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

HVAC (Heater) Really Does Use a Lot of Energy

Discussion in 'Model 3' started by Birdman325, Dec 3, 2018.

  1. Birdman325

    Birdman325 Member

    Joined:
    Aug 15, 2017
    Messages:
    873
    Location:
    Toronto, Canada
    #1 Birdman325, Dec 3, 2018
    Last edited: Dec 3, 2018
    Very unscientific test.
    - I have a LR AWD Model 3 currently running on the 18” Aero winter package.
    - Most mornings I do the same drive - first I drive my son to school, and then I head down to work. The drive from my son’s school to my office in downtown Toronto is apx. 17.6 km (just shy of 11 miles) and is probably net downhill. I also keep the HVAC on manual, fan speed at 2, and temp at 18.5 C (65.3 F).
    - I didn’t drive last Friday but I did on Thursday and the weather was very similar to this morning. Dry and about 4 degrees Celsius (apx 39 degrees F).
    - Driving relatively conservative, I typically can get to an average of about 215- 220 wh/Km on the way down to the office (apx 354 wh/mile).
    - This morning, the only difference was I turned off the HVAC entirely and set the seat heaters to the 2nd level.
    -It definitely was getting uncomfortably “cool” in the car, and the windows (side and rear especially) were becoming quite foggy. But...I ended up pulling into parking with the trip meter showing 119 wh/km! (17.6 km, 37 minutes, 119 wh/km - apx. 191 wh/mile).

    To summarize
    - Using the heater - 220 wh/Km (354 wh/mile)
    - Not using the heater 119 wh/Km (191 wh/mile)

    Granted, this was an extremely off the cuff test, and while I tried to maintain a similar driving style, I was probably 10 minutes earlier than usual, (which for the GTA can make a significant traffic difference). Even accounting for a bunch of those variables, I have never seen a wh/Km figure anywhere near that in the month and a half I have had the car. I know there are lots of posts pointing out how much energy the heating system takes, but I was personally very surprised to see the difference.

    FYI only.
     
    • Like x 1
  2. kwest2

    kwest2 Member

    Joined:
    Apr 28, 2017
    Messages:
    247
    Location:
    Boston, MA
    Sounds about right.
     
  3. absolut20

    absolut20 Member

    Joined:
    Jul 2, 2018
    Messages:
    13
    Location:
    canada
    I'm getting about the same numbers as well. I didn't realize that the winter would cut my range in half. Glad I opted for the LR model
     
    • Like x 1
  4. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Well-Known Member

    Joined:
    Jul 12, 2012
    Messages:
    9,814
    Location:
    Maine
    How long does the driving take?
     
  5. rypalmer

    rypalmer Active Member

    Joined:
    Aug 22, 2014
    Messages:
    1,297
    Location:
    Canada
    It won't.

    This effect is felt more so on shorter drives, not longer drives.
     
    • Like x 7
  6. Reeler

    Reeler Decade of Pure EV Driving

    Joined:
    Oct 14, 2015
    Messages:
    1,718
    Location:
    Denver, CO
    To address this issue, the Nissan LEAF moved to a heat pump to handle AC and heat. They still have a resistive heater for extremely cold temps. Other manufacturers have done a heat pump too. If implemented correctly, it only adds a few parts to the AC system already in the car.

    Sadly, Tesla designs their cars in California for the weather there. Until the agencies that rate MPGe take into account poor HVAC design, lazy engineers will not bother to innovate. In so many ways, Tesla's design is better than the entrenched incumbents except for creature comforts.
     
    • Like x 3
  7. chronopc

    chronopc Active Member

    Joined:
    Jul 8, 2017
    Messages:
    2,873
    Location:
    California
    I only use the seat warmer and I don't notice a real impact to range.
     
    • Like x 1
  8. voip-ninja

    voip-ninja Give me some sugar baby

    Joined:
    Mar 15, 2012
    Messages:
    4,116
    Location:
    Colorado
    See if you're comfortable only using the seat heaters when it's 20F outside.

    Oh, wait, you're in CA like the engineers who designed the car who don't understand cold weather.

    I'm happy with the cold weather performance of this car, but the hit to range during the first 30 minutes of driving if you want cabin heat are pretty substantial. I drove my family about 40 miles on a cold battery on Saturday morning with temps in the low 30's. It was a few separate stops with time for the cabin to get cold each time. Used mileage was about 60.
     
    • Like x 2
  9. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Well-Known Member

    Joined:
    Jul 12, 2012
    Messages:
    9,814
    Location:
    Maine
    The OP is in Toronto, ON.

    The Leaf heat pump is only beneficial down to about 32F/0C.
    The resistive heater would be used for regular cold.

    Other cars have low-temperature heat pumps that can help somewhat down to 14F/-10C.
     
    • Like x 1
  10. Nocturnal

    Nocturnal Supporting Member

    Joined:
    Aug 23, 2018
    Messages:
    5,244
    Location:
    Kansas City
    Cold weather driving can definitely drop the range nearly in half compared to rated range (even on long drives). Granted that also includes the "regular" decreases in range due to driving at highway speeds, wet roads, winter tires etc.
     
    • Informative x 1
  11. chronopc

    chronopc Active Member

    Joined:
    Jul 8, 2017
    Messages:
    2,873
    Location:
    California
    I think the coldest it's been since I've gotten the car was in the high 30s. I was fine with just the seat warmer since I'm usually wearing pretty warm clothing anyways. I'm not sure I can handle being outside int he 20s lol.
     
  12. Nocturnal

    Nocturnal Supporting Member

    Joined:
    Aug 23, 2018
    Messages:
    5,244
    Location:
    Kansas City
    I like to drive without a heavy coat but with a coat the warmer is just fine. I had a long drive in 15 degrees and and I definitely needed some major assistance from the heater.
     
  13. mongo

    mongo Well-Known Member

    Joined:
    May 3, 2017
    Messages:
    12,596
    Location:
    Michigan
    220 Wh/kn vs 119 Wh/km = 101 Wh/km delta * 17.6 km = 1.78kWh over 37 minutes = 2.88kW heater usage. = around 10k BTU. That lines up with ICE heater cores (from super brief search) and seems reasonable, note that the heater output is fairly independent of speed, so slow driving will have a much higher Wh/km impact. 100 kph would produce a 30 Wh/km offset (versus the effective 101 Wh/km for your 28.5 kph drive)
     
    • Like x 1
    • Love x 1
  14. rypalmer

    rypalmer Active Member

    Joined:
    Aug 22, 2014
    Messages:
    1,297
    Location:
    Canada
    Please show me some data where your consumption doubled on a drive over 50km.
     
  15. Birdman325

    Birdman325 Member

    Joined:
    Aug 15, 2017
    Messages:
    873
    Location:
    Toronto, Canada
    This morning it was 17.6 km, 37 minutes, 119 wh/km - apx. 191 wh/mile.
     
  16. DB-Cooper

    DB-Cooper Member

    Joined:
    Oct 29, 2018
    Messages:
    379
    Location:
    Austin, TX
    Stupid question, but how does one turn off the heater completely?
     
  17. Birdman325

    Birdman325 Member

    Joined:
    Aug 15, 2017
    Messages:
    873
    Location:
    Toronto, Canada
    When you press the fan icon and it takes you to the vent direction screen (that is not the right word for it) there is a "power" icon that you can press to turn it off - or on. The temp still shows in your display, but it is greyed out.
     
  18. DB-Cooper

    DB-Cooper Member

    Joined:
    Oct 29, 2018
    Messages:
    379
    Location:
    Austin, TX
    Thanks. I know in ICE cars typically you turn off the fan but the car still heats to wherever the temp is and some air comes in. Clearly not the case here.
     
  19. Nocturnal

    Nocturnal Supporting Member

    Joined:
    Aug 23, 2018
    Messages:
    5,244
    Location:
    Kansas City
    #19 Nocturnal, Dec 3, 2018
    Last edited: Dec 3, 2018
    I don't have data, just my eyeballs. For every mile I traveled I was losing almost 2 miles off my battery range indicator. To be fair the conditions were fairly extreme. 14-15 degrees, wind, heavy snow, some slush on the roads, P3D, 2 seat warmers and cabin heater set to 69. Straight highway running TAC at 65-70. I think people get confused about the range hit because they don't notice their normal range decreases, but do pay attention when the aggregate loss becomes high. This was about 100 miles.
     
  20. MorrisonHiker

    MorrisonHiker S 100D 2020.40.4

    Joined:
    Mar 8, 2015
    Messages:
    8,593
    Location:
    Colorado
    You can also just press and hold the fan icon.
     
    • Informative x 4
    • Helpful x 1
    • Like x 1

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