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LifePO4 Cells

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  • #31
    Very nice project, i agree with you about not wrapping them, it'll look great as it is.


    • #32
      Hello Group,

      I finished my prototype build of the 44AH LifePO4 pack. I think it turned out great. I have not had time to post the files yet but I will try to get them posted soon if anyone wants to use them.

      So I used the anderson plugs on the ends for connecting the charge bleeder boards. These are the same ones I used on the earlier packs (red ones) from this post. Those boards are a little expensive so I have designed all of my packs to use the same ones and I can just move them around when charging, you do not need them attached when running loads. So that is what you see coming off the sides in the picture below. I used some auto battery side bolt to post converters to make posts on the top and fastened a ring terminal between a brass washer and the post to make the connection. One of the big features of this pack vs the original red ones I made is that each cell is suspended in it's own place so they are not just all glues together. There are vent holes all around to let heat escape, although I usually don't run them hard enough for heat to be a problem it's still a much smarter design this way.

      Here is a picture with it all wired up before I put the outer covers on.

      And here is the finished battery.

      I am charging it up right now but I will try post a discharge curve in a few days to see how it performs.


      • #33
        Nice, very nice.
        Thank you for sharing.


        • #34
          Thank you for sharing.


          • #35
            Originally posted by BobZilla View Post
            Hello Group,

            Today I am showing this LifePO4 pack being used in bedini tech. Faraday didn't elaborate much with his statement but I think what he was trying to say is the same as I will say here now. Lithium batteries make awesome primaries for many reasons. One of the biggest reasons is that you get almost no voltage drop across a run. You can see this in the chart below. This run was approximately 28 hours at 1A and the primary hardly sagged at all.

            The run was done on a SSR solid state mode one type of circuit. On the front we have the battery that this thread is about and on the back we had two garden batteries in series. These garden batteries were very depleted although you would not know it looking at their starting voltage. These batteries always bounce back up to a fairly high voltage no matter where I drag them down too, I think in part because of the radient charging they have received. I did not mention it in the video but I had actually run these down to about 9v by accident the night before with them as a primary in parallel. They had bounced back to around 12.2 from that and that is where they got setup for this charge.

            Anyway here are the charts:



            And a short video of the beginning and end of the run.

            Hi Bob,
            Here is what I wanted to emphasis.. we know that a SSG does a Positive Radiant effect on the Primary battery and does a Negative Radiant effect on the secondary battery...different chemistries are friendly to each type of the Radiant effects. so having LPF on the primaries are friendly here while the lead-acid are friendly at the secondary.. as a rule of of the thumb..batteries whoes chemistry permitt the discharge to almost zero..are suitable as the primaries..while those that are considered dead at 80% or below of their full capacity Voltage like the Li-ion or Lead -acid can be made the secondary batteries.. thats gist..this is chemistry regauging..
            'Wisdom comes from living out of the knowledge.'


            • #36
              Hello group,

              I have a few pictures of a prototype battery box using the LFP cells. On this particular one I was having issues with my printer when I printed the bottom half but it came out usable so I went ahead with building it. The next one will look better. What this has is 4 LFP cells in series with two 12v jacks on the front to connect standard 2.1mm dc jacks to. I didn't need posts on this small one but larger ones I will add them. The other jacks across the top are connected across each cell for balance boards. For larger packs I will just build backwards on the rows in parallel with the first of each.

              I have been running my medium size machine on it quite well which pulls about 700ma. I also have done away with the power pole plugs for connecting the bleeders that I used on the models before this one and am using male to male adapters and jacks which are so much nicer. I printed little boxes for the bleeder boards to hide the wiring and protect them.

              Anyway I just thought I would share some pics of this little battery made from LFP cells.

              BZ-LFP 4CBox.jpg

              Here is is with the lid off.
              BZ-LFP 4CBox-2.jpg

              And a transparent mechanical drawing so you can see better what we are looking at
              BZ-LFP 4CBox - angle.JPG


              • #37
                Nice work Bob.


                • #38
                  Thanks Brian I appreciate that.

                  I have uploaded the files for anyone that wants to build this style of pack, there is a builder note that lists parts.

                  I will be making larger versions and making them available a bit later. This one was only a 4 cell but it was a test to see how well the new bleeder board system would work and if the desighn over all was good. Now it's just a matter of adding rows to make them larger.

                  The files can be found at the following link along with the other things I have shared with the group: