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

Outside temperature accuracy

Discussion in 'Model 3' started by funchess, Jun 8, 2018.

  1. ZOMGVTEK

    ZOMGVTEK Member

    Joined:
    May 19, 2015
    Messages:
    557
    Location:
    'Merica
    #41 ZOMGVTEK, Jul 19, 2019
    Last edited: Jul 19, 2019
    I don't suspect the car is reading the temperature wrong. It's more likely reading the temperature within 1-2 degrees of wherever the sensor is placed. This can be very different from the air temperature at times. Cars typically have some basic logic to minimize the error, but they all do this differently and its always an estimation. Some ICE cars hold the last reading from shutdown until the coolant temp drops below a certain value, since they know the hot engine is going to screw with the reading until it all cools down. Often the response is slowed so you don't get wild spikes, but you also don't get a true reading until some time has passed.

    If you put a thermometer outside in the sun, it will read higher than the air temperature. This is not an invalid reading, its just telling you the temperature of the thermometer itself. There's really nowhere on a car you can put a sensor to get perfect air temperature readings, its a ballpark unless you're driving for a bit at decent speeds. If the car is parked, has been parked recently, has surrounding heat sources, or is moving slowly, it will be wrong. I don't see what Tesla can do about this other than just 'adjust' the reading. And then when its not in sunlight it will be reading low. They probably could get some advanced adjustments based on assumptions and other sensor data. But this is just a guess and it will still be wrong. I'm guessing they're just displaying the buffered sensor reading. Most cars are not very accurate. I'd guess Tesla has a very crude filter on the readings that hasn't been optimized. It's very likely they're well aware of this.
     
  2. lolder

    lolder Member

    Joined:
    Jun 11, 2016
    Messages:
    856
    Location:
    SW Florida
    My temperature reading has always been correct.
     
  3. travis1906

    travis1906 Member

    Joined:
    Feb 12, 2019
    Messages:
    86
    Location:
    Haymarket, VA
    Concur with the sentiments on the thread. Always much higher than actual temp outside. Not unusual for it to read 100 or higher and actual temp is not like 90 to 95. None of my other cars ever had this issue. Temp reading was essentially the same as the actual temp outside confirmed with multiple sources (phone app, temp readings on digital signs at banks, etc)
     
  4. RScottyL

    RScottyL Member

    Joined:
    Dec 19, 2016
    Messages:
    268
    Location:
    Arlington, Texas
    I have seen this on many different cars when it has been sitting!

    Once you get in and start driving, it will normal out!
     
  5. richtrav

    richtrav Member

    Joined:
    Apr 20, 2019
    Messages:
    130
    Location:
    South Texas
    While not 7-10 degrees off, mine usually runs about 3-5 degrees too warm. As an informal test I have called a friend who is driving the same road right behind or in front of me and the reading on their car is at least 2 degrees cooler. It seems to be off more when the sun is out.
     
  6. lolder

    lolder Member

    Joined:
    Jun 11, 2016
    Messages:
    856
    Location:
    SW Florida
    This year has been warmer in SW Florida than any of the last 40 ! Usual temps are 92-95 and this year they are 95-98. I have two outside thermometers on my home on either side and note the lowest one. When I arrive home the M3 temperature agrees with them. I have seen 102 out on local highways that I have never seen before. This year is warmer all over the US and when the sun is shining on highways and there is little breeze, I believe the M3 readings are correct.
     
  7. Leafdriver333

    Leafdriver333 Somewhat Active Member

    Joined:
    Mar 21, 2019
    Messages:
    1,070
    Location:
    usa
    Mine is always higher also
     
  8. VanillaAir_UK

    VanillaAir_UK Moderator UK and Ireland

    Joined:
    Jun 17, 2019
    Messages:
    5,756
    Location:
    Surrey, UK
    Never had a car that had a remotely accurate temperature sensor when left stationary in hot weather, in or out of the sun. You only need to start moving and it all changes.

    They appear much more accurate at colder temperatures, especially close to freezing, when knowing the outside temperature is much more important to me.
     
  9. Big Dog

    Big Dog Active Member

    Joined:
    Mar 7, 2016
    Messages:
    1,392
    Location:
    Irvine, CA
    As a former STEM major, I get all that, and that is why in my earlier post, I only referenced deltas in the shade/cloudy day, so direct solar warming would not be a factor. My last two cars were generally within a couple of degrees of the surrounding temp; since both cars were 20+ years old, this is not exactly new technology stuff.

    Obviously, not a big deal, but I only raised the question to others to help me understand if it was only my sensor that was off and needed to be replaced by the SC or, if that was just the way it is with other Teslas due to design/sensor placement. The latter appears to be the case.
     
  10. lolder

    lolder Member

    Joined:
    Jun 11, 2016
    Messages:
    856
    Location:
    SW Florida
    I say again, mine is dead on.
     
  11. LakeWorthB

    LakeWorthB Member

    Joined:
    Jun 3, 2019
    Messages:
    93
    Location:
    Lake Worth, FL
    Officially the temperature stated by the weather service is with a thermometer in shade at least 6ft above grass. Any sun or heated car/asphalt will affect temp readings, so it is more surprising that it ever matches.
     
  12. GolanB

    GolanB Supporting Member

    Joined:
    Sep 22, 2018
    Messages:
    618
    Location:
    NYC
    From what I understand, the temperature sensor is located near the passenger side wheel well behind the front bumper. Someone had posted this video earlier of a front pumper disassembly and claimed it could be found here.

     
  13. jebinc

    jebinc M3 LR AWD w/FSD and white premium interior

    Joined:
    Jun 19, 2019
    Messages:
    3,402
    Location:
    Seattle area
    If true, would the sensor pick up heat coming off the tire - especially if driving was "spirited"?!
     
  14. GolanB

    GolanB Supporting Member

    Joined:
    Sep 22, 2018
    Messages:
    618
    Location:
    NYC
    Yesterday during the heat-wave I saw one of the highest recorded temperatures on my Tesla (104F Outside, 133F Inside).

    Screen Shot 2019-07-22 at 12.50.36 PM.png

    I enabled cabin-overheat protection and its now keeping the cabin around 100 degrees. I'm already using sun screens for the top and rear windows, and will probably pick one up for the front windshield this week. They make a huge difference. I'm mostly concerned about electronic component and surface damage. I have heard of cases of warping and bubling of the dash surface.

    Screen Shot 2019-07-22 at 12.54.45 PM.png
     
  15. Mikeydeek

    Mikeydeek Member

    Joined:
    May 8, 2018
    Messages:
    141
    Location:
    Ottawa
    As the temps are getting cooler now, I notice mine is showing around 4-5 degrees C warmer. This morning was 3 degrees on accuweather/weather network/radio and around 7-8 C on the car display.

    However when I look at my trip reports on Tezlab, it shows the temperature the same as accuweather etc. Not sure where Tezlab is getting its temps from, but I assume from the car database somewhere? ...
     

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