minimum!), or are so cheap, because the cells are either old stock, surplus crash damage, counterfeit, and the like that this is the only way the project makes any financial sense.

    But back to life-cycle - the way we get any cycle life beyond about 360 (maybe a year's worth of cycling) cycles, is to purposely engineer the use-case to only use a small amount of cycle capacity.

    Which brings us back to LFP vs other chemistries:

    Salesman-type data: (only used for comparison since we murder our batts in the real world)

    LifePo4 - 2000 cycles or more to 100% DOD
    NON-LFP - typically about 360 cycles to 100% DOD

    So right off the bat, there's no comparison. When one takes the vehicular use-case data away, and put into our application, things don't look so bright for non-lfp, unless on is doing a "one-off" diy project that nobody else is going to duplicate - at least not over the counter.

    And that's kind of the point - NOBODY would "diy" a non-lfp bank, if they had to pay FULL PRICE for quality Tesla cells, bought directly from Tesla as if they would! It's one reason why A123 stopped selling to diy'ers long ago, and the gray market, rejects, and counterfeits showed up. Heh, we've been through this all before.


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    • Bravo!

      This thread was an interesting read. Pulled from the bash-em-all-to-hell toilet, at the brink of being closed, only to end up being constructive and informational.

      All I have to add is that the UL, in UL 1974 entitled "Standard for Safety for Repurposing Electric Vehicle Batteries" says "UL wants to help manufacturers make sure the batteries that power these vehicles are used to their full potential. Today, rather than simply disposing of the batteries when they no longer provide the power needed by EVs, they can be repurposed. However, for this to be possible, the batteries must first be safe, meaning every pack must be evaluated according to established standards to determine its condition, safety and energy capacity."
      https://standards.globalspec.com/std/13082523/ul-1974

      I am not currently in this business (repurposing batteries) so haven't bought and read the 41 page UL document, but it's out there. Perhaps in the near future, we'll see UL rated Repurposed EV Batteries on Ebay. Time will tell, but there sure will be a ton of batteries available over the next decade compared to the last. Companies are forming in this space to address the (mostly future) market.

      It goes without saying, but this business (ESS) is a new industry using new technologies, so in the big picture we should expect growing pains.

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