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Size and weight of the 40 KW, 60 KW and 85 KW battery (which are available now)?

Discussion in 'Model S: Battery & Charging' started by Benz, Nov 15, 2012.

  1. Benz

    Benz Active Member

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    Size and weight of the 40 KW, 60 KW and 85 KW battery (which are available now)?
    Does anyone know something about this?
     
  2. Oyvind.H

    Oyvind.H Member

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    Don`t think anybody knows what the batteries weigh, but the NCR 18650A cells weigh abut 46 grams each. With approximately 7000 cells that`s 322kg in battery cells alone. Then add connections, cooling etc. and you might be looking at about 450kg.
    Really not that much concidering the weight of a gasoline engine, (full) gas tank, generator and other stuff you need in an ICE car.
     
  3. Benz

    Benz Active Member

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    I was thinking about the possibility of extending the range of the Tesla Model S.
    Would it technically be possible to add 1 extra battery in the compartment where you can normally put your luggage?
    The weight of the car would increase (by 450 kg), that is right, but you would also would have more battery capacity at your disposal.
    Can this idea be transformed into reality?
    Would anyone please have a brainstorm session on this idea?
    Thanks
     
  4. Oyvind.H

    Oyvind.H Member

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    #4 Oyvind.H, Nov 15, 2012
    Last edited: Nov 15, 2012
    Something like that exists for the Leaf:
    Add 40 miles driving range to Nissan Leaf with Enginers add-on battery pack

    But I think it`s more wise to nag Tesla about superchargers, or wait for new Panasonic cells with bigger capacity. Would you pay $20-30,000 for an extra 50kWh in your trunk?

    I read somewhere that the 85kWh currently uses 3100mah batteries (18650A), and that identical 3400mah batteries (18650B) are allready developed so you could theoretically ad 10% to the capacity by paying just a little more for the car. But I do not have a clue if B-cells have the same chemistry, if the prices are sensible or if the 85kWh version already uses B-cells.

    http://endless-sphere.com/forums/viewtopic.php?f=14&t=42646

    Panasonic apparently make the best 18650 cells at the moment:
    The Best 18650 Battery Of 2012 | MetaEfficient
     
  5. VolkerP

    VolkerP EU Model S P-37

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    In contrast to the Enginer extension pack for the LEAF, a Model S battery extension pack should be hooked up not only to High voltage circuits, but to the battery coolant loop, and the battery management system, too. This will considerably complicate things.

    Tesla engineers indicated that there's space left inside the battery pack for additional cells. I think they just chose to draw a line in sight of cost and weight matters. In the future, you might get a special edition pack crammed to the hilt, or even one with higher capacity cells as Oyvind indicated.

    But I would not put my money on that. Roadster owners longing for an upgraded pack still sit on the dry beach - I guess even though Tesla was offered enough $$ for that :wink:
     
  6. Johan

    Johan Took a TSLA bear test. Came back negative.

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    It's probably not as simple though as just switching one cell for another. The new 3400 mAh 18650 cells have different properties than the currently used 3100 mAh ones: they operatee at slightly different Voltages, have different charge/discharge characteristics, different characteristics when it comes to how they generate heat when charging/discharging etc. etc.

    For the 85kWh battery pack, for example, there have been many many considerations as to why it has been constructed the way it is constructed: why did they choose to put x number of celles in parallell and y number of cells serially to come up with the current total Voltage and Amperage (they could have coupled the cells in a number of different combinations/setups)? Well, it was probably the optimum way to put the pack together when all factors were considered; temperature management, charging/discharging management and battery balancing, maintenance - the ability to change one "sheet" (consisting of many cells) if it goes bad, proper Voltages for the motor to operate optimally etc. For example if they went with more cells in parallell and less in serial coupling, the total energy would be the same but with lover Voltage and higher total Amperage. Lower voltage can be a pro sometimes (less insulation needed - contacts can be physically closer to each other since there is less risk of "arching" of current) but also a con (too low voltage for the motor for example). Increased amperage makes it so that you need larger diameter wiring and contacts for example.

    This is all very complex and there are many, many considerations to be made. So I think that to make a new battery pack with new cells, even if they are just the next generation of the same type of cell, you need to go back to the drawing board and in one way start over.
     
  7. Oyvind.H

    Oyvind.H Member

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    Well, they made about 2,500 roadsters? That`s like a months production of Model S, which means the market for addons would be huge for the Model S compared to the Roadster.

    Anyway, I agree that Tesla has thought long and well about what options to offer, so there`s probably a good reason why there doesnt exist a 100kWh version even though that would be the one I`d buy.

    In Norway, a car with 500km range would reach all major cities where most people live, so no charging would be needed if the car was able to acchieve 500km (300miles) on one charge whatever weather/load.

    - - - Updated - - -

    I really hope the car is more versatile than that, or at least that we`re talking about simple software changes? As long as charge and discharge stays within current limits, and the new cells are able to provide about the same voltage as the old ones. What I`ve understood is that the current cells are kept well within Panasonics limits to charge/discharge etc.

    Addin an extra sheet or two, or changing the current cells for new ones, should result in minor software changes.

    Maybe the simplest extension pack is a DC-DC charge pack?
     

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