vfx, I wouldn't throw in that bit about the power required increasing by a factor of eight when speed doubles, because the issue under discussion in the article is range, not power. The Model S has plenty of power...:wink:
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Consumer Reports - Winter chills limit range of the Tesla Model S electric car
- Thread starter CapitalistOppressor
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- Driving Dynamics Model S
Your range depends on how much energy you are using per unit time (power). The more energy you use to overcome drag,
the lower your range will be.
anticitizen13.7
Not posting at TMC after 9/17/2018
This was a good post from Consumer Reports. For an ordinary driver traveling the same route daily, "range anxiety" would not be a problem, because as the CR writer points out, the driver would normally plug the car in when they get home, and even if they forgot, there was a Supercharger nearby.
Yes, energy used to overcome drag is of 4x greater per unit distance (there are also other sources of friction like tire
on road, but this doesn't depend on speed). I didn't intend to confuse the issue! It's just simplest way for me to see that energy used is four times greater for a fixed distance traveled is by calculating energy = power x time and seeing that when speed doubles, the power used goes up by eight and time goes down by two for a fixed distance. If you have another way to see this, that's great!
Very good article IMHO. One comment is that 45F isn't very cold, even for New England. I'd like to see a similar trip below freezing such as is normal around here for Jan and Feb, particularly at night.
I don't agree with some of the comments here that winter driving should be done with a range charge. As the article points out, most people, myself certainly, will be doing range charges very rarely or not all because of the battery degradation warning. It looks like the range estimator on the Tesla site must be assuming a range charge as well since they show over 210 miles for those conditions. It would be nice if the calculator covered lower temperatures and allowed specifying normal or range charge in addition to if the windows are rolled down and the lights on.
The 176 miles he got included an unplugged overnight stop which likely got below freezing and took a significant amount of miles even though some came back. It would be interesting to know what the real range is on a standard charge, driving at 60-65, with the temps around 28-32. It sounds like it would be somewhere around 180 or so before the car read zero, although there might be another 15-20 possible. That would make a trip from Boston to DC pretty tense. The CNN trip was in relatively warm weather and with a range charge so that's not really what I'm talking about.
It seems to me that the bottom line on all this is that Tesla needs to be a little more frank about what the actual capabilities of the car are in cold weather and they desperately need to fix their range estimation software.
I don't agree with some of the comments here that winter driving should be done with a range charge. As the article points out, most people, myself certainly, will be doing range charges very rarely or not all because of the battery degradation warning. It looks like the range estimator on the Tesla site must be assuming a range charge as well since they show over 210 miles for those conditions. It would be nice if the calculator covered lower temperatures and allowed specifying normal or range charge in addition to if the windows are rolled down and the lights on.
The 176 miles he got included an unplugged overnight stop which likely got below freezing and took a significant amount of miles even though some came back. It would be interesting to know what the real range is on a standard charge, driving at 60-65, with the temps around 28-32. It sounds like it would be somewhere around 180 or so before the car read zero, although there might be another 15-20 possible. That would make a trip from Boston to DC pretty tense. The CNN trip was in relatively warm weather and with a range charge so that's not really what I'm talking about.
It seems to me that the bottom line on all this is that Tesla needs to be a little more frank about what the actual capabilities of the car are in cold weather and they desperately need to fix their range estimation software.
I agree. I'm still waiting for my Model S (vin 5476; expected delivery in two weeks), but I currently have a Volt and I notice dramatic changes in the range based on temperature. In the summer, I'd easily get around 45 miles on a charge. In the winter in Chicago, when the temperature is in the mid twenties, the range is more like 26 - 28 miles. This drop off in range is the main reason
I decided to get the 85kW hour battery on my Model S - I assumed that there would be a similar degradation. I'm looking forward to seeing what the actual range is, once I get the car.
I for one would really appreciate it if you'd post your experiences with highway driving in cold weather. I'm assuming that even in March, Chicago will be able to supply some cold temps. :smile:
I live in Milwaukee. My 2012 Volt drops from 48 mile per charge to 30+ in winter. I too got the 85kWh battery for the same reason. Cold weather sucks the power from all EVs. In the case of the Volt and I am sure it will be the same for the MS, heating the cabin uses a ton of power!!!! A/C uses very little power.
My Volt is always plugged in in a garage that never freezes.
The best part about this report is that it suggests that Consumers Reports will discuss the range issue fairly in its full report, eventually. While a good review from CR isn't going to help Tesla much, a bad one could hurt.
Agreed... they also need so stop talking about 300 miles estimated range because it generates a climate of mistrust IMO.
Electric Machete
P#3820
+1
No one is getting 300 miles unless their sole intention is to do so. 200 miles on a range charge would be my limit of comfort and that would be without going over 65MPH.
ChadS
Last tank of gas: March 2009
Hi RDoc. I agree that you don't want to do a lot of range charges. But I still feel that when any source publishes "how far an EV can go" for a long-distance EV (I might agree with you for a limited-range EV like the Leaf), it should include the range number. Just driving around town (when, indeed, they shouldn't do a range charge), nobody cares about the range number, because they're not going to stretch it. When you care is when you are on a road trip, and that is when you do range charge. I don't think (?) anybody was calling for regular range charges; they were just noting that when you care about the top range is for a trip when you will do the range charge.
For the above reasons I like their default, but sure, an option would be nice. Until they add it you can always subtract the difference of 25 miles (the difference will be smaller when consumption is higher, so that's a safe number). I agree Tesla's calculator, while really good for what it covers, should allow lower temperatures - in fact I asked them for that over a year ago. They do have notes on the calculator about windows and lights.
At 65mph in 32 degree weather, consumption would be increased 8% over the baseline 60mph for speed, and 13% over the baseline 70 degree temperature for HVAC. (See numbers HERE). So Rated mile consumption would be 121% of actual miles. So range would be 219 miles (199 miles on a standard charge).
While those numbers are higher than your guess of 180 miles, I think your guess is a lot safer. Standing water would increase consumption by 10%, and colder temperatures, snow or headwinds could increase it still farther. The "safe" number I typically use for accounting for bad weather (or up to 80mph in good weather) is 177 miles - 2/3 of the EPA range.
Thanks for the report. I am a bit surprised at that as I would feel comfortable driving 200 miles on a range charge anytime the temp was above 20. And I am in Minnesota. I am eager to get warmer temps this spring so I can test tis out up here.
Depends on where you live I guess. In Norway in the summer, you'd probably get 300 miles quite easy while following traffic. There is one US Model S in Norway now, not owned by Tesla. The company that owns it just drove Bergen-Hemsedal with the heat on, following traffic. The distance is 182 miles and they had 38 rated miles left. That is a range of 220 miles in 14degF weather, going over a mountain pass in the process and also gaining 3000 feet of net elevation.
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Degradation from range charges are mostly linear with time spent at high SOC. I'm going to do a lot of range charging once I get my S, but I'll be sure to time the charge so it finishes right before departure time.
