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Regen in cold climate improvement

Discussion in 'Model S' started by ChrML, Feb 6, 2017.

  1. ChrML

    ChrML Member

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    Just had an idea. Is there a reason regen effect cannot be shalted to a 30 or 60 kW heating element when the battery is too cold to accept power? Then seamlessly transfer to the battery as temperature raises.

    Should offer some goods in cold climates (-20C):
    - Much faster heating
    - Less wasted energy
    - Mire consistent driving experience (same regen at all times)

    Not a California problem, but there are plenty if Teslas sold in cold climate areas.

    Also please add a few components for changing the AC to heatpump :D
     
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  2. whitex

    whitex Active Member

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    Have you considered the size but most importantly the weight of such 60KW heater?
     
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  3. cvrcv

    cvrcv Member

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    Many people have thought of such things. No indication from Tesla on doing something.
     
  4. cvrcv

    cvrcv Member

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    Electric heating elements are very light, and small.
     
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  5. MP3Mike

    MP3Mike Active Member

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    You would also need a heat exchanger big enough to handle that amount of heat getting transferred into the heating/cooling loop, as well as pump(s) fast enough to keep from overheating the liquid. Probably not worth the extra weight/size/cost/complexity...

    How much extra would you be willing to pay if it was added to the "Sub-Zero package"?
     
  6. cvrcv

    cvrcv Member

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    The existing 5kW unit is tiny. No problems adding 3 more of the same units. Or better yet, one unit with a 20kW element.

    Existing coolant pumps can run fast enough to deal with 100kW+ heat loads.
     
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  7. cvrcv

    cvrcv Member

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    $2000
     
  8. MP3Mike

    MP3Mike Active Member

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    How small is tiny? How many cubic inches does the heater, plumbing, and wiring take? (I couldn't find a picture of it.)

    But the OP was asking for the equivalent of 5-11 more of them. And you would want some way to control the heating incrementally, since you wouldn't want the full 30/60kW all the time.
     
  9. cvrcv

    cvrcv Member

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    2014 14 TESLA MODEL S CIRCULATION HEATER HEAT COLLING ENGINE FLUID PUMP | eBay

    Like 2x4x6"
     
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  10. MP3Mike

    MP3Mike Active Member

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    I wouldn't call that tiny. I wonder how much of the already tiny Frunk would go away if you added a 60kW battery heater...
     
  11. David99

    David99 Active Member

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    This has been discussed many times. It would be possible from a technical point of view, but it would take some serious modification and add extra cost and weight. Adding a 60 kW heater would be the easy part. Moving 60 kW of heat is not as easy. The cooling system as it is, is not capable of dealing with such a strong heat source. So you would have to redesign the entire cooling system including the battery to allow a much high flow rate and allow much higher temperatures. You also need some extra electronics to distribute the power between the heating element and the battery.
    So while it can be done it would take some significant redesign and extra cost.
    The gain would be small overall. The battery is only significantly regen-limited when it is cold soaked. That's not a typical, every day situation. When you charge your car at night with the timer so it ends in the morning and preheat it in the morning your battery is actually warm enough to take a good amount of regen. There would be no benefit. The situations where the car was parked in very cold conditions and not plugged in are rare and only then would such a heating element reduce the time for the battery to warm up. When you drive in cold conditions you usually drive very careful and regen would not contribute a large amount of energy. I just think the overall benefit would be very limited and it would be limited to few situations and only to those living in cold climate and only during the winter season. So all in all, I don't think it is worth the effort.
     
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  12. ig_epower

    ig_epower Member

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    Is the present regen at least able to supply the existing 6 kW battery heater and/or the cabin heater if the battery cannot take the charge? Understanding that regen cycles are only brief and momentary but it is power that could be saved nonetheless.
     
  13. Bladerunner

    Bladerunner Member

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    Not to my experience, when the battery is cold soacked you get zero regen, even when the cabin/battery heater is active. I assume the design of how the regen charging works does not allow for other energy flows.
     
  14. David99

    David99 Active Member

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    Unfortunately not.
     
  15. lklundin

    lklundin Member

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    Yes. Think of how hot a good, old 60 W light bulb gets.

    Just cram one thousand of those into your car and you are good to go.

    Any other questions?
     
  16. gearchruncher

    gearchruncher Member

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    Wait, what? At what point does a Tesla generate 100kW of heat that has to be removed in real time?
     
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  17. cvrcv

    cvrcv Member

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    Full throttle. The heat load internal to the battery has been estimated to be over 100kW already, not including invertor and motor efficiency. If you assume both of those are 97% efficient, you get 30kW of heat from those, instantaneous. Of course, at full throttle efficiency is nothing like 97%.
     
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  18. MP3Mike

    MP3Mike Active Member

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    Can you point us to where that has been estimated?

    The max output of the batteries is under 500kW and you are saying that it is loosing another 20% to heat in the battery itself? If that was the case there would be no need for a battery heater, as the battery could create enough heat itself.

    Also, we know the cooling system can't currently keep up with the full heat load.
     
  19. cvrcv

    cvrcv Member

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    Voltage drop * current. 100V drop @ 1500A = 150kW.
    It does. The main point of the system is COOLING. Are you recommending every Tesla owner does 5+ ludicrous launches in a row on a cold battery to warm it up? I should do that immediately after pulling out of my garage on a residential street.

    See above. I was being VERY conservative at using 100kW, since it's greater than an order of magnitude higher the pack heater, should have made the point perfectly. The instantaneous heat load and full power is much bigger.

    You can disagree all you want, doesn't make me wrong.
     
  20. Vitold

    Vitold Active Member

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    #20 Vitold, Feb 8, 2017
    Last edited: Feb 8, 2017
    I think not letting Kinetic energy go to waste (too hot/cold temperatures, battery full) is a next step and will eventually happen. Perhaps instead of powering heating element directly, to make it more universal, Tesla should use an ultracapacitor.

    .5kWh ultracapacitor would cost around $1.5k and it could be charged before battery and stored energy used for heating, AC, added performance, etc.
     

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