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
  1. TMC is currently READ ONLY.
    Click here for more info.

Why does Tesla use a Resistance Heater instead of Heat Pump

Discussion in 'Model S' started by GJ79, Feb 1, 2017.

Tags:
  1. arnis

    arnis Member

    Joined:
    Apr 13, 2015
    Messages:
    919
    Location:
    Estonia
    #581 arnis, Mar 23, 2020
    Last edited: Mar 23, 2020
    I didn't expect Tesla to update their HVAC on Y but they did.
    MP3Mike, mongo, StealthP3D who all "disagreed" with anything I said are switching sides unnoticeably :D

    That "windings inefficiency blabla" is "inventing a bicycle" story. (PS: Google calls FSD computer "Autopilot", hmmm)
    As a heavy HP user, I tell you guys, that at -12*C HP automotive compressor is running really hard and
    using at least 1kW of electricity. That electricity "magically" turns into heat. So 1kW of energy used by compressor
    will still be able to generate around 1.3-1.6kW of heat. In addition to PTC that will definitely still be available on Model Y.
    If I worked at Tesla, I would still experiment with exhaust port(s) radiator(s) for heat scavenging. These ports are
    behind the rear bumper for most vehicles. And of course use coolant from drivetrain as refrigerant "afterheater"
    right after refrigerant passes external heat condenser and before it enters compressor in HEAT loop.

    Like I said before I will say again. -20*C is rare - Wisconsin or Norway. No need to go crazy with optimization for these conditions.
    Also air is very dry at these temps and heating requirements (per one extra degree) go down compared to -5*C.


    As of right now Model Y should be "good performer" in cold climates. Compared to S or even 3 - those are "one of the worst".
    Biggest Winter Range Test Ever Reveals Best EVs For Cold Weather
     
    • Like x 2
    • Disagree x 2
  2. MP3Mike

    MP3Mike Well-Known Member

    Joined:
    Feb 1, 2016
    Messages:
    14,925
    Location:
    Oregon
    Nope, there is no PTC heater in the Model Y.
     
    • Like x 2
    • Disagree x 1
  3. dgpcolorado

    dgpcolorado high altitude member

    Joined:
    Apr 25, 2015
    Messages:
    2,475
    Location:
    The Western Slope, Colorado
    Right, if the patent listed in Mongo's post 556 is the system used in the Model Y, no separate PTC heater is needed.
     
    • Like x 1
  4. mongo

    mongo Well-Known Member

    Joined:
    May 3, 2017
    Messages:
    12,857
    Location:
    Michigan
    It is also not listed in the HV components for the Y. SmartSelect_20200323-115711_Adobe Acrobat.jpg
     
    • Like x 2
  5. TimothyHW3

    TimothyHW3 Member

    Joined:
    Jun 2, 2019
    Messages:
    944
    Location:
    Germany
    Will the heat pump also warm up the battery instead of the stators on the motors? This will not only decrease heat usage, but also greatly improve "standby drain", especially while driving to Supercharger or when preheating the car. The current Model 3 Dual Motor uses up to 7.5kW from both motors just to heat up the battery. This is huge if they can lower that!
     
    • Like x 1
  6. mongo

    mongo Well-Known Member

    Joined:
    May 3, 2017
    Messages:
    12,857
    Location:
    Michigan
    Yes, the more complex version called out in the patent does that.
     
    • Informative x 1
  7. TimothyHW3

    TimothyHW3 Member

    Joined:
    Jun 2, 2019
    Messages:
    944
    Location:
    Germany
    Is there a way to get a confirmation? Do we have someone with OBD II adapter and Model Y to tell us what happens with the stators when you preheat the car? That will be interesting.

    I would assume they would use it to heat the battery but who knows? Is the heat pump very loud? I remember the Renault Zoe was very loud.
     
  8. MP3Mike

    MP3Mike Well-Known Member

    Joined:
    Feb 1, 2016
    Messages:
    14,925
    Location:
    Oregon
    I imagine that Tesla will use whatever they feel is necessary. If you have a "frozen" battery and plug in at a Supercharger it will likely use both motors and the heat pump to get the battery up to charging temperature as quickly as possible. Is there a reason you don't want them to use the motors for heat? (If it is really cold the heat pump only operates at a COP of 1, so I doubt it would be any more efficient than the motors.

    It doesn't seem to be any louder than the AC system on the Model 3. There is a video on YouTube where someone turned it on and was outside to listen.
     
  9. TimothyHW3

    TimothyHW3 Member

    Joined:
    Jun 2, 2019
    Messages:
    944
    Location:
    Germany
    The motors' stators are very inneficient. 7,5kW is a lot. If the heat pump runs at 7.5kW even at 1 COP it is still better than the stators. But most of the time it will be at least around 2. Also using the motors, it makes noise and while overall a good workaround, I would like a dedicated system that doesn't involve the stators for something other than driving to reduce the workload on the drive unit. It is still an expensive thing to repair.

    Can you link me to the video with the noise test? What was the outside temp? It should be in your Youtube history or at least the channel name?
     
  10. MP3Mike

    MP3Mike Well-Known Member

    Joined:
    Feb 1, 2016
    Messages:
    14,925
    Location:
    Oregon
    How is the motor using 7.5kW to produce nothing but heat less efficient than the heat pump running 7.5kW at a COP of 1 to produce heat?
    In both cases 100% of the electricity is getting converted into heat. (Maybe more of the heat gets lost into the environment from the motor casing and coolant lines, but I doubt it is a significant difference.)

    It is buried somewhere in this long video:

     
    • Disagree x 1
  11. TimothyHW3

    TimothyHW3 Member

    Joined:
    Jun 2, 2019
    Messages:
    944
    Location:
    Germany
    #591 TimothyHW3, Mar 27, 2020
    Last edited: Mar 27, 2020
    Because the heat pump will not use 7.5kW and in most cases will run at 2 -2.5COP.
    When I said it is better at 1 COP I meant to say that I prefer the heat pump to run isntead of the complicated and expensive DU that is needed to move the car around.

    Plus I am not quite sure wether the heat from the stators is at 1 COP, I am pretty sure there are more losses on the way to the battery.

    Ok I heard it, but was on high - it was quite loud actually. I guess we have to wait and see.
     
    • Like x 1
  12. arnis

    arnis Member

    Joined:
    Apr 13, 2015
    Messages:
    919
    Location:
    Estonia
    Correct. Heating motors and then transporting heat has lots of losses on the way (especially when driving) and on the way back to motor. Also motor itself cools down (made out of metal). In case of those 'good ol' 0F cases' everybody is so happy to tell here, losses can be way more than 20%, depending on speed/wind.
    This is why EVs with external cabin heating units have significantly lower efficiency (than 100%) compared to HVAC PTC units.
    HP efficiency in real weather never drops to (or near to) COP1.0. It also depends on refrigerant that is used in the system and HP compressor design (how many stages of compression).

    HP in heating cycle makes more noise than in cooling cycle (including fans) if load is equal (for example, 1kW).
     
  13. Lon12

    Lon12 Member

    Joined:
    Oct 12, 2015
    Messages:
    831
    Location:
    Calgary, AB, Canada
    So I see from Munro's latest video that Model Y owners are already complaining about the noise of the heat pump and that Tesla will be installing a noise cover on it soon.
     
  14. AWDtsla

    AWDtsla Active Member

    Joined:
    Mar 3, 2013
    Messages:
    4,262
    Location:
    NE
    The story here is Tesla shipped cars to customers with pieces missing. Surprise Surprise.
     
    • Like x 1
  15. mongo

    mongo Well-Known Member

    Joined:
    May 3, 2017
    Messages:
    12,857
    Location:
    Michigan
    May not be that simple, some Y are quiet:
    Heat Pump Sound Issue?
     
    • Informative x 2
  16. InternetDude

    InternetDude Member

    Joined:
    Nov 5, 2014
    Messages:
    782
    Location:
    Yes
    Nothing is more important to Tesla than delivery #s.
     
    • Like x 1
  17. arnis

    arnis Member

    Joined:
    Apr 13, 2015
    Messages:
    919
    Location:
    Estonia
    My eye-measurements say that cover was not planned. There is no space for 2-3cm cover over compressor. So they will have to "get creative" with that insulation.
     
  18. Candleflame

    Candleflame Active Member

    Joined:
    Mar 9, 2015
    Messages:
    2,368
    Location:
    QLD, Australia
    I believe a lot of the reason is that Teslas are cars made by desert people for the desert. Didn't they mess up the initial headlight washers or smth because theyd freeze in the cold and the engineers didnt consider that. Tesla probably does attract some talent but I doubt many engineers are from cold regions.

    A good example of the other way around are older BMWs in the desert - I know BMW usually tests their cars in the USA for heat and low quality fuel tests but certainly with the E46 3 series and the equivalent 5 series they didnt engineer the offgassing smell very well - not very pleasant lol.
     
    • Like x 1
  19. wws

    wws Member

    Joined:
    Aug 11, 2014
    Messages:
    854
    Location:
    Northern California
    Well GM and Ford haven't used heat pumps either - and they are in Michigan. So go figure.

    (Historical note: 25 years ago, GM did use a heat pump in the EV1.)
     
    • Like x 2
  20. Matias

    Matias Active Member

    Joined:
    Apr 2, 2014
    Messages:
    3,208
    Location:
    Finland
    Heat pump solution is not without issues. More specifically apparently Tesla draws heat from the battery too much and it affects cold weather performance in the new Model 3 performance.

     
    • Informative x 3

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