Tesla Model S Battery Degradation

Discussion in 'General' started by Carcus, Apr 4, 2017.

  1. Carcus

    Carcus Well-Known Member

    DENDRITES ?

    Fire-starting battery dendrites go with the flow
    https://www.chemistryworld.com/news/fire-starting-battery-dendrites-go-with-the-flow/3008867.article
    "When a lithium–ion battery charges, lithium ions travel from the cathode to the anode; the ions flow the other way during discharge. At a lithium metal anode, lithium ions leave and return to the surface unevenly. This means that after several charging cycles, spiny projections called dendrites begin to grow from the electrode’s surface. As these lithium dendrites grow, they can pierce the membrane separator in the middle of the battery, touch the cathode and short circuit the cell. This can starts fires."

    Three Ways That Lithium Dendrites Grow
    https://www.designnews.com/electronics-test/three-ways-lithium-dendrites-grow/78500767259733
    "In the study, when the separator was pierced, the battery was in danger of catastrophic failure, although its perilous condition was not necessarily apparent. Bai said, “Our unique transparent cell revealed that the voltage of battery could look quite normal, even though the separator has been penetrated by a lithium metal filament. Without seeing what is happening inside, you could be easily fooled by the seemingly reasonable voltage, but, really, your battery has already failed.”

    Which dendritic growth mechanism occurs depends not only on the level of current, but also the age and charge history of the lithium battery. The thresholds for the dendritic growth types become lower as the battery ages. In addition, there is a push to faster charging, particularly for EVs, and the higher currents required can result in differing types of dendrite formation. If solid state lithium batteries are to become viable, the results of the study will need to be considered to control the differing types of dendrites that are formed. “Battery operation is highly dynamic, in a very wide range of currents. Yet its disposition varies dramatically along the cycle life. That is why this becomes necessary,” Bai said."
     
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  2. Carcus

    Carcus Well-Known Member

    Whatever the problem(s) is(are) ... the software "updating" (i.e. usable capacity drop) is likely going on with every car they've manufactured , .. not just a small group of "A type batteries" in S85's ... or whatever(imo)

    youtube:
    Model 3 lost 6 % battery after software update
    /3 to 5 kwh capacity taken away with software update, range constant changed to mask the drop in range
     
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  3. Carcus

    Carcus Well-Known Member

    **update**

    Tesla has proposed mediation. Could be Jan or Feb before the outcome on this (if it goes this way) is known.

    /my guess -- Tesla would cough up a big chunk of change to keep this out of the limelight right now -- too much at stake as sales now ramping up (especially the China potential)
     
    Last edited: Oct 30, 2019
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  4. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Carcus:

    At some point, the derating costs big range losses and then people will get pissed off. Until that time, have you watched one of their presentations? The Y reveal sounded like a Trump Rally without the Lock them, Beat them, Kick them out chants.

    Wayne
     
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  5. Carcus

    Carcus Well-Known Member

    Some more indication that the software "updating" (pulling back range in order to prolong battery longevity) is going on with the model 3 as well. Some model 3 owners are reporting a 7% to 10% loss in range in the first year -- complicated by winter but it will probably be more clear when this summer rolls around ( -- maybe)

    https://teslamotorsclub.com/tmc/threads/range-on-midrange-reduced-to-219-miles.164621/page-9

    Any Tesla battery concerns certainly do not seem to be affecting the stock price -- and just by what I see on the street -- sales either.
     
  6. xcel

    xcel PZEV, there's nothing like it :) Staff Member

  7. Carcus

    Carcus Well-Known Member

    Latest random thoughts ...

    I'm starting to wonder/suspect if supercharging has been the biggest culprit in the demise of some (a few, many?) Tesla batteries. Perhaps the heavy charging (i.e. owners who supercharge several times per week*) has been causing 'dendrites' to form in the batteries. Dendrites (I think) pose a risk for sudden failure for individual cells (and perhaps, rare but possible -- catastrophic failure of the whole pack). Dendrites (I think) do not necessarily show up in the form of large capacity reduction.

    I also wonder if the dendrites are showing up as increased internal resistance*** ... especially at higher voltages (i.e. near the 4.2v max capacity of the cells) .. and that all the excessive running of compressors/fans was actually Tesla testing for differences in internal resistance (***add -- sudden voltage loss(?)) (if they have that capability) at different levels of cell voltage, thus Tesla trying to identify the risky batteries and provide the appropriate software update "nerf" to the individual cars with a high "suspected dendrite count".

    /really just random thoughts from reading through the Tesla forums/youtubers about owners observations, and scanning through a few battery technical papers --- I don't remember anyone putting this out there exactly -- but the pieces would fit together
    //add ,... may show up as sudden voltage loss in the cell with a penetrated membrane

    * as opposed to the Tesloop cars that were supercharged several times a day -- and were able to "beat the clock" as Dahn says
     
    Last edited: Feb 4, 2020
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  8. Carcus

    Carcus Well-Known Member

    This paper (way above my electrical/chemistry ability to understand) did get me wondering if maybe the condition X, condition Y that the knowledgable dude on the Teslamotorsclub forum might have been talking about was actually mossy and serpentine dendrites.---


    Transition of lithium growth mechanisms in liquid electrolytes
    https://pubs.rsc.org/en/content/articlehtml/2016/ee/c6ee01674j

    something more recent: ...

    "In the study, when the separator was pierced, the battery was in danger of catastrophic failure, although its perilous condition was not necessarily apparent. Bai said, “Our unique transparent cell revealed that the voltage of battery could look quite normal, even though the separator has been penetrated by a lithium metal filament. Without seeing what is happening inside, you could be easily fooled by the seemingly reasonable voltage, but, really, your battery has already failed.”

    Which dendritic growth mechanism occurs depends not only on the level of current, but also the age and charge history of the lithium battery. The thresholds for the dendritic growth types become lower as the battery ages. In addition, there is a push to faster charging, particularly for EVs, and the higher currents required can result in differing types of dendrite formation. If solid state lithium batteries are to become viable, the results of the study will need to be considered to control the differing types of dendrites that are formed. “Battery operation is highly dynamic, in a very wide range of currents. Yet its disposition varies dramatically along the cycle life. That is why this becomes necessary,” Bai said."
    Three Ways That Lithium Dendrites Grow
    New research shows that lithium metal crystals grow in three different ways in lithium batteries, depending upon the current level at which charging takes place.
    https://www.designnews.com/electronics-test/three-ways-lithium-dendrites-grow/78500767259733

    Interactions between Lithium Growths and Nanoporous Ceramic Separators
    Peng Bai
    https://www.cell.com/joule/fulltext/S2542-4351(18)30403-3
     
    Last edited: Feb 4, 2020
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  9. Carcus

    Carcus Well-Known Member

    From the comments section on Nylands youtube:

    This is NOT only a Tesla thing. Porsche is also limiting the charging speed for the Taycan after a not specified amount of DC-charging. It ist written on the German Porsche Website under "Laden": https://www.porsche.com/germany/accessoriesandservices/porscheservice/vehicleinformation/bev/ In English: "The predominant use of CCS quick charging stations leads to an increase in charging times in the long term. A charging capacity of maximum 50 kW is recommended for regular DC fast charging. AC charging (AC = alternating current) is recommended for charging in the home. By using an industrial socket (AC) you achieve a higher efficiency and a significantly shorter charging time compared to charging at a household socket."

    So we've seen this "supercharge pullback" in some form or other from:

    Tesla
    Porsche
    Audi
    Nissan
    Hyundai
    .... and I'm sure others/others to follow.
     
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  10. Carcus

    Carcus Well-Known Member

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  11. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Carcus:

    There are still plenty of DCFC charging owners reporting that they have experienced little to no degradation. For others, wow. :(

    Wayne
     
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  12. Carcus

    Carcus Well-Known Member

    Yep. Huge differences in what people are reporting. I think most of us (myself included) really haven't come to terms with how sensitive these batteries are to different use/environment scenarios.

    Q. Will my battery last 300 cycles ... 600 cycles.... 1,000 cycles ... more?????
    A. Well that all depends --- here's 178 pages of 'depends' to contemplate ...

    Aging of Lithium-Ion Batteries in Electric Vehicles
    https://mediatum.ub.tum.de/doc/1355829/file.pdf

    add -- and I'm still leaning towards Tesla's Super Charging as being the biggest detriment
     
    Last edited: Feb 10, 2020
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  13. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    I found a study that ran long-term tests on cell phone batteries. The put them on a machine and repeatedly charged and discharged them and checked degradation.

    Draining to 50% and slow charging to 75% caused half the degradation of draining to 30% and fast charging to 100%.

    They did find that fast-charging to 80% and then slow charging the last 20 was less damaging than full fast charge. I believe that's the game Tesla is playing so it's not all bad news.
     
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  14. Carcus

    Carcus Well-Known Member

    No. It's not all bad news. It's just not as good as Elon and all the Tesla fanboys and girls would have you believe.

    The reports of the death of internal combustion engines have been greatly exaggerated. And why it is important to keep working on the advancement of ICE ? ...

    An impressive 1 million + views and nearly 10,000 (!) comments in 5 days ...... (even though he left out my favorite battery topic --"Degradation --- I GOTS TO KNOW!")

    youtube: Why Gas Engines Are Far From Dead - Biggest EV Problems
     
    Last edited: Feb 10, 2020
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  15. Carcus

    Carcus Well-Known Member

    Apparently, Tesla has come to the point where they will now disable your car until you do the required updates ... "

     
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