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  • making a battery

    I have purchased 28 Headway 38120hp to build a 12v battery. I'm having a hard time understanding how to and what to use for balancing cells since I read a lot about people balancing cells with setups higher then 12v. I understand the dangers of lithium, which is why I want to understand what I'm doing before I do anything with charging or grouping the batteries. What do you guys use for balancing batteries? And tips on where I should start with this project would be great.

    Link to the datasheet http://www.akkuenergiesysteme.de/app...ifications.pdf


  • #2
    Originally posted by ahdiofreak View Post
    I have purchased 28 Headway 38120hp to build a 12v battery. I'm having a hard time understanding how to and what to use for balancing cells since I read a lot about people balancing cells with setups higher then 12v. I understand the dangers of lithium, which is why I want to understand what I'm doing before I do anything with charging or grouping the batteries. What do you guys use for balancing batteries? And tips on where I should start with this project would be great.
    What are you going to do with it?

    Comment


    • #3
      This is funny stuff.
      MSEE, PE

      Comment


      • #4
        It will be very difficult for anyone to give useful feedback without knowing what you are planning on doing. Having a detailed plan should be the first step before purchasing anything.

        Comment


        • #5
          Originally posted by Sunking View Post
          This is funny stuff.
          Yea, I kind of suspected something like this might happen from reading the OP's first post.

          Comment


          • #6
            Originally posted by J.P.M. View Post

            Yea, I kind of suspected something like this might happen from reading the OP's first post.
            He is a Stoner. Pass the bong please.

            MSEE, PE

            Comment


            • #7
              It is will be used as a battery in my car stereo setup. I got the cells for a good price, so they can be sold easily if im not able to use them since I did purchase them without actually having a plan.

              Comment


              • #8
                I did not know they made class a amps anymore for cars! Did you get a Krell and a inverter?

                Comment


                • #9
                  Gosh the naysayers on this forum...

                  This is pretty simple tbh, and LiFePO4 is basically the safest battery chemistry going, so don't worry so much.

                  You'll need a 4S setup. This'll get you to ~13V. To do that you have two options:

                  1) 7 4S cells in parallel. You'll need to balance all of the cells in series, so you'll need 7 balancers.

                  2) 7 cells in parallel, connected in series 4 times. You'll only need one balancer here, however you'll be trusting the individual cells in each parallel set to balance each other. Truth be told, I wouldn't worry about this in such a cheap pack. You can always pick up replacement cells if you kill any.

                  Balancing's controversial. Plenty of people don't see it as necessary, suggesting you bottom balance the pack instead, charge them until the first cell reaches 'full', and then use these two voltages as your 'top and bottom' thresholds, assuming the batteries will deteriorate more or less in line with each other. You've got a small pack here (about 56Ah) and I'd be inclined to do it like this too. Alternatively, build out the option #2 pack and get a single active balancer (https://www.aliexpress.com/item/3S-t...950876697.html) which will just keep on balancing the pack forever.

                  Alternatively, get a BMS that'll do it for you. If your current draw isn't huge you could do this, but depending on how utterly absurd your audio setup is, this might not be an option.

                  Good luck!

                  Comment


                  • #10
                    Originally posted by phazaar View Post
                    Gosh the naysayers on this forum...

                    This is pretty simple tbh, and LiFePO4 is basically the safest battery chemistry going, so don't worry so much.

                    You'll need a 4S setup. This'll get you to ~13V. To do that you have two options:

                    1) 7 4S cells in parallel. You'll need to balance all of the cells in series, so you'll need 7 balancers.

                    2) 7 cells in parallel, connected in series 4 times. You'll only need one balancer here, however you'll be trusting the individual cells in each parallel set to balance each other. Truth be told, I wouldn't worry about this in such a cheap pack. You can always pick up replacement cells if you kill any.

                    Balancing's controversial. Plenty of people don't see it as necessary, suggesting you bottom balance the pack instead, charge them until the first cell reaches 'full', and then use these two voltages as your 'top and bottom' thresholds, assuming the batteries will deteriorate more or less in line with each other. You've got a small pack here (about 56Ah) and I'd be inclined to do it like this too. Alternatively, build out the option #2 pack and get a single active balancer (https://www.aliexpress.com/item/3S-t...950876697.html) which will just keep on balancing the pack forever.

                    Alternatively, get a BMS that'll do it for you. If your current draw isn't huge you could do this, but depending on how utterly absurd your audio setup is, this might not be an option.

                    Good luck!
                    If someone comes onto this forum with an idea that they have no experience or understanding it is our responsibility to make sure they do not do something that can hurt them or others.

                    Building a battery (any chemistry) from parts without a background in the science can be very dangerous to the novice.

                    One wrong action could cause a fire or an uncontrolled release of energy from a storage component.

                    Comment


                    • #11
                      Originally posted by ahdiofreak View Post
                      It is will be used as a battery in my car stereo setup. I got the cells for a good price, so they can be sold easily if im not able to use them since I did purchase them without actually having a plan.
                      Building a battery is not something you can do without some knowledge and experience. Without that, you risk damaging the cells (best case) and a fire (worst case.) I'd recommend two approaches:

                      1) Find a friend with lots of experience/knowledge and have him build it. You may have to buy him lots of beer and/or pizza.

                      2) Sell the cells and get a battery like the Thundersky that comes built-out as a 12V battery.

                      Comment


                      • #12
                        Originally posted by goodoleme View Post
                        I did not know they made class a amps anymore for cars! Did you get a Krell and a inverter?
                        They make class a/b amps for full range and class D for bass. And bass is what im mostly worried about because it draws the most current. I do not know what a krell is and no I don't have an inverter

                        Comment


                        • #13
                          Originally posted by phazaar View Post
                          Gosh the naysayers on this forum...

                          This is pretty simple tbh, and LiFePO4 is basically the safest battery chemistry going, so don't worry so much.

                          You'll need a 4S setup. This'll get you to ~13V. To do that you have two options:

                          1) 7 4S cells in parallel. You'll need to balance all of the cells in series, so you'll need 7 balancers.

                          2) 7 cells in parallel, connected in series 4 times. You'll only need one balancer here, however you'll be trusting the individual cells in each parallel set to balance each other. Truth be told, I wouldn't worry about this in such a cheap pack. You can always pick up replacement cells if you kill any.

                          Balancing's controversial. Plenty of people don't see it as necessary, suggesting you bottom balance the pack instead, charge them until the first cell reaches 'full', and then use these two voltages as your 'top and bottom' thresholds, assuming the batteries will deteriorate more or less in line with each other. You've got a small pack here (about 56Ah) and I'd be inclined to do it like this too. Alternatively, build out the option #2 pack and get a single active balancer (https://www.aliexpress.com/item/3S-t...950876697.html) which will just keep on balancing the pack forever.

                          Alternatively, get a BMS that'll do it for you. If your current draw isn't huge you could do this, but depending on how utterly absurd your audio setup is, this might not be an option.

                          Good luck!
                          I will look into the active balancer, thanks! Even though these cells are cheap to replace and easy to get at the moment, I don't want to risk damaging any of the cells. At my level of car audio, there can and will be a high amounts of discharge going on rapidly. So a cell or more (especially lithium, have you seen vape batteries explode?) leaking or exploding, in a vehicle is not safe lol It could damage my equipment, or even worse catch my car on fire. A BMS would not do good with car audio, but I do plan on getting some cell logs to monitor each bank so I can see whats happening.

                          Comment


                          • #14
                            Originally posted by jflorey2 View Post
                            Building a battery is not something you can do without some knowledge and experience. Without that, you risk damaging the cells (best case) and a fire (worst case.) I'd recommend two approaches:

                            1) Find a friend with lots of experience/knowledge and have him build it. You may have to buy him lots of beer and/or pizza.

                            2) Sell the cells and get a battery like the Thundersky that comes built-out as a 12V battery.
                            If I had a friend that knew anything, I wouldn't have came here to bother you guys. Trust me. But if I need to leave or have too I will.

                            Comment


                            • #15
                              Originally posted by SunEagle View Post

                              If someone comes onto this forum with an idea that they have no experience or understanding it is our responsibility to make sure they do not do something that can hurt them or others.

                              Building a battery (any chemistry) from parts without a background in the science can be very dangerous to the novice.

                              One wrong action could cause a fire or an uncontrolled release of energy from a storage component.
                              It is my responsibility to learn what I need to know before I start working on any DIY project, and its my own risk. And its my job to make sure I have the proper equipment to do whatever it is safely.

                              Comment

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