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Wow! Temperature Really Does Matter!

Discussion in 'Model S: Driving Dynamics' started by mknox, Apr 23, 2013.

  1. mknox

    mknox Well-Known Member

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    First of all, I'm the kind of guy that actually did get (or even exceed) EPA fuel economy ratings on the ICE cars I drove, summer and winter. I have a long, mostly freeway commute and tended to stick to the speed limit and stayed in the right lane with cruise on. I've been driving my Model S in a similar fashion.

    When I picked my car up in early March, it was unseasonably cool with temps just above or just below freezing for most of the day. This weather carried on for most of March and early April. Even taking it easy on these drives, I was getting well over 600 Wh/mi and sometimes over 750. Nowhere near the 300 (rated) I was shooting for. My lifetime average (I am leaving Trip 2 alone) was somewhere in the 600's. I have about 2,800 miles on the car so far.

    Well, last week we had a freak weather system come through and the temps went up to 85 and a torrential rainstorm passed through. There was even a tornado nearby. That day, driving home at 60 to 65 MPH in the pouring rain, with headlights and a/c on, I was averaging 209 Wh/mi over 30 miles and my projected range was way, way over rated. I wanted to take a picture of the screens with my cell phone, but thought better of it, driving on the freeway in the rain and all. Over the next couple of days it remained warmer and I continued to have no problem beating rated range, getting in the mid 200's even when driving 65 to 70 MPH.

    I guess my point is that I'm surprised that there is THAT much of a difference, and I wonder what a true mid-January Canadian winter is going to look like next year.
     
  2. kevincwelch

    kevincwelch Active Member

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    Noticed this as well.

    My driving habits have been the same to and from work, so it's always stop and go with regen. BUT, how I notice it is in how much range drops while sitting in the garage at work. In the colder temps (<32F), I'd lose a lot of range. I never would see it back, even after heating up and starting to drive. Would always lose it. Above 60F, I lose only a couple of miles over the day. I know range isn't the best gauge of energy loss, but that's how it impacts me practically speaking.
     
  3. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    I'm surprised there is that much of a difference, too. I've driven my S about 7,000 miles in the last six months, right through the Colorado winter. I have never seen even as much as 450 Wh/mi on a trip long enough to fully warm up the pack, and I averaged about 345 Wh/mi during the colder months. Now that the weather is beginning to warm up, I'm down around 325 Wh/mi average for all driving. Some trips I may see under 300, but it's not something I can count on.

    I can't believe the climate differences between here and Ontario account for the difference in consumption; and your driving habits don't sound all that different from mine. I'm in a non-Perf 85 w/ 19" wheels and stock Goodyear all-seasons.
     
  4. mnx

    mnx 2013 P85

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    Egads! Your car is averaging 600Wh/mi over its first 2800 miles? I think that must be some kind of record on here!!!!!

    Note: I got my car February 15 and have averaged 234Wh/km over 4363km. (Using ~62% of the electricity, that your using)

    I was going to suggest that your car sitting in the cold all day had a very large negative impact on efficiency, but you plug in at work right?


     
  5. JerryNycom

    JerryNycom Member

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    I have a house upstate NY thats 199 miles door to door. I REALLY want to take the Model S. I keep reading about the 2/3's rule of 177 miles of range on a max charge. I would be driving about 2 hours of highway (65mph-70mph) and the rest of about hour or so of 55-35mph roads. I have read countless threads about range and speed, ect. but when I drive my car around town locally the range is scary off! Would you take the trip? Also if I feel I might not make it there is NO WHERE to stop and charge. Flatbed to my house would be only option. After reading this post about the weather maybe going on a 70-75 degree day might be my only chance.
     
  6. Doug_G

    Doug_G Lead Moderator

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    If you're getting 600+ Wh/km then the pack heater is running at fairly high power. If you had kept driving for a while the power draw would have dropped as the pack warmed up.

    When it's very cold, you can expect to consume 20% more energy than summer conditions - once things stabilize. If your pack never gets fully warmed up then you'll see huge numbers.

    This is why preheating is so important in the winter.
     
  7. ElSupreme

    ElSupreme Model S 03182

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    Also remember that your Colorado air is REALLY thin to begin with. So having really cold air up there isn't anywhere near as dense as having really cold air at sea level.

    I have noticed a big difference in my energy usage also with the changing temperatures. But I am also driving faster, and with windows down (definitely a efficiency hit at interstate speeds) but still managing the same Wh/mile.
     
  8. Doug_G

    Doug_G Lead Moderator

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    Your trip is doable with care in extreme temperatures, if you (a) Range mode charge just before leaving (so the pack is full AND warm), (b) DO NOT drive at 65 mph, but rather keep it to 55, and (c) be careful and keep a close eye on your range reserve (GPS range - Projected range). I've done very close to the same distance at -20C (-4F) in blizzard conditions, and had a decent safety buffer. See my new blog on road trips: The Rules of Model S Road Tripping - Blogs - Tesla Motors Club - Enthusiasts & Owners Forum

    Piece of cake in the summer. Probably not a big deal around freezing. More of a big deal in extreme cold.

    And yes, upstate NY is something of a charging wasteland. I've noticed more things popping up on plugshare, but it's not clear whether any of them are trustworthy.
     
  9. GeekGirls

    GeekGirls Kid in Candy Store

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    It never gets cold here by Canadian standards, but I honestly haven't found a dramatic difference between 35F and 70F+ ... unless I turn on cabin heat. Relying on heated seats alone during cooler weather kept me comfortable without compromising efficiency. Below freezing I imagine the story changes dramatically, and as things are heating up around here I expect air conditioning will start becoming a factor for me. Above 40F I'd have no concerns about making a 200mi trip with an 85kWh range charge, so long as I didn't have any passengers in the back seats. In colder weather I'd want more experience before deciding what I could do with confidence, and I'd definitely keep my speed down until I was confident I had range to spare.
     
  10. AnOutsider

    AnOutsider S532 # XS27

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    Yup, I was pretty lukewarm on my S when I first got it. As the temps warmed up and I got used to driving it, things have gotten better.

    Would still love a realistic 250-300 miles but it has definitely improved.
     
  11. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    The modestly lower air density at 5,000'-6,000' elevations shouldn't matter much to range: perhaps 5% at the most, given that my average speed is probably in the 30-35mph range. Certainly it's nothing like the difference between 345 Wh/mi and 600+. Pack heating is a candidate for the biggest culprit, like Doug says.
     
  12. lolachampcar

    lolachampcar Active Member

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    Move to Florida.... I almost always get rated range and I like to use my right foot :)

    All kidding aside, thanks for posting real world experiences with the cold.
     
  13. mknox

    mknox Well-Known Member

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    I've actually seen my Trip Odometer go over 1,000 Wh/mi on the "Since Last Charge" screen for the first mile or two. Admittedly, I'm running the HVAC as I normally would have in an ICE, and the pack would have been "cold". It does come down significantly on my hour or so commute, but based on the "Since Last Charge" screen, it was only settling down to the high 500's or low 600's in the cold by the end of my drive. I could do a bit better by triggering the heat and re-starting charging from my smartphone before heading out. I'm just amazed that doing nothing really different (other than using so much HVAC, I suppose) I'm now easily exceeding Rated in the warmer weather.

    I should point out that it has never been a range issue. Even in the worst possible commuting scenario, I don't think I've ever had the battery go below about half (from a Normal, not Range charge). I've got lots of juice to drive as I want, heat and cool as I want with no worries at all. I was really just commenting on the effects of temperature I've seen.

    - - - Updated - - -

    I was born in Ft. Lauderdale, and now my brother lives in LA, so yeah, I hear things like this most of the winter :wink: It is getting nicer here every day, and summers in S. Ontario are actually quite pleasant.
     
  14. brianman

    brianman Burrito Founder

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    I get this daily for the first 1/4 mile or so. Not something I've been overly concerned about. Just sharing the data point.
     
  15. dfitz206

    dfitz206 Member

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    I think it is more the rain than the cold. My range plummets when it rains hard, window fogs up and temperature drops. Temperature hasn't seemed to be as much, but the range of temps here has been 40-55F usually, so don't know that I can speak to that. Hard rain...yes, that hurts range.
     
  16. Al Sherman

    Al Sherman It's about THIS car.

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    Me too.

    Temp has a huge effect, as does running the heat. Just using the seat heaters if possible drops the usage dramatically. Speed is also a large factor. Big difference between 55 and 75mph. However, if you get to the point we're you're puckered about range and are conserving; slowing down considerably makes a huge difference. Like 35-45mph.
     
  17. montgom626

    montgom626 Active Member

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    Cold weather= heater = increased watts per hour. During the mild Spring and Fall, you will get really low watts/hr. AC uses 1/4 the power of the heater (maybe less).

    - - - Updated - - -


    Range charge. Easy drive if above freezing. Have you checked Electric Cars - Charging Stations - Recargo for any J1772 stations???? Also, driving at 35-55 mph really increases range.
     
  18. raymond

    raymond Member

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    I always thought that it was the difference in chemistry of winter and summer fuel. Must be the same for electrons. :rolleyes:
     
  19. greencharge

    greencharge Member

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    Ambient temperature apart, the spike in the wh/mi when the car moves initially affects the various averages and projections . I saw few times up to 400-500wh/mi as I start out of the garage and turn on the street in 30 yards and turn again to another street in 80 yards at crawling pace. As I keep driving the wh/mi cools off to 350's, the best I have seen is 270 wh/mi and that's after good driving behavior with cruise control and no flooring.
     
  20. yobigd20

    yobigd20 Well-Known Member

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    600-750 Wh/mile? sounds like something's wrong. even in 10-20 degree weather, it's hard for me to average above 450Wh/mile when being heavy on the pedal. you should see a 10-20% difference between 20 degree weather and 80 degree weather, not 100+% difference. I'd get that checked out....sounds like something's busted with the batteries' warming pack.
     

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