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Does performance suffer with lower charge level?

Discussion in 'Model S: Driving Dynamics' started by Evbwcaer, Jul 30, 2014.

  1. Evbwcaer

    Evbwcaer Member

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    I see a wide range of 0-60 times quoted for P85's on youtube videos and reviews, I think 3.9-4.8.

    Does the state of charge effect the performance or driving characteristics of the car?


    Thanks
     
  2. Gizmotoy

    Gizmotoy Active Member

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    Yes, SOC has an effect. Those that report going to the drag strip usually have their fastest times in their earliest runs. As the battery drains, performance is impacted. I'm not sure anyone's tried to do a study to quantify the effects, though.
     
  3. David99

    David99 Active Member

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    Technically it would. The battery voltage is lower at a lower state of charge which means there would be less power available. Not sure if Tesla compensates for the voltage change and allow a higher current (Ampere). So many other factors affect acceleration. I don't think it would be easy to isolate how much of all the factors the voltage would be.
     
  4. flashflood

    flashflood Member

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    Undoubtedly this is part of the regulation, but there are limits. As voltage drops, you can draw more current, but then (a) you have higher i^2*R heating, and (b) battery voltage sags under load, so you have to draw even more current, which induces even more voltage sag, etc.

    That said, a Li-Ion cell is fully charged at 4.2V and almost completely depleted at 3.5V, so the operating voltage range is not huge. But the SOC effect is definitely noticeable. Mr. T is always a little zippier with 200+ miles in the tank, and a little less so below 50 miles.
     
  5. stopcrazypp

    stopcrazypp Well-Known Member

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    It has not be quantified, but if it's like most batteries (and the batteries are the actual performance bottleneck and not something else), at around 50% SOC is where the advertised performance is rated at. You only get worse when it's significantly lower than that, and you get better when the battery is near full.
     
  6. strider

    strider Active Member

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    Yes. You'll notice when you get to a low state of charge that the car limits power by placing a yellow bar on the power meter. At lower states of charge, the cells generate more heat for the same power output so Tesla does that to limit damage to the cells.

    Also, for the drag strip runners, the other factor is the PEM and motor heating up and Tesla will limit power due to those reasons as well. High charge and cold will yield the best acceleration.

    Finally, one big thing to look at when comparing 0-60 times is whether they are using a 1-foot rollout. For your reading pleasure:
    How We Test Cars and Trucks
    The Importance of 'Rollout' - Feature - Car and Driver
     
  7. William13

    William13 Member

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    With my P85 I notice a large difference with my 0-60 times. Much faster with a full battery. At least one second slower with less than 100 miles in the tank.
     
  8. invisik

    invisik Member

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    I do think it's feels torque-ier at full charge.....

    -m
     

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