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Something fishy about the batteries in Powerwall.

Discussion in 'Tesla Energy' started by jdevo2004, Aug 13, 2016.

  1. jdevo2004

    jdevo2004 Member

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    OK, in this video of the Gigafactory tour at 30:00 the tour guide tells us that each Powerwall consists of a "pod". Each pod consists of 2 modules. A Powerpack consists of 16 pods or 32 modules. He states the module of 14x32 cells is the same form factor that is used in the model S. He later states that there are 16 modules in the Model S.

    Some quick calculations:
    1 module has 14x32 = 448 cells
    A Powerwall has 2 modues = 896 cells
    A Model S has 16 modules = 7168 cells
    A Powerpack has 32 modules = 14336 cells.

    This is the fishy part. A Powerwall is rated 6.4Kwh and a Powerpack is rated 100Kwh. That would mean the batteries used in them would have a capacity of only 2.0ah a piece. This is a very low capacity battery. In fact 2.0ah is very old technology. Not even the Roadster uses such small capacity batteries.

    My theory is that since the Powerpack and Powerwall are going to have to endure the same sort of charge/discharge cycles as a Model S, Tesla is actually using the exact same batteries for both their vehicles and their Powerwall products to reduce overall costs of said battery type.

    Now if we go off the very latest news that Tesla is about to introduce a 100D version of the Model S, we can suppose that they already have that battery in stock and are actually using said battery in their current 90D vehicles. This battery would have a 4.0ah rating.
    If that is the case, and they are in fact using the same batteries for all of their operations, then the Powerwall would have an actual rating of 12.8Kwh and the Powerpack would have a nice round rating of 200Kwh.

    I might be right or I might be wrong, but you have to agree that Tesla using a 2.0ah rated battery for anything is pretty unlikely.
     
  2. Yggdrasill

    Yggdrasill Active Member

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    The Tesla Energy products use the NMC chemistry, while the vehicles use NCA. NMC has much better durability (5000+ full cycles vs 500-1000 full cycles), whereas NCA has much better energy density (280 Wh/kg vs something like 150 Wh/kg).
     
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  3. -=buzz=-

    -=buzz=- Member

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    Given the expectations for industrial appliances and home installations regarding reliability and performance it's also reasonable to expect some overprovisioning like only using the 20-80% range of the available cell capacity
     
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  4. ecarfan

    ecarfan Well-Known Member

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    Yes that seems the likely explanation. What is optimal for a vehicle is not optimal for stationary storage. Tesla is, as usual, making the smart choice for what works best in a particular use case.

    Nothing "fishy" at all, just logic.
     
  5. vgrinshpun

    vgrinshpun Active Member

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    Deleted - wrong thread
     
  6. 1208

    1208 Active Member

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    Thanks god. Was worried by the title that the powerwall smelt of fish.
     
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  7. GoTslaGo

    GoTslaGo Learning Member

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  8. trils0n

    trils0n 2013 P85

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    Very difference charge/discharge profile for Model S and stationary. Stationary is designed for daily charge/discharge. Model S is closer to weekly. That is one reason they use different chemistry between the two products. NMC for stationary, NCA for the cars.
     
  9. JPP

    JPP Active Member

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    Also note that the Powerwall is assembled in the Gigafactory from imported 18650 cells. No significant production of the new 21700 yet.
     
  10. EarlyAdopter

    EarlyAdopter Active Member

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    And here with that thread title I thought someone had opened up a Powerwall to find a bunch of electric eels inside.

    Disappointed.
     
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  11. Aussie

    Aussie Member

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    There is nothing old about 2Ah cells. They are just lower energy density but have the advantage of higher safety and cycle life. No need to go for high density in residential energy storage.

    No, the opposite is true. Tesla is not using the same batteries, no even close. The new Powerwall is going to use Samsung 21700s so every Tesla Energy product will feature cells NOT coming from the Giga Factory.

    We don't have to agree. :) 2.0Ah 18650s are very common in Energy storage.
     
  12. jdevo2004

    jdevo2004 Member

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