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LifePO4 Cells

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  • #16
    Thanks for the feedback guys. I am going to try my simple cap dump idea since I have everything at hand to do that.

    Did Mr. Bedini ever release details on building the regulator? I see teslagenx sells them but man I cannot see spending that much on one. What I don't get is what does he do with the surplus of energy once the backside has reached the 15v or wherever he sets it? The wheel is feeding in gen mode which is pretty strong to begin with so when the back is no longer taking it what the heck is he doing with it? Maybe he just has a heavy ceramic resistor to bleed it off? I'm not familiar with the circuit so any clarification would be appreciated.

    I will start fiddling around with the cap dump method and report back if it's worth mentioning.

    Comment


    • #17
      Posting a short video of what I have found out so far. In short I do think the low voltage cap dump will work. I will have to continue testing and especially to see if the battery still performs well after many cycles but I think it will.

      Video:
      https://1drv.ms/v/s!AmzmftzD-V0miGZfnsik0HUJYgdA

      Comment


      • #18
        Hi Bob nice video. In my cap dump runs with LiFePo4, they always charged ok, and performed ok when discharged. I didn't have the problem you have because my lifepo4s are single cell small batteries. Now days I am running tests with common ground without diode and solid state without cap dump. My batteries are in bad shape, they are giving me like 70% of the rated amps hours. Will see if lifepo4s also gets rejuvenated...

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        • #19
          Hey guys,
          I went ahead and did a full test run using the low voltage cap approach, same thing as the last short video but a full run to see if it would truly work.

          It did work pretty good but took a long time. I'm not sure I could tolerate doing this on a regular basis. This was just a small 20AH pack and I have much larger to consider. It as a good experiment though. I can charge the same pack with the lifepo4 charger and an inverter in about 3 hours because it is a 10A charger.

          Here is a chart:
          LifePO4_lowPower_capDump.JPG

          And a video of the run:
          https://1drv.ms/v/s!AmzmftzD-V0miGesUAd2Y-c_ZnTh

          Comment


          • #20
            Hey Bob, that was a pretty good run. Even though it did take a while. You'll see a lot better charging if you fatten up and shorten the wires between the caps and the charge battery.

            I know it was an experimental test run, but I also would've run the SS SG a bit harder - around about 1A draw.

            Thanks for sharing.

            John K.

            Comment


            • #21
              Originally posted by John_Koorn View Post
              Hey Bob, that was a pretty good run. Even though it did take a while. You'll see a lot better charging if you fatten up and shorten the wires between the caps and the charge battery.

              I know it was an experimental test run, but I also would've run the SS SG a bit harder - around about 1A draw.

              Thanks for sharing.



              John K.

              John I had to run so low because of what I was trying to achieve with the low voltage cap dump. The issue is that once the battery is full I need the bleeders to pull off excess to maintain the 14.6 voltage. If I crank up the front then they cannot keep up and the voltage rises too high at the end. I described it a few posts back but I know it's not as clear in your thought as it is mine since your not working on it. I can charge them very fast relative to this run if I want but I have to catch it at exactly the right time and turn it off or they go way high at the end which is really bad for LifePO4. It's really just a matter of having a bleeder on the back that could drain off however much current I push once the top voltage is reached. I am trying to make it so that at no point in time the voltage those cells goes over 14.8 or so.

              I have thought about taking a zener diode and putting on the gate of a FET with the drain and source connected to the battery with a light bulb between. Put the zener to the pos and when the voltage is reached to pass through it then the fet closes and the light burns off the extra. Basically the same as the small bleeders do but across the whole battery. If I could get something like that working then I could increase the draw to as much as the bulb could keep up with.

              I have kind of set this aside for now since I am building the new 3D project and my commercial lifePO4 charger works fine.

              Comment


              • #22
                Originally posted by BobZilla View Post
                John I had to run so low because of what I was trying to achieve with the low voltage cap dump. The issue is that once the battery is full I need the bleeders to pull off excess to maintain the 14.6 voltage. If I crank up the front then they cannot keep up and the voltage rises too high at the end. I described it a few posts back but I know it's not as clear in your thought as it is mine since your not working on it. I can charge them very fast relative to this run if I want but I have to catch it at exactly the right time and turn it off or they go way high at the end which is really bad for LifePO4. It's really just a matter of having a bleeder on the back that could drain off however much current I push once the top voltage is reached. I am trying to make it so that at no point in time the voltage those cells goes over 14.8 or so.

                I have thought about taking a zener diode and putting on the gate of a FET with the drain and source connected to the battery with a light bulb between. Put the zener to the pos and when the voltage is reached to pass through it then the fet closes and the light burns off the extra. Basically the same as the small bleeders do but across the whole battery. If I could get something like that working then I could increase the draw to as much as the bulb could keep up with.

                I have kind of set this aside for now since I am building the new 3D project and my commercial lifePO4 charger works fine.
                why not try the "linear current amplifier" link I sent you a couple weeks ago... check ur PM's anyone can search and find...

                Comment


                • #23
                  Patrick I never got any message from you.

                  Comment


                  • #24
                    Originally posted by BobZilla View Post
                    Patrick I never got any message from you.
                    get it while it lasts:
                    https://www.youtube.com/watch?v=WswpE6DUSG0
                    anything i've posted like this on this sight gets taken down fairly quickly.

                    Comment


                    • #25
                      Originally posted by min2oly View Post
                      why not try the "linear current amplifier" link I sent you a couple weeks ago... check ur PM's anyone can search and find...
                      Great idea Patrick. I watched the video you posted. I'm not sure how close that guy is to Bedini's circuit but it does look pretty effective.

                      John K.

                      Comment


                      • #26
                        I appreciate your sharing that video and it is interesting for sure.

                        A few things I want to mention however. I did watch that video and the other part three that guy had. In part three he gets the dials working and had some LED's showing his voltage control. That's good but it leaves a lot of the problem on the table.

                        As I said in my first comment about Mr. Bedini's video, what does he do with the surplus energy when the voltage has been reached. This guy in the video is feeding his circuit at least in the part 3 with a battery, we all know a battery will only give what the load asks for but hooking up a running SSG is quite a different beast. That energy is going to come and keep coming no matter what and you must do something with it of it will destroy itself. Think what happens if you disconnect a charge battery while running or hook up a shorted battery.

                        Well automagically switching off the charge battery would be the same result. The problem boils down to the same thing I am already looking at and that is burning of excess energy once charged (unless your there to stop it). I did not do the run in my video on extremely low settings because I could not control the voltage, I can run very high and have the same voltage control with timing adjustments, I ran low because of the finishing phase.

                        It is not totally about the last cut off voltage though. If it were then I could cap dump or run normal mode one until reaching 14.6 and cut off if I had the way, but no this is about never showing the anode more than 14.6v, in other words dampening the spike before it gets to the LifePO4 chemistry. That is why I am buffering with that cap and not just running full on to the battery.

                        Comment


                        • #27
                          http://www.ebikeschool.com/how-to-bu...m-18650-cells/
                          seemed relevant.
                          Cant spend it when your dead.

                          Comment


                          • #28
                            I have made some 3D printed frames for the LifePO4 cylinder cells. Below you can see a 44AH pack I am working on. It was made from four 16 cell trays that I printed up. I have made single, 4, 8 and 16 cell files both with and without tabs for joining together and making custom size packs. The cells are held in with a little 2 part epoxy and I am going to wrap and tape the whole thing as before. I like this design better than just gluing the cells all together as I did before.

                            I am not posting the files just yet because I still need to finish this one. I need to make a few pieces for mounting studs and get this one all finished up and then I will share the files if anyone is interested using them.

                            BZ-3D-LFP-1.jpg

                            BZ-3D-LFP-2.jpg

                            I made this little 6v pack to experiment with. I actually made two of them and I am going to take at least one of them and charge it only from one of my machines and see how it holds up.

                            BZ-3D-LFP-2Cell.jpg

                            More on this new big pack later. I am waiting on the studs and bolts to arrive for making terminals for it. I wanted this one to have standard posts instead of the Anderson plugs I used before.

                            Comment


                            • #29
                              Nice build Bob!! will be interesting to see what it looks like completer!!

                              Tom C


                              Originally posted by BobZilla View Post
                              I have made some 3D printed frames for the LifePO4 cylinder cells. Below you can see a 44AH pack I am working on. It was made from four 16 cell trays that I printed up. I have made single, 4, 8 and 16 cell files both with and without tabs for joining together and making custom size packs. The cells are held in with a little 2 part epoxy and I am going to wrap and tape the whole thing as before. I like this design better than just gluing the cells all together as I did before.

                              I am not posting the files just yet because I still need to finish this one. I need to make a few pieces for mounting studs and get this one all finished up and then I will share the files if anyone is interested using them.





                              I made this little 6v pack to experiment with. I actually made two of them and I am going to take at least one of them and charge it only from one of my machines and see how it holds up.



                              More on this new big pack later. I am waiting on the studs and bolts to arrive for making terminals for it. I wanted this one to have standard posts instead of the Anderson plugs I used before.


                              experimental Kits, chargers and solar trackers

                              Comment


                              • #30
                                Thanks Tom, Yea I am excited about this project.

                                I have wasted a lot of filament making mistakes but I am getting to the finished product now. I decided to make a side plate that will get glued on to cover the buss bars. I am leaning towards not wrapping it up with tape or foam now, it's just too nice to cover up like that

                                I discovered something awesome tonight with my printer. I never really played too much with the layer height before but I decided to give .35 a try and it is great for these larger parts. I can get these things printed SO much faster now and really they are just as good quality because of the simple boxy nature of these parts.

                                By the way guys I am using maker geeks recycled filament line and it is really nice for what it is. You cannot choose a color because it is made from scraps but last time I ordered some I got 4 rolls and they were a nice black. Anyway the stuff is worth checking out if color isn't important to you because it's good quality material and only $15 a kg. I have not had any issues like clogging or boogers on the nozzle.

                                Here is a view from fusion of the parts. This is of course a cut away so you have to imagine the missing pieces with the cells installed.

                                BZ-3D-LFP-fusion-1.JPG

                                BZ-3D-LFP-fusion-2.JPG

                                I got the posts I was waiting on but realized I was going to need some washers and ring terminals so I'm waiting on another order now to finish building the large pack.

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