6 ms·

Tesla vs NY Times: A deeper look at the data

17 points by dsberkholz 14y ago

msrpotus 14y ago
Anyone know if that's typical for batteries in cold weather or is Tesla's exceptionally bad?
- potatolicious 14y ago
  Not all batteries - but lithium batteries in general are known for greatly reduced performance in the cold. Take your camera out in the winter some time and you'll find that it'll drain several times faster than normal. I read a recent interview with a well-known landscape photographer who shoots in the Arctic - he carries a whole bandolier of batteries, kept close to his chest at all times to keep them warm. Apparently in the extreme Arctic cold the batteries are reduced to literally a few dozen shots before dying.
cryptoz 14y ago
This isn't a deeper look. It's a shallower look. Didn't Musk say that the estimated range is dependent on speed, and that Broder sped illegally fast for part of the trip? There are other factors, as well. There may well be something to say about Tesla's estimations being off, but this isn't it.
- freyr 14y ago
  "Didn't Musk say that the estimated range is dependent on speed" Did he? Because from this figure, it appears the estimated range is NOT dependent on speed (as, of course, it should be). Notice that the lines are extremely linear, with identical slopes throughout. If he sped for part of the trip, why don't we see steeper slopes during those times? So Broder "sped illegally fast." What does this even mean? The speed limit is 55 mph on most highways, but nobody goes at that speed. Can the Tesla range estimator not acknowledge speeds about 55 mpg?
  - loeg 14y ago
    > The speed limit is 55 mph on most highways Really? In this part of the country (pacific northwest) the speed limit on interstates is 60 mph in the city and 70 mph in the country.
    - freyr 14y ago
      You're right. It looks like 65-75 is common throughout the country. Guess I haven't looked at a posted speed limit in a while.
rgovostes 14y ago
What the article is explaining can be summarized in this chart: http://i.imgur.com/mNcGdfS.png http://i.imgur.com/mNcGdfS.png But I think this is incorrect: > In nearly every case, the Tesla gets about 20% fewer miles out of each charge than it estimated. Musk and Broder 'agree' that the vehicle's actual range was greater than it estimated. Musk's wrote, > Then he bizarrely states that the screen showed “Est. remaining range: 32 miles” and the car traveled “51 miles," contradicting his own statement... The car actually did an admirable job exceeding its projected range. As an aside, please disable Tynt on your blog.
- dsberkholz 14y ago
  > What the article is explaining can be summarized in this chart: http://i.imgur.com/mNcGdfS.png http://i.imgur.com/mNcGdfS.png Precisely, the slope indicates the same thing. Unfortunately the vast majority of a general audience has forgotten what a slope is, so rather than confuse them, I explained it differently. > Musk and Broder 'agree' that the vehicle's actual range was greater than it estimated. Isn't that explained by the reserve power noted in Musk's blog?
doe88 14y ago
That's why it's called an estimation.
- arrrg 14y ago
  Shouldn’t the estimation be conservative, not generous? Especially in this case?
  - deleted 14y ago
    [deleted]
    - lutusp 14y ago
      The reason for this is that the range estimator can't predict things the driver might do to spoil the forecast, like run the heater, or drive faster than the speed the estimator uses for its assumptions, or engage in urban stop-and-go driving -- all of which Broder did. This is not to suggest wrongdoing, only that the assumptions were overly optimistic. > Estimation theory is an established field, and this is the most basic type of problem. All estimations in this class must make assumptions about future behavior. Changes in behavior change the estimate.
      - freyr 14y ago
        Sorry, I didn't realize anybody had responded when I deleted my post. > The reason for this is that the range estimator can't predict things the driver might do to spoil the forecast Notice that all of the lines are extremely linear, meaning that Broder's behavior (or a miscalibration) caused a consistent bias in the estimate -- for 500 miles! It's very possible to design an estimator that can take this into consideration and make more accurate predictions. > All estimations in this class must make assumptions about future behavior. Changes in behavior change the estimate. Obviously. So what assumptions is it making? "My estimate has been consistently off for the last 250 miles, but it's going to be correct in the next 250 miles.... I can just feel it!" > Changes in behavior change the estimate. They should, but apparently they don't in this case.
  - 14y ago
ccarnino 14y ago
While the term estimation is by definition not exact, I challenge anyone to find a car on sale that has 100% accurate estimation. It's just not possible. The point, imho, is that the press is always trying to find a story also where there isn't. Sad for them, this time there's the hard data to support Tesla's facts.
- freyr 14y ago
  Nobody's claiming 100% accurate estimation is the standard. But a consistent 20% error is REALLY bad, if the engineers are trying to design an accurate estimator.
bstar77 14y ago
Back when I owned one of the original Honda Insights, it became very obvious that I would need to adjust my driving habits to fully take advantage of the car's enormous driving range. If I drove like a typical New Jersey-ian then my range would have been somewhere around 450 miles. With some adjustments (namely going around 65mph at most), I could regularly attain 700+ range. This is an adjustment many people absolutely refuse to make. Once I really learned how to get the most out of my car the milage numbers were unbelievable. When I sold the car my lifetime milage was 68 mpg over 130,000 miles (in nj climate). I can see why Musk is so frustrated... he gets a reviewer that has no interest whatsoever in understanding the vehicle's prime operating conditions and instead is driving the car like a Hertz rental. When going on a long range trip, it should be obvious that you need to drive conservatively. Use the car's incredible performance for shorter trips so that you are not at risk. I have no problems with these limitations, and I think they are acceptable. I was quite impressed that the range numbers for Tesla were over 500 miles... my current kia rio can't touch that despite getting nearly 50mpg. I have a feeling the media is never going to "get" electric cars because they don't get conservation.
- Domenic_S 14y ago
  > my current kia rio ... nearly 50mpg I have to ask about this. The highest EPA estimates (which are notoriously generous) for the 2013 Rio are 37 MPG [1]. [1] http://www.fueleconomy.gov/feg/bymodel/2013_Kia_Rio.shtml http://www.fueleconomy.gov/feg/bymodel/2013_Kia_Rio.shtml
  - adrianpike 14y ago
    With a more conservative driving style, it's quite doable to get much better range than those estimates. It's quite fun, actually!
    - InAnEmergency 14y ago
      Agreed. My wife's hybrid is rated at 35mpg, but it regularly gets more than 40mpg, sometimes as much as 48mpg. Of course, if you get really creative... https://secure.drivers.lexus.com/lexusdrivers/magazine/articles/Vehicle-Insider/How-I-Got-85-Mph-in-the-Lexus-HS-250h https://secure.drivers.lexus.com/lexusdrivers/magazine/artic...

17 points by dsberkholz 14y ago

msrpotus 14y ago

Anyone know if that's typical for batteries in cold weather or is Tesla's exceptionally bad?

potatolicious 14y ago
Not all batteries - but lithium batteries in general are known for greatly reduced performance in the cold. Take your camera out in the winter some time and you'll find that it'll drain several times faster than normal. I read a recent interview with a well-known landscape photographer who shoots in the Arctic - he carries a whole bandolier of batteries, kept close to his chest at all times to keep them warm. Apparently in the extreme Arctic cold the batteries are reduced to literally a few dozen shots before dying.

cryptoz 14y ago

This isn't a deeper look. It's a shallower look. Didn't Musk say that the estimated range is dependent on speed, and that Broder sped illegally fast for part of the trip? There are other factors, as well. There may well be something to say about Tesla's estimations being off, but this isn't it.

freyr 14y ago
"Didn't Musk say that the estimated range is dependent on speed" Did he? Because from this figure, it appears the estimated range is NOT dependent on speed (as, of course, it should be). Notice that the lines are extremely linear, with identical slopes throughout. If he sped for part of the trip, why don't we see steeper slopes during those times? So Broder "sped illegally fast." What does this even mean? The speed limit is 55 mph on most highways, but nobody goes at that speed. Can the Tesla range estimator not acknowledge speeds about 55 mpg?
- loeg 14y ago
  > The speed limit is 55 mph on most highways Really? In this part of the country (pacific northwest) the speed limit on interstates is 60 mph in the city and 70 mph in the country.
  - freyr 14y ago
    You're right. It looks like 65-75 is common throughout the country. Guess I haven't looked at a posted speed limit in a while.

rgovostes 14y ago

What the article is explaining can be summarized in this chart: http://i.imgur.com/mNcGdfS.png http://i.imgur.com/mNcGdfS.png But I think this is incorrect: > In nearly every case, the Tesla gets about 20% fewer miles out of each charge than it estimated. Musk and Broder 'agree' that the vehicle's actual range was greater than it estimated. Musk's wrote, > Then he bizarrely states that the screen showed “Est. remaining range: 32 miles” and the car traveled “51 miles," contradicting his own statement... The car actually did an admirable job exceeding its projected range. As an aside, please disable Tynt on your blog.

dsberkholz 14y ago
> What the article is explaining can be summarized in this chart: http://i.imgur.com/mNcGdfS.png http://i.imgur.com/mNcGdfS.png Precisely, the slope indicates the same thing. Unfortunately the vast majority of a general audience has forgotten what a slope is, so rather than confuse them, I explained it differently. > Musk and Broder 'agree' that the vehicle's actual range was greater than it estimated. Isn't that explained by the reserve power noted in Musk's blog?

doe88 14y ago

That's why it's called an estimation.

arrrg 14y ago
Shouldn’t the estimation be conservative, not generous? Especially in this case?
- deleted 14y ago
  [deleted]
  - lutusp 14y ago
    The reason for this is that the range estimator can't predict things the driver might do to spoil the forecast, like run the heater, or drive faster than the speed the estimator uses for its assumptions, or engage in urban stop-and-go driving -- all of which Broder did. This is not to suggest wrongdoing, only that the assumptions were overly optimistic. > Estimation theory is an established field, and this is the most basic type of problem. All estimations in this class must make assumptions about future behavior. Changes in behavior change the estimate.
    - freyr 14y ago
      Sorry, I didn't realize anybody had responded when I deleted my post. > The reason for this is that the range estimator can't predict things the driver might do to spoil the forecast Notice that all of the lines are extremely linear, meaning that Broder's behavior (or a miscalibration) caused a consistent bias in the estimate -- for 500 miles! It's very possible to design an estimator that can take this into consideration and make more accurate predictions. > All estimations in this class must make assumptions about future behavior. Changes in behavior change the estimate. Obviously. So what assumptions is it making? "My estimate has been consistently off for the last 250 miles, but it's going to be correct in the next 250 miles.... I can just feel it!" > Changes in behavior change the estimate. They should, but apparently they don't in this case.
- 14y ago

ccarnino 14y ago

While the term estimation is by definition not exact, I challenge anyone to find a car on sale that has 100% accurate estimation. It's just not possible. The point, imho, is that the press is always trying to find a story also where there isn't. Sad for them, this time there's the hard data to support Tesla's facts.

freyr 14y ago
Nobody's claiming 100% accurate estimation is the standard. But a consistent 20% error is REALLY bad, if the engineers are trying to design an accurate estimator.

bstar77 14y ago

Back when I owned one of the original Honda Insights, it became very obvious that I would need to adjust my driving habits to fully take advantage of the car's enormous driving range. If I drove like a typical New Jersey-ian then my range would have been somewhere around 450 miles. With some adjustments (namely going around 65mph at most), I could regularly attain 700+ range. This is an adjustment many people absolutely refuse to make. Once I really learned how to get the most out of my car the milage numbers were unbelievable. When I sold the car my lifetime milage was 68 mpg over 130,000 miles (in nj climate). I can see why Musk is so frustrated... he gets a reviewer that has no interest whatsoever in understanding the vehicle's prime operating conditions and instead is driving the car like a Hertz rental. When going on a long range trip, it should be obvious that you need to drive conservatively. Use the car's incredible performance for shorter trips so that you are not at risk. I have no problems with these limitations, and I think they are acceptable. I was quite impressed that the range numbers for Tesla were over 500 miles... my current kia rio can't touch that despite getting nearly 50mpg. I have a feeling the media is never going to "get" electric cars because they don't get conservation.

Domenic_S 14y ago
> my current kia rio ... nearly 50mpg I have to ask about this. The highest EPA estimates (which are notoriously generous) for the 2013 Rio are 37 MPG [1]. [1] http://www.fueleconomy.gov/feg/bymodel/2013_Kia_Rio.shtml http://www.fueleconomy.gov/feg/bymodel/2013_Kia_Rio.shtml
- adrianpike 14y ago
  With a more conservative driving style, it's quite doable to get much better range than those estimates. It's quite fun, actually!
  - InAnEmergency 14y ago
    Agreed. My wife's hybrid is rated at 35mpg, but it regularly gets more than 40mpg, sometimes as much as 48mpg. Of course, if you get really creative... https://secure.drivers.lexus.com/lexusdrivers/magazine/articles/Vehicle-Insider/How-I-Got-85-Mph-in-the-Lexus-HS-250h https://secure.drivers.lexus.com/lexusdrivers/magazine/artic...