6 ms·

He has a new article from February 12 http://wheels.blogs.nytimes.com/2013/02/12/the-charges-are-flying-over-a-test-of-teslas-charging-network/?ref=johnmbroder

by VMG 14y ago

He has a new article from February 12 http://wheels.blogs.nytimes.com/2013/02/12/the-charges-are-flying-over-a-test-of-teslas-charging-network/?ref=johnmbroder http://wheels.blogs.nytimes.com/2013/02/12/the-charges-are-f... More strange things are claimed At that point, I was already experiencing anxiety about range and had called a Tesla employee from the New Jersey Turnpike to ask how to stretch the battery. She said to shut off the cruise control to take advantage of battery regeneration from occasional braking and slowing down. Based on that advice, I was under the impression that stop-and-go driving at low speeds in the city would help, not hurt, my mileage. What?

stcredzero 14y ago
> Based on that advice, I was under the impression that stop-and-go driving at low speeds in the city would help, not hurt, my mileage. If I were hiring John Broder to be a journalist covering electric cars, that right there would be enough to reveal him as disqualified: Doesn't know even the basics of thermodynamics or can't apply it to his subject.
- VMG 14y ago
  On the other hand, the supposed advice from the employee doesn't sound right either, if that is what she actually said.
  - stcredzero 14y ago
    Irrelevant. He doesn't say that's what she said. He says that's how he interpreted it.
  - nicholassmith 14y ago
    Without knowing the exact conversation it doesn't sound super off, regenerative braking technology has been used in F1 for a while to power the KERS system, but stop-start traffic is completely different to the occasional slow down on a motorway.
- dbuxton 14y ago
  I don't know, consumers are told lots of wacky counter-intuitive things about "how to eke performance out of technology in practice". Think of the way that lots of people like to repeatedly run their laptop batteries down because they think that it helps preserve battery life, even though that hasn't been true for about a decade. However I think that your comment about thermodynamics is revealing because it seems to me that the real point of this article is that driving an electric car requires consumers to learn a lot (about entropy!) and think very differently from driving a normal car. It sounds frankly stressful to drive, even if everything works perfectly. That's where I think the real damage is.
  - stcredzero 14y ago
    My solution would be to only use half the stated range. It would be perfect for me, even so.
  - gus_massa 14y ago
    You don't need a Thermodynamics Ph.D. to understand this. Moreover the normal (gas) cars have the same behavior. So it's annoying that a car expert don't know it. You get the best mpg at a constant speed of ~50mph, and it's better with the cruise control because it reduce the times that you need to accelerate or decelerate. If you go too fast, the mpg drops because you need more fuel to compensate the additional resistance. If you accelerate and brake (for example in a city), the mpg drops because you need more fuel to accelerate and when you brake the energy goes away as heat. The advantage of the regenerations brakes is that some of the energy that is "lost" as heat braking is stored and used again to accelerate. This is not magic. It doesn't make braking lossless, it only recycles part of the energy so accelerating and braking is not so bad (it's only bad). This is well known for the electric and hybrid cars (I think that there are some tries to do something like this for gas cars, perhaps store the energy mechanically, I'm not sure.) I think that the recommendation was (paraphrase) "If you are going to drive inside a city, it's better to turn off the cruise control." The articles that he understood something like (paraphrase) "It's better to drive inside a city than in a highway with cruise control." It's very surprising that a car expert can understood this so totally wrong that it look like it was a willfully misunderstandment.
- btilly 14y ago
  Doesn't know even the basics of thermodynamics or can't apply it to his subject. Oh really? You probably also think that cold water freezes faster than hot. Taking the thimbleful of knowledge that you have and making snap judgements based on it will often mislead you. In the case of the cars, without looking it up it is not obvious to me which is worse - the energy loss in starting and stopping at low speeds, or the quadratically scaling energy loss from wind resistance at high speeds. Certainly if you go fast enough you'll find that your driving range drops substantially - this is why the old 55 mph limit was passed during the oil crisis. If I am not certain without looking it up, then I can't fault someone else for not knowing it either. About the water, if you have equal amounts of hot and cold water in wooden buckets and put them out in the snow, the hot water can easily freeze faster. Several possible factors are known, but their relative importance is unclear. See http://math.ucr.edu/home/baez/physics/General/hot_water.html http://math.ucr.edu/home/baez/physics/General/hot_water.html for a detailed discussion.
  - stcredzero 14y ago
    > In the case of the cars, without looking it up it is not obvious to me which is worse I wouldn't hire you either. > About the water Your example digs your hole deeper. There's a fundamental difference between applying thermodynamics in this case, and the regenerative braking one. That you don't know that is what's damning.
    - TillE 14y ago
      I guess the point was: because some nonintuitive things can happen, conservation of energy isn't real. Or something.
      - makomk 14y ago
        Funnily enough, going further in stop-and-go urban traffic than on the highway doesn't violate the conservation of energy either. (Also, remember you can't just go arbitrarily slowly on the highway - that's unsafe and a lot of places ticket people for it.)
    - 14y ago
baggachipz 14y ago
Broder seems stunned to learn that he is not, in fact, driving a perpetual motion machine.

by VMG 14y ago

stcredzero 14y ago

> Based on that advice, I was under the impression that stop-and-go driving at low speeds in the city would help, not hurt, my mileage. If I were hiring John Broder to be a journalist covering electric cars, that right there would be enough to reveal him as disqualified: Doesn't know even the basics of thermodynamics or can't apply it to his subject.

VMG 14y ago
On the other hand, the supposed advice from the employee doesn't sound right either, if that is what she actually said.
- stcredzero 14y ago
  Irrelevant. He doesn't say that's what she said. He says that's how he interpreted it.
- nicholassmith 14y ago
  Without knowing the exact conversation it doesn't sound super off, regenerative braking technology has been used in F1 for a while to power the KERS system, but stop-start traffic is completely different to the occasional slow down on a motorway.
dbuxton 14y ago
I don't know, consumers are told lots of wacky counter-intuitive things about "how to eke performance out of technology in practice". Think of the way that lots of people like to repeatedly run their laptop batteries down because they think that it helps preserve battery life, even though that hasn't been true for about a decade. However I think that your comment about thermodynamics is revealing because it seems to me that the real point of this article is that driving an electric car requires consumers to learn a lot (about entropy!) and think very differently from driving a normal car. It sounds frankly stressful to drive, even if everything works perfectly. That's where I think the real damage is.
- stcredzero 14y ago
  My solution would be to only use half the stated range. It would be perfect for me, even so.
- gus_massa 14y ago
  You don't need a Thermodynamics Ph.D. to understand this. Moreover the normal (gas) cars have the same behavior. So it's annoying that a car expert don't know it. You get the best mpg at a constant speed of ~50mph, and it's better with the cruise control because it reduce the times that you need to accelerate or decelerate. If you go too fast, the mpg drops because you need more fuel to compensate the additional resistance. If you accelerate and brake (for example in a city), the mpg drops because you need more fuel to accelerate and when you brake the energy goes away as heat. The advantage of the regenerations brakes is that some of the energy that is "lost" as heat braking is stored and used again to accelerate. This is not magic. It doesn't make braking lossless, it only recycles part of the energy so accelerating and braking is not so bad (it's only bad). This is well known for the electric and hybrid cars (I think that there are some tries to do something like this for gas cars, perhaps store the energy mechanically, I'm not sure.) I think that the recommendation was (paraphrase) "If you are going to drive inside a city, it's better to turn off the cruise control." The articles that he understood something like (paraphrase) "It's better to drive inside a city than in a highway with cruise control." It's very surprising that a car expert can understood this so totally wrong that it look like it was a willfully misunderstandment.
btilly 14y ago
Doesn't know even the basics of thermodynamics or can't apply it to his subject. Oh really? You probably also think that cold water freezes faster than hot. Taking the thimbleful of knowledge that you have and making snap judgements based on it will often mislead you. In the case of the cars, without looking it up it is not obvious to me which is worse - the energy loss in starting and stopping at low speeds, or the quadratically scaling energy loss from wind resistance at high speeds. Certainly if you go fast enough you'll find that your driving range drops substantially - this is why the old 55 mph limit was passed during the oil crisis. If I am not certain without looking it up, then I can't fault someone else for not knowing it either. About the water, if you have equal amounts of hot and cold water in wooden buckets and put them out in the snow, the hot water can easily freeze faster. Several possible factors are known, but their relative importance is unclear. See http://math.ucr.edu/home/baez/physics/General/hot_water.html http://math.ucr.edu/home/baez/physics/General/hot_water.html for a detailed discussion.
- stcredzero 14y ago
  > In the case of the cars, without looking it up it is not obvious to me which is worse I wouldn't hire you either. > About the water Your example digs your hole deeper. There's a fundamental difference between applying thermodynamics in this case, and the regenerative braking one. That you don't know that is what's damning.
  - TillE 14y ago
    I guess the point was: because some nonintuitive things can happen, conservation of energy isn't real. Or something.
    - makomk 14y ago
      Funnily enough, going further in stop-and-go urban traffic than on the highway doesn't violate the conservation of energy either. (Also, remember you can't just go arbitrarily slowly on the highway - that's unsafe and a lot of places ticket people for it.)
  - 14y ago

baggachipz 14y ago

Broder seems stunned to learn that he is not, in fact, driving a perpetual motion machine.