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SAFE(r) LFP project seen

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  • SAFE(r) LFP project seen

    This looks interesting, and some safety aspects really caught my eye.

    Essentially a 12v / 60 or 100ah 4S LFP project. The big thing to me that might help success is the casing and support for these aluminum-can cells. I'm not so much turned on by the "air" spacing, but moreso the physical spacing between the cells because you REALLY don't want skinned aluminum cases touching each other!

    https://www.youtube.com/watch?v=buNxclZixuU

    Hey, at least this guy is wearing glasses. He's moving too fast for my tastes, and should leave the glasses on a bit longer.

    They appear to be made from these EV cells in either 60 or 100ah

    https://www.electriccarpartscompany....ncased-Battery

    SAFETY is what caught my eye for a DIY'er. Despite the case providing some real protection, PLEASE people, insulate, plasti-dip, or do whatever to cover everything but the head of the tool. But at least when all is said and done, the terminals seem well protected, and cell casing bolted together to avoid side-torque issues from just running a single strip of kapton tape around the whole thing.

    Personally, I'd *clean* the links prior to assembly. But it is nice to see hardware that will allow the standard diy'er to get a proper torque on these things without damaging the cells in the process.

    So the choice is yours - add a bms for protection and passive balancing. Or in my case, YOU are the bms (costly if you blow it!). Or in the case of a wheelchair user, use *active* balancing on charge, say with a Revolectrix PL8 and some LFP specific software - go to wheelchairdriver . com for more information.

    To me, this is a FAR better solution if one is going to DIY, than grabbing a bunch of random junk off the net. I cannot vouch for the quality of the cells, nor do I have any business with these EV guys, but the engineering seen in the casing really turns me on from a SAFETY aspect.

  • #2
    That is about $400/kWh plus the cost of a BMS and parts. Compare the to the Battle Born at $800/kWr or more for the Trojan LFP alternative.
    9 kW solar. Driving EVs since 2012

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    • #3
      One crucial thing that guy seems to miss when putting prismatics together with links is the importance of making sure that the mating sides of the dissimilar metals are clean, and a very thin coating of No-Alox, or PeneTrox or something similar is applied. Oxidation from air exposure, especially on dissimilar metals gets ugly in a few years. And that means varying terminal resistance, which is not healthy - even if you think you've cranked down to an air-tight torque. It's not air-tight.

      Saving costs is pretty cool, but of course now YOU are the component and system tester. And dealing with varying warrantee's. You are placing your sole trust in the prismatic manufacturer that all internal flat-pack cells are matched - no way to measure those on your own like a cylindrical.

      So yes, pros and cons. Just means one has to know what they are comfortable with and what their skill level is. Sometimes just bolting stuff together works, and other times using a proven manufacturer-tested system with a single warrantee might be worth it.

      I might mention that these EV cells seem to be more on the "energy" dense side, as compared to the deep-cycle "power" density side. That is, even with costs cut like this, does a fractional-C solar system really need a 6C intermittent current draw capability? Are you paying for that capability you'll never use in our application? Yes, but other factors may make up for it.

      In other words, for those familiar with smaller LFP cells, using an energy dense LFP like a Headway to power your walkway solar garden lights is total overkill. Likewise using power-type lfp's to start your car is, um, a non-starter unless you totally go overboard in capacity.

      Just some battery nerd rambling here....

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      • #4
        Originally posted by PNjunction View Post
        One crucial thing that guy seems to miss when putting prismatics together with links is the importance of making sure that the mating sides of the dissimilar metals are clean, and a very thin coating of No-Alox, or PeneTrox or something similar is applied. Oxidation from air exposure, especially on dissimilar metals gets ugly in a few years. And that means varying terminal resistance, which is not healthy - even if you think you've cranked down to an air-tight torque. It's not air-tight.

        ..........
        I have found No-Alox to readily available and it does a great job.
        9 kW solar. Driving EVs since 2012

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