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Power draw to achieve 691 HP

Discussion in 'Model S: Battery & Charging' started by scaesare, Oct 10, 2014.

  1. scaesare

    scaesare Active Member

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    #1 scaesare, Oct 10, 2014
    Last edited: Oct 10, 2014
    So... 691 HP is close to 50% more HP than the P85's rating of 470.

    The P85 has been observed to draw ~360kW at max acceleration. That equates to pulling about 900A with a pack voltage of ~400v (round numbers).

    That implies the P85D will be drawing nearly 540kW / 1,350A...

    Wow.
     
  2. David99

    David99 Active Member

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    The voltage drops quite a bit when you draw that much power, so the resulting Ampere would be much higher.
     
  3. glhs272

    glhs272 Unnamed plug faced villian

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    I thought the P85 was already pack limited at 360kW. Elon stated the P85D is using the same pack, so I wonder how they are squeezing the extra amps out of the original battery.
     
  4. scaesare

    scaesare Active Member

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    Incidentally... that would be slightly greater than a 6C​ discharge rate...
     
  5. ElSupreme

    ElSupreme Model S 03182

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    This is probably done with slight of tongue.

    The combined power of both motors is 600+ horsepower. But there isn't any time when they are both putting out maximum power. I would guess that maximum power output is unchanged or slightly higher. At low speeds the power outputs of the motors isn't as much. So adding a second motor allows increased power probably to about 60 mph. After that you hit the battery power limit, and preform much like the old P version.

    There is almost certainly another inverter added to the mix, so if the inverter was the power/current limiting device the new D might be able to pull more power even at peak output.
     
  6. widodh

    widodh Model S R231 EU

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    Fyi, it's 360kW and 540kW.

    kWh is energy and kW is power. That mistake is made a lot here and on other websites.

    It's a 85kWh battery and the power draw will be 540kW :)
     
  7. scaesare

    scaesare Active Member

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    Absolutely right... between being distracted and being used to using the units for battery size I typo'd it. Thanks.
     
  8. Sad

    Sad Member

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    I hope not, because if that's the case, then Tesla better correct that wrong perception ASAP, as it would be dishonest (and would create negative press). Hybrids are a bit in the same situation, and manufacturers never add up the peak power of both engines (unless the two engines can effectively deliver their peak output at the same time).
     
  9. jaanton

    jaanton Roadster NA #1026

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    This topic seems like a non-sequitur. hp and kW are both measurements of power and have a direct mathematical relationship. Google search "691 hp to kW".
    At the X reveal I mentioned to some Tesla employee that it seemed to me that the two motors would need to draw about 1/2 a MW to hit the times they were talking about.
    I think they always were targeting the battery producing around 540 kW at least on a surge level. And when you think about it, the pack has to absorb power to supercharge on a continuous level also. This math also suggests why the Roadster will not supercharge. The sport model has 288 hp which is about 215 kW. If that's a surge level the continuous must be much less.
     
  10. wk057

    wk057 Senior Tinkerer

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    The main pack fuse is a quick response 630A fuse on the 85kWh pack.

    There is also a precharge resistor, which means there must be some large capacitors in the inverter/drive unit(s) (since there are no large power capacitors in the pack itself). My assumption is that the car will dump the power from the capacitors during the full acceleration times and quickly recharge them.

    This way the pack itself never (rarely?) sees large current draws beyond the fuse rating.

    This is a bit of speculation, but makes sense based on the components in the pack.
     
  11. p85dk

    p85dk Member

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    Just bumping this tread

    How big a power draw are we actually seeing from the P85D in real life? I know I'm not seeing anything near 540kW, I'm scary close to the power draw of the P85.

    Is the improved acceleration more down to better traction because of the AWD rather than more power? On a dyno I had my P85D measured pushing out approx. 430 metric hp and of course crazy massive torque.

    And the big question - will we ever experience the true power potential of the P85D?
     
  12. Matias

    Matias Active Member

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    #12 Matias, May 24, 2015
    Last edited: May 24, 2015

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