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

Regenerative Braking Behavior Poll

Discussion in 'Model S' started by Quick2Judge, Mar 29, 2018.

?

Would You Like Regenerative Braking Bring the Vehicle to a Complete Stop?

  1. Yes

    80.3%
  2. No

    19.7%
  1. jgs

    jgs Active Member

    Joined:
    Oct 28, 2014
    Messages:
    1,581
    Location:
    Ann Arbor, Michigan
    Ah, sorry. "ISTR" is "I seem to recall". The 60% number is, as you now see, just my recollection. If I can put my finger on a reference later, I will. Similarly, where did the 85% number come from? Seems very optimistic.

    Oh, and what is this "Tesla Chip"? Googling it just gives a lot of articles about Tesla's in-house ASIC development.
     
  2. aerodyne

    aerodyne Active Member

    Joined:
    Nov 19, 2018
    Messages:
    1,477
    Location:
    Los Angeles
    Both came some where on this forum, but the 85% number I think is also mentioned on various forums and seems reasonable for motor gen efficiency.

    Try Tesla Chip range extender. It is an Aftermarket product.
     
    • Informative x 1
  3. Shadnic

    Shadnic Member

    Joined:
    Feb 8, 2019
    Messages:
    160
    Location:
    San Diego
    I had never heard of Tesla Chip until this thread, which is surprising considering how much gets discussed on this forum. Reading about it now and it's really interesting. Is this something people commonly use?
     
  4. jgs

    jgs Active Member

    Joined:
    Oct 28, 2014
    Messages:
    1,581
    Location:
    Ann Arbor, Michigan
    A Tesla blog on the Roadster (v1) regenerative braking cites "a net efficiency of at most 80% * 80% = 64%". That assumes battery-to-wheels efficiency of 80%, and vice-versa, and is probably the source of the "60% or so" number, I would guess. Possibly the Model S drivetrain is a little more efficient than the Roadster, but there's no way it achieves the 92%+ efficiency you'd need to get a RT efficiency of 85%. The 60% or less number feels about right, too, based on four+ years of driving one.

    Remember we're talking about the whole drivetrain starting from the battery, not just motor efficiency. The Model S induction motor is said to be 93% efficient. LiIon batteries are said to have 80-90% charge and discharge efficiency. So best case -- assuming no other drivetrain losses, not realistic -- is 93% * 90% = 84%. So once you factor in that there are inevitably some other drivetrain losses, you end up with Model S looking not very different from the Roadster's 80%, and that overall 64% RT number.
     
    • Informative x 1
  5. aerodyne

    aerodyne Active Member

    Joined:
    Nov 19, 2018
    Messages:
    1,477
    Location:
    Los Angeles
    I only recently ran across it. No idea if it is recommended or not.
     
    • Like x 1
  6. jgs

    jgs Active Member

    Joined:
    Oct 28, 2014
    Messages:
    1,581
    Location:
    Ann Arbor, Michigan
    For anyone curious about the so-called "Tesla Chip", here's a link to the site. Looks like it's an accelerator curve remapper, you interpose it between the accelerator pedal and the car, so it has an opportunity to lie to the car about how hard you're pressing the accelerator. There aren't any actual test results to back up the claims of greater efficiency and battery life, and without that I find them more than a little dubious, though of course I don't have evidence contra either. I for one wouldn't install one of these in my car if you gave it to me free, but I'd be interested in hearing from anyone who has!
     
  7. aerodyne

    aerodyne Active Member

    Joined:
    Nov 19, 2018
    Messages:
    1,477
    Location:
    Los Angeles
    I think I will pass on the chip, here is why....

    Whether you coast more, by setting regen low, modulating the go pedal more, use the chip, or actually shift into neutral, you have to balance that with the increased probability of using the Bad (Brake) pedal, in which case ALL that excess kinetic energy is wasted.

    In stop and go traffic, I find that TACC regens a lot more than I would, but it rarely brakes. With regen low, or coasting, I think brake useage would increse. By turning TACC off, and intensive modulation of the go pedal, I feel I am more efficient, but also more annoying to those following me.

    So, on a deserted highway with lots of hills, I can see a possible range improvement, like the chip dyno vid implies, otherwise, not so much.
     
    • Like x 1
  8. jgs

    jgs Active Member

    Joined:
    Oct 28, 2014
    Messages:
    1,581
    Location:
    Ann Arbor, Michigan
    I agree. I did plenty of trying to hypermile (just for fun) with my old manual-transmission car. Coasting to a stop isn't really a thing, unless you're coasting uphill.
     

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