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
Start a Discussionhttps://teslamotorsclub.com/tmc/tags/

Staying comfortable in Extreme Cold

Discussion in 'Model X: Driving Dynamics' started by Pwdr Extreme, Jan 4, 2017.

  1. Pwdr Extreme

    Pwdr Extreme Member

    Joined:
    Nov 30, 2016
    Messages:
    167
    Location:
    Bozeman, MT
    I'm starting a new thread since this is really about driving in pretty extreme conditions :)

    Car is a new Model X P100DL with 22" wheels.

    Lastnight a friend and I went on a 300 mile road trip at -20 degrees Fahrenheit to deliberately see two things:

    1. Is it possible to stay comfortable without "wrapping up in a blanket"?
    2. Just how much battery power will we use?

    The trip was Bozeman, MT supercharger to Billings, MT supercharger. On the way down temps ranged from -9 to a low of -23, the average was about -14 overall. We left Bozeman at 96% charge with a rated range of 270 miles. 140 actual miles to the Billings supercharger, thus leaving me 130 rated miles of margin. For reference Bozeman is 4800' elevation and Billings is 3100' with 2 substantial mountain passes in between.

    The entire trip we both used our seat heaters set on 1, I turned the steering wheel heat off and on throughout to maintain comfort. (REALLY wish the wheel had a high and low and there was a much easier way to turn it off and on, having to go thru a couple pages on the touch screen is just plain silly)

    Driving speed was 75mph with some areas slowing to 60-65 due to road conditions. Very little wind. On the way down I had cabin heat set to 78, outside air and fan speed set to 9. (Any higher fan speed forces recirculation and instantly fogs the windows). My buddy and I were both wearing jackets, but otherwise not dressed for winter, so to speak. We were both mostly comfortable, but our legs were on the cold side, my left leg especially cold along the driver's door, to the point I was uncomfortable. So my initial thoughts were if I had brought a blanket to lay across my legs, I would have been completely comfortable, my buddy agreed. Conclusion, having to use a blanket in a $120,000+ car shouldn't be necessary, but given the fact that 20 below is pretty extreme conditions, it's certainly not the end of the world and acceptable. I have driven in even colder conditions in numerous ICE vehicles and not even needed my jacket for reference. So the conclusion is the heater is barely adequate at best, but at least it's "doable" to drive in the cold.

    When I arrived I had 21 rated miles left, so I used 249 rated miles to drive 140 actual miles, average was 584 wh/mi. You'd better have PLENTY of excess range stored up before setting out in these conditions.

    Now the return trip...

    Charged to 95%, 267 rated miles range.

    Temps were more consistently in the -20 range, with a low of -27. I'd say the average was pretty much -20. Heater set to the same level. We were both uncomfortable, our legs were cold, so that little bit of difference was definitely the breaking point and had surpassed the limits of the heater. Well at least now I know. Then I got the idea to install the sun shade on the upper half of the windshield. What a difference!!!! It hangs down maybe an inch or so from the glass creating just enough air space for an insulating pocket. Holding our hands a few inches below the glass before we could definitely feel very cold air dropping from the glass and landing right on our legs. After the sun shade we couldn't feel the cold air. 20 miles later our legs were warm and we were both completely comfortable. Great! However, about 40 miles in to the trip I started getting the slow down messages, decided there is no way to make Bozeman unless we either drastically slow down, or lower the temp back to the uncomfortable range. Stopped at the Big Timber supercharger 60 miles from Bozeman instead. Drove only 80 miles, used 165 rated miles. 698 wh/hr. Climbing definitely was hurting us. Arrived back home safe and sound in Belgrade with an average usage for the trip at 630 wh/hr.

    So overall what I learned is the sun shield makes a HUGE difference (I have the evanex insulation panel I'm going to install between the window and sunshield and try again tonight) and you'd better have at least twice your actual distance in rated range available to make it. My car is a 90D with 20" wheels once I receive it, so my actual driving distance is probably pretty close to the P100D with 22's, if not slightly better.

    Again, the point of this wasn't to see "how far we could go if we have to" it was to see how the car would work in very cold conditions without making any sacrifices to comfort or speed. Obviously I know if I had slowed down, wrapped up in blanket and put on gloves and a hat I could have driven substantially further, but I didn't buy a $120,000 car to not be completely comfortable driving it the way I want. =)

    Oh, I want to add for the last 10 miles of the trip I jumped in the middle row of this 7 seater. Very comfortable temperature wise, but the right side of my face so close to the window would have probably started to get uncomfortable after several more miles. The 6 seater, which is what I ordered seems to have the outer seats set closer to the middle, I didn't remember my shoulders actually being against the door when I set in the back of the showroom 6 seater, I hope this is the case.
    The rear heater is a joke, we turned it up 80 degrees and turned the fan speed down to 3 so it wasn't blowing too hard, the air coming from the vents was Luke warm at best, I'd estimate 70 degrees or so. Any higher fan speeds and the volume of air actually made it colder. Fortunately in the middle row I was very comfortable just from the front heater. Not sure what the 3rd row would be like.

    So there you have it, cheers! =)
     
    • Informative x 30
    • Helpful x 3
    • Like x 2
  2. rhumbliner

    rhumbliner Member

    Joined:
    Sep 24, 2015
    Messages:
    299
    Location:
    Las.Vegas Jackson.Hole Fish.Creek
    Thanks for doing this experiment. Very informative.

    I've done a similar experiment driving between Idaho Falls and Jackson, over the Teton Pass in my S90D with 19" tires. The latest drive predicted that I would use 26% of my battery charge but I ended up using 44%. The temp was around -10° much of the distance, so not as cold as your test, but I don't have the sub-zero package so there was no heat to the steering wheel. I drove at or just just above the speed limit whenever possible and there was no wind. We had both seat heaters set to 1 and cabin temp set to 60° but we were dressed fairly warm and I typically wear driving gloves. We were just on the inside edge of being comfortable but we also noticed that our outside legs were little too cold.

    I agree ambient air temp makes a huge difference in our range.
     
    • Like x 3
    • Informative x 2
    • Helpful x 1
  3. Pwdr Extreme

    Pwdr Extreme Member

    Joined:
    Nov 30, 2016
    Messages:
    167
    Location:
    Bozeman, MT
    Tonight I went for another drive, this time I had my insulated windshield piece installed between the window and the sun shield, this is definitely the way to go. I was quite comfortable and actually able to lower the fan speed. Outside temps were ranging between -11 and -25, so very similar conditions.
     
    • Informative x 3
    • Helpful x 1
    • Like x 1
  4. Magoo406

    Magoo406 Member

    Joined:
    Dec 22, 2016
    Messages:
    8
    Location:
    Montana
    Thanks so much for the post! I have been trying to understand the recent and current extreme weather conditions affecting performance and range. I have an MS P100D being built! Waiting for delivery.
     
  5. CSFTN

    CSFTN Member

    Joined:
    Aug 24, 2014
    Messages:
    646
    Location:
    Memphis, TN
    Interesting data points .. your legs were cold, seat heater on the lowest setting while still being on? Interesting experiment .... just checking but you're aware the most efficient method to keep warm is seat heater to max you're comfortable with, cabin temp closer to 70 than 80? Also, try leaving the climate control on Auto but AC off? Last point is a real question, I have no idea how auto works when its subzero cold.

    No flame wars intended ...
     
    • Like x 2
  6. Pwdr Extreme

    Pwdr Extreme Member

    Joined:
    Nov 30, 2016
    Messages:
    167
    Location:
    Bozeman, MT
    CSFTN, no offense taken whatsoever. I'll explain in more detail. My left knee was cold enough it was starting to ache, the tops of my legs and both knees were uncomfortably cold, my buddy said the same thing. The part of our body that was touching the seat was quite warm due to the seat heaters, my upper body was very comfortable. Perhaps you haven't had the opportunity to experience very cold weather driving, so I'll elaborate on the heating system. Auto does NOT work as auto does in any other car I've owned, which I'm guessing you are comparing it to. In my Mercedes, Audi's, etc. I would just set it to 70 and forget it. In fact today driving my pickup at -8 I did exactly that, just set it to 70 auto and all was well. If you do that in the Tesla two things happen, 1 the windows will fog instantly because it puts it in recirculation mode, 2 although it may say 70, the actual temp is nowhere near that. I had to keep cranking it up to get heat while going down the highway. I found this exact same scenario in the Model S I just took a 6k road trip in. While driving I would have it set around 76 to be comfortable and when I'd pull in to charge I'd have to lower to 68-69 to keep it from getting to hot. My guess is the sensor is somewhere in the cabin that doesn't compensate for the tremendous amount of heat loss through the windows while traveling at 70+ mph in below freezing weather.

    And yes, like I stated I'm aware there are more energy efficient methods, but that involves some discomfort. The seat heaters won't keep my arthritic knee warm (dislocated it 4 times during sports, etc.) do absolutely nothing for my feet, and don't keep my nose and ears toasty. :) Setting 3 on the heaters is great when you're freezing, but quickly becomes too hot. Setting 2 gets to be a touch warm after 50-100 miles, and setting 1 I have found to be perfect for long distances.

    My whole point wasn't to see what could be done to maximize range and such in the winter, but more to see what would happen if I treated it like my Mercedes. Toasty warm in below zero weather while driving interstate speeds. And yes, it is possible, but you need to insulate the upper glass, learn how to manipulate the HVAC system, and you'd better plan on using twice the rated range. :)
     
    • Informative x 7
    • Helpful x 1
    • Like x 1
  7. Pwdr Extreme

    Pwdr Extreme Member

    Joined:
    Nov 30, 2016
    Messages:
    167
    Location:
    Bozeman, MT
    Awesome! I see you're in Montana as well, what part? They told me there are only a handful of MX's here in Montana, I very seriously considered the P100DL, they said there would only be 1 other one here that they knew of, must be yours!
     
    • Like x 1
  8. K-MTG

    K-MTG Sunshade Captain of TMC

    Joined:
    Oct 24, 2015
    Messages:
    4,118
    Location:
    Irvine, CA
    Sunshade to the rescue!!!!!

     
    • Funny x 3
    • Like x 1
  9. andrewket

    andrewket Well-Known Member

    Joined:
    Dec 20, 2012
    Messages:
    5,593
    I've only driven in the extreme cold you're talking about once, so my comments should be taken with a grain of salt.

    1. 90D will get better range than a P90D every day
    2. Good choice on 20" wheels. The 22's come with a 10% efficiency penalty.
    3. Use the electric seats and wheel as much as you want. Their energy use is a fraction of the cabin heather.
    4. 78-80F is hot. This is what you needed to set to get comfortable?
    5. On my trip, I wrapped myself in an 12v electric blanket. Cheap on Amazon. This allowed me to keep the cabin heater low.

    Thanks for the advice on the sunscreen. I wouldn't have thought of that one.
     
    • Like x 1
  10. ecarfan

    ecarfan Well-Known Member

    Joined:
    Sep 21, 2013
    Messages:
    13,588
    Location:
    San Mateo, CA
    @Pwdr Extreme explained that in his post #6 just a few hours before your post.

    He is driving in extreme conditions, at least by most people's standards. Since EVs do not have the luxury of large amounts of waste heat from an ICE, it is more challenging to keep the cabin warm. It appears to me that following his advice, as well as wearing additional clothing, is desirable.
     
    • Like x 1
  11. jaguar36

    jaguar36 Active Member

    Joined:
    Apr 10, 2014
    Messages:
    1,302
    Location:
    NJ
    Any idea what the cabin temperature actually was? Be interesting to see if you set the heater for 78F if it actually gets to that temp.

    Also, how fast were you going? I've found evtripplanner to be quite accurate in 'normal' conditions, however assuming you were going around 80mph, it doesn't appear to be accurate at all at that temp (which isn't surprising to be fair). It shows a wh/mi of 419 for Bozeman to Billings.
     
    • Like x 1
  12. andrewket

    andrewket Well-Known Member

    Joined:
    Dec 20, 2012
    Messages:
    5,593
    Understood that there is no waste heat. However, it's a thermostat. I want the temperature to be x degrees. Do what you need to do to make that happen. If I'm setting it to 80F, either I really like it hot, or the temperature differential between the air next to the thermostat and other parts of the car is far off, sufficiently enough to make the other areas uncomfortable. That's a big delta. This may very well be what is occurring to with these extreme conditions. As I said in my post, I think I've only ever driven my S in below 0 degree F weather once or twice.
     
  13. Pwdr Extreme

    Pwdr Extreme Member

    Joined:
    Nov 30, 2016
    Messages:
    167
    Location:
    Bozeman, MT
    I typically set all of my ICE vehicles to 69-70 in the winter, so assuming their thermostats are accurate, I would say the Tesla interior was probably 68-69 degrees. Pretty much the same temperature if not maybe slightly colder than what I'm used to. I was driving 75mph probably 80% of the time and slowed down to 60-65 the rest of the time due to road conditions (light snow pack & icy)

    Like I said in an earlier post, that is what it took to get the car to produce enough heat to be comfortable. When I pull in to charge I lower it to 69 (and put the fan back on auto) to be comfortable. This tells me the sensor is somewhere in the car in an area that doesn't experience the extreme heat loss through the windows while going down the highway. And it is certainly exponential. In 32 degree weather, a setting of 72 is comfortable (still lowering it while charging) as it gets closer to 0, I need to turn it up to 74, once it drops below zero, I need to turn it up to 76 ultimately landing at 78 when it's -20. (Also needing to manually turn up the blower speed concurrently with the temp settings). This is maintaining pretty much the same cabin temperature the entire time.

    Again, I completely agree the thermostat should maintain the temp regardless of outside temp as most ICE vehicles do, the Tesla, however, I can assure you does not.
     
  14. K-MTG

    K-MTG Sunshade Captain of TMC

    Joined:
    Oct 24, 2015
    Messages:
    4,118
    Location:
    Irvine, CA
    I have no idea if the heat on my X even works, I am in SoCal thus I am still running the AC
     
    • Funny x 3
  15. Ambidexter

    Ambidexter Member

    Joined:
    Nov 14, 2016
    Messages:
    100
    Location:
    Los Gatos, CA
  16. CSFTN

    CSFTN Member

    Joined:
    Aug 24, 2014
    Messages:
    646
    Location:
    Memphis, TN
    Thank you for the detailed response. It is very informative. Along those lines, trying to tease out causes and effects: were any of these other ICE vehicles you have driven in this -20degF weather (God that must be cold) 100% Aluminum? I believe aluminum is the second best metallic conductor of heat, surpassed only by copper. So, its fundamentally problematic . Audi A8, newest Ford F150? What else is all aluminum? Isn't there a Jag too?

    I think it is likely Tesla never did extreme cold testing on this body, unless Mercedes-Benz did it for them (Mercedes owned 20% of Tesla when the Model S design was being completed) so it wouldn't surprise me if the S and to a slightly lesser extent the X isn't all that good in the extreme cold. Sounds like the HVAC logic needs an extreme cold update at the very least. so it more closely emulates the settings you have described.
     
  17. Pwdr Extreme

    Pwdr Extreme Member

    Joined:
    Nov 30, 2016
    Messages:
    167
    Location:
    Bozeman, MT
    That's an interesting point, I know my Corvette is mostly aluminum, but it doesn't see that kind of weather. My Audi's (A6, A4, Q7), and Mercedes (S55AMG, S550, SLK) used quite abit of aluminum but were not all aluminum. I agree, the HVAC logic could use some updating.
     
  18. TLej

    TLej Little-Known Member

    Joined:
    Dec 29, 2015
    Messages:
    149
    Location:
    Edmonton, Alberta, Canada
    @Pwdr Extreme Curious, what was your setting for where the air should be blowing? Feet, dash vents, windshield, or some combination of the three?
     
    • Like x 1
  19. Pwdr Extreme

    Pwdr Extreme Member

    Joined:
    Nov 30, 2016
    Messages:
    167
    Location:
    Bozeman, MT
    [​IMG]

    It was a little colder today, but it was bright and sunny. Left my garage in Belgrade which was 40 degrees inside headed to Livingston 37 miles and one mountain pass away. 237 rated miles at 80% charge. 19 miles later I had used up 16% of my battery, or about 60 rated miles. This is how long it took the car to heat the battery pack to the point the dashes were gone limiting the regen. I was using about 790 wh/mi and hadn't even began the climb yet. Heating the battery requires a tremendous amount of power it seems. On the bright side, due to the sun shining in the windows allowing for some passive heating, I was able to lower the cabin temp down to 76 and set the fan to auto which selected a speed of 7. I tried full auto HVAC and of course it turned on recirculation and instantly fogged the windows. On the way home after the car had sat outside for several hours in -5 weather, it took 30 miles before the battery was fully warmed up. Outside temps finally had moved to the positive side, it was now 1 degree. I stopped at the Bozeman supercharger with a total drive of 68 miles, yet I chewed through 150 rated miles of power. Moral of the story, when you add in a cold battery to the mix, range REALLY suffers. (My previous tests were all right after leaving a charger so the battery was warm)

    I think that's about all the testing I'm going to do, unless somebody has any specific questions, tomorrow is supposed to finally start warming up around here.

    Hope this info has helped! :D
     
    • Informative x 4
    • Like x 2
  20. Pwdr Extreme

    Pwdr Extreme Member

    Joined:
    Nov 30, 2016
    Messages:
    167
    Location:
    Bozeman, MT
    Feet and windshield during my night drives, the day drive was feet only 1/2 the time and feet and windshield the other half. Oddly enough we found our legs were actually colder when we selected feet and dash wrongly assuming this would make our bodies the most comfortable.
     
    • Informative x 2

Share This Page