TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker and becoming a Supporting Member. For more info: Support TMC

The reality of tesla?

Discussion in 'Roadster 2008-2012' started by serious7, Jul 9, 2009.

Tags:
  1. bolosky

    bolosky Member

    Joined:
    May 5, 2009
    Messages:
    685
    I think you're confusing energy and power density. Going from 2.4ah to 4.8ah doesn't (necessarily) mean you get twice the current from the cells, it probably means that you get the same current for twice as long.

    With current technology, you can get high power/low energy cells or vice versa, but not both. My point is that the Roadster needs the number of cells that it has to generate the power to get the acceleration (and presumably to absorb the power from the regen breaking). Unless the power density of the high energy cells, or the energy density of the high power cells gets better, you're stuck with the current cell count or lower performance (or, I suppose lower range if you switch to high power density cells).

    When the Tesla folks were in Seattle last fall, someone asked them about building a Roadster with a half-sized battery pack (and so lower weight & higher acceleration) for track use. They said that it wouldn't work because they need all the cells they have for power, so I'm guessing that there's not all that much wiggle room.
     
  2. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    18,101
    Location:
    Central New York
    It's very possible that ah capacity can increase AND power output can increase. Case in point, the newest prismatic cells from Sky Energy at 180ah are the same size as their older 160ah cells, and the C rate has increased from 3C/10C to 4C/12C. Even if the C rate didn't increase 1C from the newer cell is higher than 1C from the older cell.
    I'm surprised Tesla has stated they need the full pack for performance, does the vehicle's performance significantly decrease with a half depleted pack?
     
  3. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    18,101
    Location:
    Central New York
    My understanding of cell rating is the ah rating is the 1C rate, so 2.4 to 4.8 at the same C rating should mean twice the current in the same amount of time.
     

Share This Page

  • About Us

    Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.
  • Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


    SUPPORT TMC