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90KWH Battery Current / Voltage and degradation vs 85KWH

Discussion in 'Model S: Battery & Charging' started by thegruf, Jul 19, 2015.

  1. thegruf

    thegruf Member

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    Is the new cell type better or worse for

    Current - can it maintain higher discharge currents for longer ie chemically and thermally?

    Voltage - did I read correctly that actually the cell voltage is a bit lower than the existing cells in the 85KWH battery.
    If in fact it is a bit lower could this in theory mean that the P90D would be slower than a fuse modified P85D at higher speeds as the motor back emf builds up?

    and what about degradation -
    Is this new technology claimed to have longer lifetime?
     
  2. thegruf

    thegruf Member

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  3. DrManhattan

    DrManhattan Member

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  4. apacheguy

    apacheguy Sig 255, VIN 320

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    Suppose these are the new cells being used in the 90 kWh pack with silicon oxide anodes.
     
  5. techmaven

    techmaven Active Member

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    Interesting that the gravimetric density is using rated capacity instead of nominal capacity. Most data sheets have only nominal capacity.

    Using the top level nominal capacity, the specific energy is 259 Wh/kg. Most data sheets also use 23-25 degrees C, not 20.
     
  6. NielsChr

    NielsChr Member

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    the cell in the linked sheet (BF) seams to have same capacity as the (B) cell. so doubt this is the cell - it is though a litle lighter and could potential give the pack a higher capacity. that require tesla to build a new pack with more # cells in the pack ( not likely).
    with the same weigth of the pack they could include up to 160 cells more. each with a capacity of 12 watt. total extra capcity would be only 2 kw, so the numbers does not match.

    anyway if this is typical charteristics of the new anode then it seams it hold a larger voltage while under load - wich should help keep the hk up under load.
     
  7. okashira

    okashira Member

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    The 90kWh pack is probably (99%) NCR18650GA.
     
  8. AmpedRealtor

    AmpedRealtor Active Member

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    Tesla is using a small amount of silicon in the negative anode. This allows for a smaller anode, which in turn allows you to increase the amount of energy storing material in the battery. That's why we are seeing a tiny increase. It's purely from the result of adding silicon to one of the anodes. Per a research article that I read, currently only a tiny amount of silicon can be added to the anode without causing the anode to be destroyed quickly over time. Silicon causes the anode to expand and contract to an extent that degrades the anode very quickly versus pure graphite anodes. One of the challenges, according to this article, is mitigating the degradation caused by the addition of silicon.

    Given the above, I probably wouldn't expect any improvement to the degradation curve.
     

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