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  • First charge winston

    Can someone explain WHY we have to charge to full before usage?
    Can I recharge to 3,45 all of them instead?
    I order 20 winston 1000Ah for my new house project, they should be here in 2 weeks...


    Thx guys

  • #2
    Assuming you have more than 1 cell, they have to be balanced either at the Top or Bottom before first use. When you receive then you have no idea what SOC they are in and they are all over the place and need Balanced before first use. . When you get them connect them all in parallel and walk away for a day. That is it. Then you can either completely discharge them to 2.5 vpc with your Power Labs 8, or fully charge them. Take your pick. Then assemble them in series when you are done.
    MSEE, PE

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    • #3
      What is the charging voltage?

      Comment


      • #4
        Originally posted by Barba View Post
        What is the charging voltage?
        My crystal ball says you are going to be unhappy. You need to have some basic electrical knowledge before you start buying or touching any electrical gear. Then you will know what questions to ask. You are entering into dangerous things, with wires, sparks and flames.
        Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
        || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
        || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

        solar: http://tinyurl.com/LMR-Solar
        gen: http://tinyurl.com/LMR-Lister

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        • #5
          Originally posted by Barba View Post
          Can someone explain WHY we have to charge to full before usage?
          Can I recharge to 3,45 all of them instead?
          Yes, provided you let them absorb down to C/20 and stop. Or if under C/20, there is no absorb since you are already at or below the absorb rate to start with - just stop when you reach 3.45v. Expect some walking around for the first few cycles as the sei layer really settles down. This is far better than taking it up to 4v once, and risking overcharge.

          Initially it was thought that the end-user is going to perform a "forming charge" by doing this. And to some extent that is true for the very first few cycles, but there is no need to do so at 4v. That is just the high end of the lab-spec. AND, unless you hit them with 0.3 to 0.5C in the first place, you may have a hard time getting to 4v, unless one just overcharges them with extremely lengthy exposure, and the voltage finally rises due to electrolyte heating, and not charging!

          It is basically warning to the unknowledgeable end user to charge their batteries first, since many have no idea about the storage / shipping requirements at 50% DOD, and then trying to use up all the capacity they paid for on the first cycle. Without an lvc, that results in trashed batteries.

          From a lab perspective, taking it up to 4v at least once just proves the battery can meet that high-end lab spec, and may flesh out those that can't. Not that this is ideal in normal use.

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          • #6
            Note - from a historical standpoint, this initial value was 4.2v, and lead some to the false conclusion that this was the "nominal" voltage like non-lifepo4 was, and suffered immediate damage treating them from the wrong chemical standpoint.

            The value was quickly changed down to 4v, although stale references on the net may still be found in certain decrepid faqs.

            The point is you can try to meet the lab spec right off the bat, or just take it a bit easier from the start and expect a little bit of sei wandering so to speak for the first few cycles.

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            • #7
              Originally posted by Barba View Post
              Can someone explain WHY we have to charge to full before usage?
              Can I recharge to 3,45 all of them instead?
              I order 20 winston 1000Ah for my new house project, they should be here in 2 weeks...


              Thx guys
              The factory recommends this when top balancing the pack. I had this done to my 4 1000AH Winston's. So far, after about 2 weeks conservative charge and use cycles everything is working fine. One cell tends to go up about .01v above the others under charge, but relaxes back to balance.

              With 20 you probably need to make sure they are well balanced to start with and make sure your monitoring is up to scratch.

              What voltage are you going to run?

              It pays to do the research, although some of it is a bit contradictory.

              I hope you will be as happy as I am with them so far. (early days)

              Comment


              • #8
                Dear Mike thx for the info but if I don't try I will never know, thx to God my bank account sees 6 figures in it so I have room to play with...

                I am already running now (since 4 days)20 cells 700Ah winston max charge in normal ops is 68 V so 3,4 V per cell and stop recharging when current drops down to 0,1 C. This my 100 relative SOC and I count down from here 80%.
                My previous pack was 16 cells 300 ah with 3,45 final voltage with final current 0,25C.
                I install an air conditioning which keeps automatically the temperature at 75F. All year around.

                I am building an house with a daily consumption of 25kWh at the maximum .from my two sun trackers power is in total of 14kw.
                Today is raining and the sky is overcast and I still pump 26 A an hour into my battery...
                I will follow pnjunction advice and then let you know how it goes....

                Comment


                • #9
                  Barba - I think you'll be ok. Just run them up to 95% or so for a few cycles and see how it goes.

                  When guys order that many cells however, some like to have a spare or two onhand.

                  You may also be interested in a service that batteryspace.com provides to those who are willing to pay - UN 38.3 testing services. Perhaps you'd want to see what their lab turns up on one of your old or new cells. THAT would be very interesting indeed.

                  Comment


                  • #10
                    Dear pnjunction,
                    Thx for the info!

                    I will get in touch with them.
                    Just for the record,
                    My previous bank was cycled to 80% around 50 times and 16234 microcycle between 20 and 100 SOC( 100% relative soc as described earlier).
                    I calculated the capacity before removing the bank was beyond the 300 ah which I didn't want to exceed.
                    The age of the bank is 4 years and the temperature for 2 month in the summer was 88 F.
                    I can say at the moment the bank is the same as new.

                    Comment


                    • #11
                      Originally posted by Barba View Post
                      The age of the bank is 4 years and the temperature for 2 month in the summer was 88 F.
                      I can say at the moment the bank is the same as new.
                      That is very encouraging!

                      One thing to remember though is our relatively low-current, psoc style of operations. If we subjected that bank to EV like load-testing with huge current, it may or may not pass.

                      But that's the crux of the issue - our "Sub-C" style of operations is supposed to exceed the nominal specs that these cells were designed to do in the first place - drive high-current amateur EV's for the most part.

                      A touch of conservatism, along with our sub-c operations -provided we keep an eye on the parasitic clock to prevent things from taking TOO long at the ends of the curves - should pay off.

                      Comment


                      • #12
                        Originally posted by Barba View Post
                        Dear pnjunction,
                        Thx for the info!

                        I will get in touch with them.
                        Just for the record,
                        My previous bank was cycled to 80% around 50 times and 16234 microcycle between 20 and 100 SOC( 100% relative soc as described earlier).
                        I calculated the capacity before removing the bank was beyond the 300 ah which I didn't want to exceed.
                        The age of the bank is 4 years and the temperature for 2 month in the summer was 88 F.
                        I can say at the moment the bank is the same as new.
                        With that sort of experience we should probably be getting advice from you.
                        Did you have these top balanced? Charged up fully? Sounds like if you do the same it will be fine.

                        Comment


                        • #13
                          Sorry guys I just noticed a typo ,
                          The full cycles were 500 to 80% DOD and the rest is correct!
                          Hello bunga,
                          Yes they were balanced the first time to 3,799992 V and kept in parallel for about 45 days before usage
                          I don't feel to give any advice here as I am still learning with the help of the forum but whatever I did worked for me so far...
                          I have to say that using 80% of the capacity really doesn't touch the balance of the battery at all if you are between the 10-90 SOC.
                          I do have a active balancer but since I changed the SOC I work with in my last cycles were not affected by active balancing of the bms. I feel to advice not to buy an expensive bms if u plan to use the battery within 70-80%.
                          I have already changed my 100 % SOC to 3,3995 V with current 0.05 C cut,from here I count 80% down.

                          I suspect Pnjuction is right when he says we work with fraction of C.
                          My previous bank always worked at a max of 0,25 C either in charge and discharge which was half of the specs of winston.
                          I truly believe high current damages the battery A lot.
                          When I see in the ev forum people use 8-10 C and go down to 2,6/2,7 volts I feel sorry for those cells.
                          I don't think they will go very far....

                          Comment


                          • #14
                            Barb Lithium cells do not need to be fully charged and cycles. That is a left over from old days. What they do need is to have their capacity or SOC equalized. When you receive them SOC is all over the place. They are not like lead acid batteries where all you have to do is string them together and put an EQ charge to them for 24 hours and life is good and Equalized. When you put them into service you must choose a management strategy of either Top Balance or Bottom Balance. ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Regardless if you use Top or Bottom balance the very first thing you must do is connect all cells in PARALLEL. Then use your Power Lab 8 to either discharge them to 2.5 volts and let them set for a day until open circuit voltage = 2.5 volts. Or charge them to 3.4 vpc and let them set for a day. Once balanced at the Top or Bottom, disassemble and reconnect them in series, and you are ready to go.
                            MSEE, PE

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                            • #15
                              Originally posted by Barba View Post
                              I have already changed my 100 % SOC to 3,3995 V with current 0.05 C cut,from here I count 80% down.
                              Right - but just for the notebook, 3.45v per cell at .05C charge is the canonical 100% value. Obviously you / we are being conservative at the top end.

                              On a similar KISS note, I don't know what you are using to actually determine your 80% discharge value - perhaps coulomb counting. If it is not precise, you may end up taking your cells lower than you want to. In this case our "Sub-C" usage gives us plenty of room with just voltage alone, along the lines of 3.19v per cell to be near 80% *rated* capacity.

                              We all dislike using voltage as a precise determinator, as we know it is more or less just a guide, but in a sub-c application, where no cell is diving like a bat out of hell to the very bottom, 3.19v is easy to spot and catch in time. For me, a "dead man" lvc as a backup to the normal 3.195v limit, is just 3.0v per cell.

                              Those that somehow go below 3.0v per cell, and catch it in time, are advised to come back out of it SLOWLY until you reach 3.2v again. That would be about C/50 max.

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