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Why does regenerative braking not work well in the cold?

Discussion in 'Model 3' started by argon2018, Feb 11, 2019 at 6:20 PM.

  1. argon2018

    argon2018 Member

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  2. MentalNomad

    MentalNomad Member

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    Because when the battery is cold, it can't accept charge very quickly. The regen braking is based on pushing electricity into the battery, and if the battery can't take it, you can't do the braking.

    If your battery is warm because you've recently been charging, or if the battery warms up after you start driving, you'll see the regen creep back up to normal.
     
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  3. EV-lutioin

    EV-lutioin Active Member

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    Cold batteries don't charge as well.
     
  4. VT_EE

    VT_EE Member

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    You can actually damage the battery by trying to force too much current into it when it's cold. Heavy regen produces lots of current, which is why Telsa limits regen at non-optimal temperatures.
     
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  5. ckoval7

    ckoval7 Mild One

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    Lithium Ion batteries have a negative temperature coefficient, which means the colder they are the more resistance they have. When they have a higher resistance they simply cannot pass as much current, which in turn limits your regen.
     
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  6. RayK

    RayK Member

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    First of all it's BRAKE not BREAK.

    Secondly, yes.
     
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  7. Garlan Garner

    Garlan Garner Well-Known Member

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    I like the title of your thread asking if there are any geniuses out there.

    Answer = plenty. ( But only a few know what they are talking about ). lol
     
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  8. Powered By Jay

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    I imagine a higher peak current can be drawn from the battery when driving than the amount of peak current returned during regen. On cold mornings I get the limited regen alert, but no indication of limited driving power.
     
  9. Garlan Garner

    Garlan Garner Well-Known Member

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    I've received both. I've received both the regen alert as well as the limited battery power alert. Of course it was -20F outside.
     
  10. CAAD

    CAAD Member

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    I was a bit surprised that at 57F triggers it, parked in the garage.
     
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  11. ewoodrick

    ewoodrick Active Member

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    Limited regen isn't really impacted by cold, it's the battery that is.
    When you charge to 100%, you are going to get limited regen in the summer. Regen is the charging of the battery from coasting. If the battery is full, it doesn't accept any more charge and therefore the regen has no where to go.
    When the battery is cold, the overall capacity is less and therefore the ability to charge / regen is even worse.
     
  12. SageBrush

    SageBrush 2018: Drain the Sewer

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    This is the part of the story I have trouble understanding but I suppose it means that the energy wants out of its bottle
     
  13. novox77

    novox77 1.21 Gigawatts

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    2nd law of thermodynamics. that battery wants to come into equilibrium (of charge) with its environment all by itself :)

    Given sufficiently cold weather, you will see the throttle-side limited too. It's much harder to trigger. All of this is Tesla keeping the battery as healthy as possible. If other EVs have "better" regen, you first have to question if they even considered battery longevity into their design decisions.
     
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  14. Matias

    Matias Active Member

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    Short answer; to protect the battery.
     
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  15. Garlan Garner

    Garlan Garner Well-Known Member

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    #15 Garlan Garner, Feb 12, 2019 at 9:59 AM
    Last edited: Feb 12, 2019 at 10:10 AM
    Maybe we can do an experiment to find out what the car/battery/regen really feels like.

    When its -20F - Take off all of your clothes ( cars are naked unless they are wrapped in ppf or something ) and stand outside and try to eat something after being out there for …..lets say.....4 hours of just standing. How much regen ( food ) can you consume?

    Then come back to the thread and lets see what you tttttyytytyyyyyyyypppppyyppepepepppppeeeeee.
     
  16. ohmman

    ohmman Maximum Plaid Member

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    mod note: title amended for clarity.
     
  17. Garlan Garner

    Garlan Garner Well-Known Member

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    NOOOooooo!

    I liked the un-clarity. It was fun.

    ( too much seriousness ) <-----oops did I say that out loud?



    Oh well...let me sneak somewhere else and have a little fun.
    Wishlist / improvements / enhancements (RFEs)
     
  18. SR22pilot

    SR22pilot Member

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    Too bad they can't route some of the current through the heater. That way regen feel could stay constant. I hate when regen doesn't work the same as it usually does.
     
  19. ohmman

    ohmman Maximum Plaid Member

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    There's a balance to be struck in heating the battery for the purposes of regeneration. In most cases, you'd use more energy getting the battery to a state where it can accept "normal" regeneration than you'd ever recapture from the regeneration itself. If it's just the quality of the drive that bothers people, maybe Tesla could introduce some kind of friction brake regeneration "simulator" to appease. But that seems over the top.
     
  20. SR22pilot

    SR22pilot Member

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    Battery? Heck I was talking about heating the car's interior on a cold day but heating the battery would be nice too.
     
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