Announcement

Collapse
No announcement yet.

Tesla battery pack?

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • #46
    Originally posted by nebster View Post

    There is a ton of user-submitted data from all over the world showing Tesla pack maxranges versus distance driven.

    https://docs.google.com/spreadsheets...Psg/edit#gid=0
    I am not saying that a used Tesla battery can't be installed as a home energy storage unit that will last a long time.

    What I am saying is that the average person or even some that are electrically educated could still have a problem keeping the system going and above all SAFE.

    Comment


    • #47
      Originally posted by SunEagle View Post
      I am not saying that a used Tesla battery can't be installed as a home energy storage unit that will last a long time.

      What I am saying is that the average person or even some that are electrically educated could still have a problem keeping the system going and above all SAFE.
      I was responding to the post by Sunking suggesting that there was no data on Tesla pack longevity.

      Comment


      • #48
        Originally posted by nebster View Post

        I was responding to the post by Sunking suggesting that there was no data on Tesla pack longevity.
        Not doing his thinking for him, but I took SK's post not as that no data existed, but rather that he was questioning the validity of at least some if not a lot of the data.

        Comment


        • #49
          Originally posted by J.P.M. View Post

          Not doing his thinking for him, but I took SK's post not as that no data existed, but rather that he was questioning the validity of at least some if not a lot of the data.
          His words literally say "not one documented case." There are hundreds of documented vehicle packs in that one worksheet.

          Comment


          • #50
            Originally posted by nebster View Post

            His words literally say "not one documented case." There are hundreds of documented vehicle packs in that one worksheet.
            Whatever you say.

            Point is, it's all from one place - a source SK seems to think is questionable, maybe because it may be biased, cherry picked, reinterpreted or just plain B.S. It can also be 100 % true and correct. Without peer review/vetting/verification there's no way to tell.

            Because something is written/printed says nothing of its accuracy or veracity.




            Comment


            • #51
              Originally posted by J.P.M. View Post

              Whatever you say.
              It's not what I say, I'm just pointing folks to the real data.

              Point is, it's all from one place - a source SK seems to think is questionable, maybe because it may be biased, cherry picked, reinterpreted or just plain B.S. It can also be 100 % true and correct. Without peer review/vetting/verification there's no way to tell.

              Because something is written/printed says nothing of its accuracy or veracity.
              It's not all from one place: it's a bunch of individual owners, all of whom are geeky enough to no doubt be very interested in whether their pack is likely to perform to specification over time, submitting the data. There is a whole forum of people discussing the data. There are numerous other indicators of veracity, and there is little incentive for someone to fabricate or mislead (because Tesla owners want to know, right now, if their particular pack is not performing).

              But, aside from that example, there is also a growing body of other published scientific literature illustrating cell longevity over time. And, just because it has been written and published, also says nothing of its accuracy or veracity. However, the papers do show that lifespan can be substantially greater than 500 cycles in the right environment.

              And, on EV forums, there are folks with conservatively-managed packs now clocking seven or eight years of good performance.

              And, on boat forums, there are also folks with packs closing in on a decade of service.

              At some point, each reader has to make his or her own decision on all of these sources, of course. But to say there are "no documented cases" with performance well beyond what Sunking suggested is silly.

              Comment


              • #52
                Originally posted by Sunking View Post
                Nice try Jeff, but all conjecture and not one documented case. Is a Green Mafia Blog site the best you can do?
                Here's another one that shows a similar result:

                https://steinbuch.wordpress.com/2015...radation-data/


                Attached Files

                Comment


                • #53
                  Originally posted by nebster
                  However, the papers do show that lifespan can be substantially greater than 500 cycles in the right environment.
                  I am saying 500 cycles means little, until the energy transferred per cycle is defined. That could be in KWH, or
                  miles traveled, or % depth of charge. Bruce Roe

                  Comment


                  • #54
                    Originally posted by J.P.M. View Post
                    Point is, it's all from one place - a source SK seems to think is questionable, maybe because it may be biased, cherry picked, reinterpreted or just plain B.S.
                    I posted a source that confirms that. It comes from the webpage of Marteen Steinbuch, a professor at the Eindhoven University of Technology. Naturally the forum won't allow me to post the link to it, or the data - but you can Google if you like. He got his data from a survey of Dutch/Belgian Tesla owners, a second survey of owners from the Netherlands and a third survey of owners from the US.

                    No skin off my nose if people believe or disbelieve it. I am always happy to get more data on something like this.

                    Comment


                    • #55
                      Originally posted by nebster View Post

                      This is incorrect.

                      The Panasonic 18650s are rated to ~70% of their original capacity after 500 full cycles: 100% to 0% SOC and back. Of course, lifespan increases dramatically if one elects a narrower charge regime. And lifespan increases if temperature is kept lower. And lifespan increases if cells are held at less than 100% SOC during periods of non-use. (And, by the way, 70% of nominal capacity is far from used up!)

                      None of that is to say that cobalt chemistries are super safe or that everyone should just go wire some crashed packs into their house. But, setting thermodynamic risks aside for a moment, it is clear that NCA and NMC chemistries can be cost competitive in a wide range of use cases.
                      That's the way I read the graphs on that datasheet too. Also, the rate of loss of capacity was diminishing with the number of cycles.

                      Comment


                      • #56
                        Originally posted by jflorey2 View Post
                        I posted a source that confirms that. It comes from the webpage of Marteen Steinbuch, a professor at the Eindhoven University of Technology. Naturally the forum won't allow me to post the link to it, or the data - but you can Google if you like. He got his data from a survey of Dutch/Belgian Tesla owners, a second survey of owners from the Netherlands and a third survey of owners from the US.

                        No skin off my nose if people believe or disbelieve it. I am always happy to get more data on something like this.
                        Understood.

                        Comment


                        • #57
                          Originally posted by bcroe View Post

                          I am saying 500 cycles means little, until the energy transferred per cycle is defined. That could be in KWH, or
                          miles traveled, or % depth of charge. Bruce Roe
                          It's a good point: the thing we care about perhaps most of all is total energy flux. If we only get 1000 cycles when running from 75% to 25%, that would be unfortunate.

                          However, the data suggest that the total energy flux increases substantially as we back away from the knees, as we use lower rates (and therefore less heating), and so on.

                          Put another way, if we went solely by the datasheet values, and our Tesla got 250 Wh/mile while running the battery from 100 to 0 and back again, we should be able to drive 500 cycles * 75000 Wh / 250 Wh/mile = 150,000 miles and then see the battery at 70% SOH. But, from the data submitted, it looks like the packs are achieving more like 92% SOH at that point. Moreover, the degradation curve is flattening. Unless there is another phenomenon that starts to drive cell decay that we can't see yet, the numbers suggest a much longer lifetime.

                          This is one of those rare moments where the manufacturer datasheet values seem to be very conservative. Or maybe it is one of those all-too-common moments where the datasheet tells us information that is not especially relevant.

                          Comment


                          • #58
                            I am try to replace agm batteries with kilovault lithium 4 -12 volt but inverter would not work(off grid manga sine 4400/midnite solar charge controls/21 panels)
                            alte store says these batteries are drop in.

                            Comment


                            • #59
                              Can anyone help? Anyone using Kilovault batter?

                              Comment


                              • #60
                                Not only has it been done successfully, there are several YouTube videos on it.
                                Now if you have the money, Tesla currently has modified the battery array for home use and it

                                Comment

                                Working...
                                X