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    Each battery can have its own bms that is not an issue, I was simply saying there was no need to buy anymore bms you could use the 7s bms you already have. The pack you took apart was 7s. The picture above with the cells in the green case looks like 4s8p. That means what you have left over should be 3s8p.
    Lifepo4 cells are 3.2v nominal so you would need 8s to make 24v pack. Lithium or NMC cells are 3.7v nominal so you only need 7s for 24v.

    I will draw you a diagram tomorrow when I have more time.

    Comment


      I drew your battery in cad but had to draw the wires in paint so it is not the prettiest.

      Drawing of your battery after cutting the back off to make it 7s8p.
      Click image for larger version

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      After splitting the battery into a 3s and 4s. Leave all the bms and balance wires connected, move bms along the 3s side so it will fit in the box. Add a heavy jumper wire from the positive 3s to the negative 4s bridging the tin strips you cut when you split the battery. You will essentially have the same battery you started with but now you have a gap between the 3rd and 4th series connection .
      Click image for larger version  Name:	7s split wires.JPG Views:	0 Size:	167.9 KB ID:	2908218

      You will have a negative wire coming out of one box and a +24v wire coming out the other box. You will also have the jumper and some balance wires crossing between the two. Having two jumper wires, one on each end would be better, but if you use one I would put it in the middle between the 4p and 5p cells, not like I have it drawn on one end.
      Attached Files

      Comment


        Yes ! thanks Maddog for you diagram and your help.
        The battery is now, more or less, totally dismantled, so we have some options I would like to share with you, feel free to give me your ideas. Of course now as we have made some mistakes and separate most of the cells, the BMS and so…, we have lost some advantages there was in one or the other option (!)
        - The last one, I think, is the worse (?). As a total newbie in the electric world, I forgot Li-Ion cells were 3,7V. As we were happy to see we could put 32 cells in each green enclosure -from a previous mistake- I bought 2 new BMS 4s, to make 2 batts 4s8p… BUT now I realize 4x3,7 = 14,8V each, so I'm going to have my ZX-1working under 29,6V instead of 24. Maybe it can do the trick (I think the controller may have a little margin) or maybe not… What do you think of it ? Is there an advantage somewhere? Anyway, even if I've already bought these BMS, they are not expensive and it doesn't matter if I don't use them.
        - the other solution (your solution) is easy, safe, and inexpensive, as it uses most of the parts I already have. It's the best choice for sure. But my buddy, who is going to solder it, doesn't like the idea of wires crossing between the boxes. I don't know why exactly, I think we have to figure out together how to make it as clean as possible.
        - last option, not sure it is doable… It is trying to use all the cells we have (if possible) cutting the batt "only" in 4s/3s and keeping all the 10p. This way, we could have 24A and it's a nice implementation. We'll see if the boxes we have can be modified a little bit.
        C6-7 since mid 2002, no hand control nor triceps.
        my website & my job (in France): Accessibility advisor www.acceslibre.eu
        Also working on a French research about Peer counseling and Empowerment.

        Comment


          3.7v is nominal, the total range is 4.2v full charge to around 2.5v-3.0v empty depending on what the bms is set to. At 8s full charge is 33.6v, too high for me to feel comfortable using. You can buy a 3s bms and continue like you were doing and have a 3s with bms plus a 4s with bms instead of two 4s plus bms. That configuration will still look very similar to the one pictured above except without the balance wires crossing over. The positive of one box will have to cross over to the negative of the other box to connect the two in series to get 24v total. You will have a heavy wire crossing from one box to the other no matter what.

          Comment


            Ok thanks Maddog. I think we are going to try 4s10p/3s10p if possible. If not, 4s8p/3s8p. We'll see.
            C6-7 since mid 2002, no hand control nor triceps.
            my website & my job (in France): Accessibility advisor www.acceslibre.eu
            Also working on a French research about Peer counseling and Empowerment.

            Comment


              Bigger is always better, if 10p will fit go for it. If you are starting over and any configuration is on the table you might also think about 7s4p on each side and run them in parallel, have two 24v batteries.

              Comment


                OK, I have most of the parts ordered on the table now. So, as you said it Maddog, we are starting over, what is for you the best choice ? We have 70 Li-ion cells, 2 enclosures that can accept 32 elements and their BMS, one 7s BMS, two 4s BMS (mistake here) … and enough soldering tape and thermo-retractable cover. I think with a bit of work on the enclosures, they can go to 36 cells. I can also buy more (!) BMS, they are affordable.
                What is the best to do ?
                - ONE battery in two pieces, 4s10p/3s10p, 24v 26A
                - TWO batteries 12v serial, 4s8p
                - TWO batteries parallel, 24v each, 7s4p
                ? ?
                C6-7 since mid 2002, no hand control nor triceps.
                my website & my job (in France): Accessibility advisor www.acceslibre.eu
                Also working on a French research about Peer counseling and Empowerment.

                Comment


                  Any of them should work but I would go with one 24v battery. It is the simplest with the least number of bms's causing less issues. Charging the 2 battery system should not be a problem but you know it won't be with the 1 battery. 2 batteries in serial is my least favorite although I can't give a good reason why.

                  Comment


                  • robotnik
                    robotnik commented
                    Editing a comment
                    We'll go for one 24v then.

                  • robotnik
                    robotnik commented
                    Editing a comment
                    ok thanks !

                  Be careful and make sure the balance wires are connected correctly. I would pull the balance plug from the bms before connecting them to the battery and then check them with a multimeter before plugging them back in. Here is a video I found showing what to do. At the 2:51s mark is how you need to test. Be careful when testing the first two because the multimeter probes will be very close to each other and could short out.

                  Also if you are building it like my cad drawing above you can turn the 4s side over when done and have both heavy wires pointing up. This makes it more important to check the balance wires as things can get confusing when half the battery is upside down.

                  Comment


                    The lithium ion option is discontinued for the ZX one. Has anybody had any luck finding the identical lithium ion batteries that came in there ZX
                    My batteries are starting to fade a bit and I'd like to have a back up set
                    Bike-on.com rep
                    John@bike-on.com
                    c4/5 inc funtioning c6. 28 yrs post.
                    sponsored handcycle racer

                    Comment


                      Sorry to hear they discontinued the batteries Fuentes cause I was about to order a set thru you.
                      Last edited by Patrick Madsen; 15 Apr 2021, 2:11 AM.

                      Comment


                        Originally posted by Patrick Madsen View Post
                        Sorry to hear they discontinued the batteries Fuentes cause I was about to order a set thru you.
                        Yeah major supply chain issues with batteries from China
                        Bike-on.com rep
                        John@bike-on.com
                        c4/5 inc funtioning c6. 28 yrs post.
                        sponsored handcycle racer

                        Comment


                          John, a few months ago there were nice Bioenno LiFePo4 batteries available at WheelchairScooterParts. They were OK for spare on the ZX-1, very affordable (about 150$ each) Are they out of stock too ?
                          C6-7 since mid 2002, no hand control nor triceps.
                          my website & my job (in France): Accessibility advisor www.acceslibre.eu
                          Also working on a French research about Peer counseling and Empowerment.

                          Comment


                            Originally posted by robotnik View Post
                            John, a few months ago there were nice Bioenno LiFePo4 batteries available at WheelchairScooterParts. They were OK for spare on the ZX-1, very affordable (about 150$ each) Are they out of stock too ?
                            I actually found two of the exact same batteries that spinnergy was using
                            they had sent me a link to the battery and it showed out of stock I reached out to the supplier and they were able to open it up and let me order two of them 199 each
                            Bike-on.com rep
                            John@bike-on.com
                            c4/5 inc funtioning c6. 28 yrs post.
                            sponsored handcycle racer

                            Comment

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