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Li-ion vs LiFePo batteries

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  • #16
    Doing more research it seems that building your own pack is the best bet. I guess I've been dabbling in the cheap end of LiFePO4.
    Specs on the above cell is awesome. I bet it would be a killer 8S3P config! How do you locate a BMS that would fit such a killer cell?

    26650 size is the same as the K2 pack which fits nice under the deck. Dakota cell is 9A, K2 cell is 12A discharge where A123 is 50A.
    Last edited by ESR_RSE; 08-02-2019, 06:18 PM.


    • #17
      Interesting that the battery space site shows A123 26650 cells from A123 Systems when their website only shows pouch style batteries in that chemistry. I have what I thought was an A123 38120 pack but now those cells show up as Headway 38120S 10Ah 10C LiFePO4 Cylindrical Battery Cells. The pack is built as an 8S2P split into two packs (one in each "well" with the BMS sitting in the center). The 26650 looks to be significantly smaller with apparently the same specs.


      • #18
        Weird. I would think that each pack would need it's own BMS. But I guess as long as the BMS can handle the split pack but I would think that could lead to more cell based errors in balancing.

        I would really dig having a set of LiFePO4 packs in 8SP3. Only 15Ah capacity but something like 300A current instant.
        Last edited by ESR_RSE; 08-12-2019, 11:00 AM.


        • #19
          I believe this is the BMS used with my battery pack. As I recall it cycles through each 8 cell series pack “A1-8” and switches to the second one “B1-8” or something like that. I’d need to look at it again to be sure. Each 8 cell pack has a ground and power lead coming off it.

          3S ~ 8S LiPo lifePo4 Li-ion 25A 100A BMS Battery Management System Chargery BMS8


          • #20
            Ah thanks for that. Seems in the GoPed YouTube video that has the headway cells pictures that BMS too.

            BTW here are some older threads about making/sourcing replacement Go Ped batteries:


            • #21
              The GoPed video is my exact setup from about when I upgraded. I had one the the first few LiFePo4 upgrades they built. It’s worked well but, as I wrote above, I’m concerned the batteries were hurt when they discharge too much. And I know chemistries and energy densities have advance in the last ten years too.


              • #22
                Originally posted by SoCal Steve View Post
                Would be a nice fit with these cells.


                • #23
                  So I bought a pair of used Go Ped LiFePO4 packs (from a nice member!). Much better than the Dakota or K2 I tested before. These apparently can output a high rate. I did not have the BMS shut down in 5 mi test riding this weekend. I changed the gearing to be kinder to the batteries to 15/75 (was running 15/72) and hit 24 mph.

                  My controller is set to CurrHi 36A/CurrLo 35A and I think acceleration @ 10%. As long as BMS does not trip then this is a big improvement regarding the Tork scooter. The K2 batteries run the 11/80 silver motor fine so far.
                  Last edited by ESR_RSE; 10-10-2019, 03:22 PM.


                  • #24
                    Originally posted by ajetsrgn1 View Post
                    I have a Kweld
                    Hey I just ordered the kWeld from the USA distributor. Really looks like a quality unit for sub $300 for kit w extra spares + case.
                    Last edited by ESR_RSE; 08-15-2019, 02:22 PM.


                    • #25
                      Now you just have to figure out your power source.
                      I didnt want to have to deal with the lipo high discharge packs many people use.
                      I found one at autozone that has threaded terminals with wingnuts. You want the highest cca rating available.


                      • #26
                        Originally posted by ajetsrgn1 View Post
                        Now you just have to figure out your power source.
                        I didnt want to have to deal with the lipo high discharge packs many people use.
                        I found one at autozone that has threaded terminals with wingnuts. You want the highest cca rating available.
                        Ok! Is it safer than the lith ion or why marine?


                        • #27
                          I didnt want to deal with charging the lipo packs or even have them in my house.
                          Lead acid is very safe easy to charge. The main drawback is weight.
                          But it sits on my bench so Im not moving it.
                          If u go lead acid, u definitely want one designed for starting.
                          I went with the marine battery cause of the price and the high CCA.
                          Plus it has a second set of threaded terminals to attach my kweld.


                          • #28
                            So I just got my kWeld supply battery. I went with the lowest resistance one I could find after emailing the kWeld designer.
                            "Yowoo Graphene 3S 11.1V 4000mAh 100C Lipo Battery"

                            Anyone have specs of BMS or cells used in their custom ESR packs?


                            • #29
                              Just ordered A123 LiFePO4 cells, 30A continuous discharge in 18650 form factor. Should make 2x 8s7p packs but need to find a matching BMS.


                              • #30
                                I might cut back open those K2 packs and reweld them into 7S4P.
                                The voltage would drop but could find a different BMS to run 40A since those cells are rated at 12A each continuous. Also the pack would be 12.8Ah