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 or making a Paypal contribution here: paypal.me/SupportTMC

P85D - Maximum regen power

Discussion in 'Model S' started by WarpedOne, Jan 22, 2015.

  1. WarpedOne

    WarpedOne Supreme Premier

    Joined:
    Aug 17, 2006
    Messages:
    2,651
    Location:
    Slovenia, Europe
    Did anyone looked at display while doing full power regen?
    Is it still exactly 60kW or does it go lower (i.e. higher power)?
    Pics, videos would be great :)
     
  2. NOLA_Mike

    NOLA_Mike Active Member

    Joined:
    May 11, 2013
    Messages:
    1,556
    Location:
    Hammond, LA
    My P85D will go beyond 60 kW on regen (hard to tell exactly where but I'm gonna guess I've seen it up to 70 kW on the regen scale).

    No pictures, no video, sorry.
     
  3. ra-san

    ra-san Member

    Joined:
    Dec 26, 2008
    Messages:
    292
    Location:
    San Diego, CA
    Will watch, but can say that I've never noted it going much, if any, above 60. Feel wise, I still feel like there could be a lot higher max Regen than what it does now before it would start to feel like too much.
     
  4. billarnett

    billarnett Member

    Joined:
    Nov 15, 2008
    Messages:
    293
    Location:
    Emerald Hills CA
    Please, please, please Tesla, give us an option for much stronger regen on the dual motor cars!
     
  5. Panu

    Panu Member

    Joined:
    Jan 9, 2015
    Messages:
    280
    Location:
    Uusimaa, Finland
    I think they want to save the battery. Fast charging can easily cause battery degradation. Early Model S owners also say they were told not to use SuperCharger often because of this.
     
  6. Todd Burch

    Todd Burch Electron Pilot

    Joined:
    Nov 3, 2009
    Messages:
    4,733
    Location:
    Smithfield, VA
    Tesla has never said that frequent Supercharging accelerates battery degredation. Officially, Tesla has always maintained that you can Supercharge as much as you want, as often as you want without any undue harm to the battery. However, they have of course always maintained that frequently charging to high SOC will cause accelerated degredation.

    In fact, when the Supercharger was introduced back in--I think--October of 2012, Elon or JB was asked this very thing, and the response was to Supercharge as often as you'd like without undue battery pack harm.
     
  7. Panu

    Panu Member

    Joined:
    Jan 9, 2015
    Messages:
    280
    Location:
    Uusimaa, Finland
    I don't think they can say it officially. If you read about Li-Ion batteries the message is always that the faster you charge the more the battery will degrade. Tesla and Panasonic have probably solved much/part of the problem but it's hard to believe they would have solved it fully. It would be nice to see some test results either from Tesla or from some independent party.
     
  8. NOLA_Mike

    NOLA_Mike Active Member

    Joined:
    May 11, 2013
    Messages:
    1,556
    Location:
    Hammond, LA
    With my admittedly fairly limited observation of this it seems the best chance of seeing it above 60 is when coming off an interstate let up off the accelerator completely on the off ramp. Coming down from high speed with full regen and mine goes over (under?) 60 kW.
     
  9. WarpedOne

    WarpedOne Supreme Premier

    Joined:
    Aug 17, 2006
    Messages:
    2,651
    Location:
    Slovenia, Europe
    What degrades the battery is heat. Almost no LiIon batteries out there get active cooling while charging. So they heat up, faster the charging, more heat buildup and more degradation. But when you actively remove heat there is much much less degradation. In the end it can be so that faster charging degrades LESS than slower charging because battery is exposed to a bit higher temps for shorter time.

    - - - Updated - - -

    Yes, I expect regen to max out only at and maybe even only above legal HW speeds.

    90kW at 20mph would brake your nose.
     
  10. apacheguy

    apacheguy Sig 255, VIN 320

    Joined:
    Oct 21, 2012
    Messages:
    3,709
    Location:
    So Cal
    This is my recollection as well. Never remember Tesla saying not to supercharge often. If the pack can handle 90 kW at a SpC it can definitely handle > 60 kW of regen.
     
  11. billarnett

    billarnett Member

    Joined:
    Nov 15, 2008
    Messages:
    293
    Location:
    Emerald Hills CA
    And some of the Superchargers are 120kW.

    If the battery can put out 515kW when your right foot's to the floor it should be able to take in 515kW when you left foot is to the floor, too. Especially since doing so will obviously last for only a couple of seconds whereas the right foot may be floored for much longer :)
     
  12. LetsGoFast

    LetsGoFast Active Member

    Joined:
    Oct 13, 2014
    Messages:
    1,342
    Location:
    Virginia
    #12 LetsGoFast, Jan 24, 2015
    Last edited by a moderator: Mar 13, 2016
    It does go slightly past 60. I've seen it a number of times. I shot a brief video of full regen from 85mph or so to demonstrate

     
  13. WarpedOne

    WarpedOne Supreme Premier

    Joined:
    Aug 17, 2006
    Messages:
    2,651
    Location:
    Slovenia, Europe
    So, regen stops just a bit under halfway between 60 and that "unmarked 120kW" mark.
    Exact middle would be 85kW, so it looks like it goes up to ~80kW.

    Trivia:
    halfway between 0 and 15kW mark is: ~10 kW
    halfway between 15 and 30W mark is: ~21 kW
    halfway between 30 and 60kW mark is: ~42 kW
    halfway between 60 and 120kW mark is: ~85 kW
     
  14. Panu

    Panu Member

    Joined:
    Jan 9, 2015
    Messages:
    280
    Location:
    Uusimaa, Finland
    The distance between 60 and the last mark is less than the distance between other marks so I think it's more like 100kw mark. But it seems to go full half way at the beginning.
     
  15. ratsbew

    ratsbew Member

    Joined:
    Mar 3, 2012
    Messages:
    371
    How is the power put in the battery? I'm assuming (guessing) that the motor creates alternating current during regen....how is that AC turned into DC for the battery? There is no regen difference between single and dual chargers so the chargers can't be doing it. Or am I wrong and the motor generates DC?
     
  16. Danal

    Danal electricmotorglider.com

    Joined:
    Dec 11, 2014
    Messages:
    431
    Location:
    Fairview, TX, United States
    I've seen your simple question cause flame wars in technical forums. Is a brushless motor that is being "commutated" by a processor based controller/rectifier AC or DC? At any given instant, the coils that are energized inside the motor see current in one given direction. DC. Over time, as the motor rotates, any given coil sees current in each of the two possible directions. AC. But not "sinusoidal" AC like you find in a wall. It is more square wave (really sort of a trapezoid) and is also PWM (Pulse Width Modulated) to provide throttling via voltage averaging by using the self-same motor as a giant inductor.

    Whew..!

    So, ignoring the nomenclature debate, think of it this way: When current is flowing from the DC traction battery pack to the Motor, the circuitry in the controller/rectifier applies that DC in the correct directions (alternating) to the correct coils (different ones at different times) to create a rotating magnetic field inside the motor that, in turn (pun intended), creates torque.

    During regen, the opposite occurs. That is, the inertia of the car is transformed by the tires/wheels/gears leading back to the motor into a mechanical torque input to the motor; which means the motor is really a generator at this moment. As the innards of the motor turn via this input mechanical force, the controller/rectifier applies the correct coils output current (different ones at different times), which is alternating, always applying that current to the traction pack in the correct directions at the correct times to put current back into the traction pack in only one direction (DC), thus charging the pack.




    Rephrased more simply: Circuitry takes DC from the pack and switches it around to make the motor rotate, that same circuitry can take the current that is switching around as it comes from a rotating motor (generator) during regen and apply it to the DC pack.

    Make sense?
     
  17. ratsbew

    ratsbew Member

    Joined:
    Mar 3, 2012
    Messages:
    371
    Makes perfect sense! Thanks! So the control electronics are basically "faking" an AC power source. Fascinating.
     

Share This Page