Winter chills limit range of the Tesla Model S electric car
news.consumerreports.org
news.consumerreports.org
I recall one very long-winded rant here on HN where a commenter described Broder as having an axe to grind, a shyster, and concluded his comment with "Fuck the NYT. Fuck Broder."
All of this, in the grand scheme of the automotive industry, are small ripples. Tesla will survive this, and electric sales will proceed more or less unimpeded.
The real takeaway here is keeping your cool and turning off the "mob outrage" circuit in your brain. The drummed up pitchfork-wielding mob was, in the end, a more sobering spectacle than any electric car issue.
I must sound like a broken record by now. It seems every month some one-sided account will splash onto HN's front page, stir up a hornet's nest of indignation, resulting in long, angry rants and calls for heads to roll. Inevitably a more balanced picture emerges - but the usual suspects will be back the next time someone writes a blog post manipulating their outrage.
Whenever a blog post is so utterly absurd and ridiculous that it demands unfettered and unrestrained anger, there is a strong chance you're being played.
(lest you doubt this, go dig up some of the Boeing 787 threads and see what people were saying about him there -- the level of outright worship of him in the HN comments was more than a little bit scary)
I'm getting a tub of popcorn so I can be adequately prepared for his next crusade. I'm sure that this time it will paint him in a positive light...
So while I wouldn't call it a perfect review, the points it made were relevant. You can't expect people to change cabin temperature settings to be uncomfortable, drive 45mph on the freeway, not drive when it's cold out, and to know the nuances of the car's range estimator. (If the range display says "0 miles", it's reasonable to assume that the battery is dead.)
Remember: the car mostly worked fine, which is a huge coup for electric cars. The article emphasizes the negatives, but the negatives are all things that can be fixed -- many with a simple software upgrade. So on that note, I don't think the review was particularly bad, and I certainly don't think the Times was compensated to make the car look bad, as Musk accuses.
(The article is also a good human factors and UI case study. When customer service and an electronic read-out disagree, one implicitly trusts the read-out more. It happens to airline pilots, too.)
Sure he can.
Rather than an error of memory, I think it's far, far more likely he just made them up to create an illusion of accuracy that he simply did not do the work to record.
And it's impossible to tell either way. So clearly the over the top attitude of Musk was unwarranted.
You're prepared to take Musk's interpretation of his logs (which we know were wrong about whether the car would move or not - the flat bed operator corroborates Broder) over Broders notes.
I'm familiar enough with logs telling you things different to what you expected to not think it's all that cut and dried. In fact, our QAs use stop watches and keep notes, and we trust those over what the software thinks is happening for certain kinds of issues.
No real-world fault of the Tesla justifies a reporter trying to bend the facts or going out of the way to manufacture a story. Broder clearly set out to drain the Tesla and get it on a tow truck, and he tried his damnedest to make that happen.
That is a heavy charge and the evidence just doesn't support throwing it around so haphazardly. Musk's jumping to that conclusion did this entire discussion a disservice.
Remember, Musk stated as fact that Broder "drove around in circles" for 0.6 miles trying to run the batteries out. His casual accusation on just that point alone makes it hard to take the rest of his analysis (of his company-provided data) without a grain of salt.
I'm posting these without commentary:
Broder: While Mr. Musk has accused me of doing this to drain the battery, I was in fact driving around the Milford service plaza on Interstate 95, in the dark, trying to find the unlighted and poorly marked Tesla Supercharger.
That someone found the charger faster than him is neither here nor there (it's irrelevant to the review he wrote). His story stands, and Musk's accusations look increasingly like complete libel.
Again, accusing a journalist of maliciously fabricating anything is a huge deal. It is not something that is taken lightly, and if there's is an inkling of truth to it the folks at the NYT will deal with it and we will know about it.
Well good, I posted them without commentary for that reason specifically. The goal was to allow you to guide your own thinking.
The video makes it seem as if the charger is easy to find, but only if you know where it is already. I can't see how anyone who has never visited that station before would be able to make the same bee-line for the charger without circling the parking lot at least once.
Imagine getting up in the morning, you check your phone, 25% ohh well i am not going to talk a lot to day so says my crystal ball. How many would do that? The NY journalist did his first drive in the Tesla S, and decided to base his drive on his experience, which was zero. Normal people, and other reviewers knew better, better charge to the max when i am actually testing the limits of the car. Not the limits of the reviewers knowledge.
If he had done as he should he would still have been able to write all the negative parts, the drop over night the limits because of the cold etc. it might have been a worthwhile article, like this one.
Journalism is not science.
The outrage seemed normal: Broder and Consumer Reports seem to think that leaving the car unplugged overnight is normal or should ever be done. Or they combine 2 days+1 overnight unplugged, and call that a day, knowing that the cold overnight storage sapped the battery.
So either they are acting stupid, or don't really know how to test battery-powered vehicles. Sure, you don't have to follow instructions, but if you don't, you will have problems, no matter what excuse you have about 'testing something'.
If Broder can't remember what happened, farting around for details, he should have been a professional and videotaped at intervals so he could check the facts.
It's a big deal when it labels someone as a liar and a fraudster. It's a big deal when tens of thousands of knee-jerk readers are calling for someone's immediate firing. It's a big deal when someone's entire career is threatened by a bunch of people "not taking things seriously" on the internet.
Not taking things seriously is the problem. People in internet-mob-outrage-mode are flippant, quick to judge, and unreasoned, believing that just because it's a bunch of electrons that there are no consequences.
Hell, this situation in specific is lighter than it could be. On Reddit we've seen in the past vigilantes who turned internet-angry-comments into real-life threats against lives, we've even seen one case where someone committed suicide after being hounded by thousands of "random internet comments" that are (according to you) "no big deal" - the accusation was molestation, btw.
Accusations of fraud are Serious Business(tm) for a journalist - there are real consequences for real people when that is tossed around. Just because you don't take your own words seriously doesn't mean other people don't.
Yours is the worst kind of defense - akin to a bully saying "gosh, I was just horsin' around" when called on the awful things that have been coming out of his mouth.
In addition, the Tesla can lose range even when not parked overnight; it can simply be driven when it is very cold outside.
You can "instruct" people not to do these things, just like Steve Jobs "instructed" people not to hold their iPhones "like that", but you will be ignored.
> Anyhow, after a seven-hour overnight park (unplugged) and temperatures dropping below freezing, the "rated" range dropped to 65 miles. (Because we're tracking energy poured into the Tesla at our track, I resisted the temptation to top off at home, like a typical owner would.)
That reads to me like CR says that charging at night is the expected normal.
Basically, everybody assumes that they are correct and that all fair rational people would draw the same conclusions as them given the same information.
When that doesn't happen, it can't be because the person is wrong; their interlocutor must be wrong. If the interlocutor continues to deny that they're wrong, they must be intellectually or morally defective.
That's what's happening here: people are assuming that since Broder doesn't agree with them, he must be deliberately deceitful. You can search any Tesla thread on the net and find the word "liar" or "lies".
Personally I think that Broder made some factual errors but that the big picture -- the battery ran flat in spite of the advice given -- is what matters. Maybe there's an RTFM problem here, maybe there isn't. I don't really care at this point because I happen to know that all new technologies ever have had embarrassing teething problems. When Musk's rockets blow up nobody seems to blame the journalists.
Musk overreacted because it's his baby and because surely anyone who disagrees with the wonderfulness of Tesla must, by the reasoning of Naïve Realism, be intellectually and morally defective.
Sprinkle in the way that humans love to form themselves into tribes, the "hostile media effect" and attitude polarisation and basically we're just hearing the same tunes that are hummed about Microsoft / Google / Obama / Bush / Rails / node.js / whatever.
[0] http://en.wikipedia.org/wiki/Na%C3%AFve_realism_(psychology)
Thank you for keeping HN great. I am in your debt.
ohstopityou.jpg
That's a pretty nasty meme and it seems to be spreading. No, people: regenerative braking mitigates the effects of braking on fuel efficiency! It doesn't overcome or reverse them. The laws of physics say that driving on the freeway with no braking is, and will always be, much better for fuel efficiency, in any conceivable vehicle.
It's a fixed gear, so this is actually plausible.
On an automatic transmission the transmission control module will figure out the gear for you at given conditions (won't let you get too low in the same gear) and what you say will be true.
http://www.fueleconomy.gov/Feg/bymodel/2012_Toyota_Prius.sht...
Aerodynamically, the slower you drive, the more efficient you drive. The exact curve will depend on air pressure, amount of moisture in the air, etc.
For the engine, it is more complicated. You will want to keep its temperature and rpm at ideal levels. rpm and the gearing in the drive train determine what speed(s) that corresponds to (I guess drive train losses will depend a bit on the gearing, too, but that effect should be minimal)
For the two combined, this gets really complicated. Do you drive at the engine-optimal 45 or does the gain due to lower speed offset the loss in engine efficiency at 44? If 44 is more efficient now, will it stay that when it starts to rain? When you enter a different road surface? When your tires heat up and tire pressure increases slightly? When you have a window open?
http://en.wikipedia.org/wiki/Fuel_economy_in_automobiles#Spe... shows how convoluted this can get.
http://www.teslamotors.com/goelectric/efficiency
(the graph)
Efficiency, in terms on miles/gallon, is always a trade-off between traveling fast enough that the overhead of running the vehicle is less significant but slow enough that wind resistance doesn't dominate. There's a sweet spot in there.
http://www.teslamotors.com/blog/model-s-efficiency-and-range
The car expends energy just sitting at zero MPH -- the computer and lights, air conditioning and heating, things like that. So the graph is correct -- there is an energy expenditure to "go" zero miles per hour.
> I was hoping the units were [Watts][hours]/[minutes] or something to make everything better.
When the speed is zero, it stops mattering which units it's expressed in. :)
Personally, I'd wager they followed the old scientific adage: "If you wish your function to be linear, sample two and only two points".
1. Not energy/distance, but energy/speed.
2. Notwithstanding the cart's labeling ("Wh/mi"), its values aren't predicated on a division of energy by speed. "Wh/mi" doesn't literally mean mean "watt-hours divided by miles per hour", it means "the relationship between watt-hours and vehicle miles per hour".
> Personally, I'd wager they followed the old scientific adage: "If you wish your function to be linear, sample two and only two points".
Yes, except the chart isn't linear. Just for fun, here's a polynomial function that matches the chart's results reasonably well:
f(x) = 0.03165008148658699 * x^2
+ 0.2559872636164877 * x
+ 106.19966024840329
http://i.imgur.com/rLmaN90.png
So ... no division by zero. BTW I worked this up with the help of Sage, my current favorite, free math tool:
There is an actual head smacking quote in the article where he says he took a country road instead of the highway in hopes of getting more range by taking advantage of regenerative braking... How can an EV car reviewer for Consumer Reports be so ignorant?
This is two articles now where the authors, or technicians they're talking to, seem to think the model S has found away around the laws of thermodynamics. It has not. Regenerative breaking will not charge your battery any more than you drained it getting up to that speed in the first place. In fact, by definition, it will charge the battery less. So anyone who thinks the key to getting more range out of an electric vehicle is to abandon smooth and steady driving and find a way to slam on the brakes is in for a rude surprise.
The regen braking isn't the sole source of efficiency gain -- aerodynamic drag, gearing and engine optimizing are responsible for the "true" gains -- but regen braking makes it more possible to realize the "true" gains because you're no longer throwing away all of the true gains on braking.
The above statement is false. Regenerative braking in the Tesla (which only has regenerative braking on the rear wheels) only recovers about 20% of the energy lost in stopping the car. Accelerating again requires 100% of the car's final kinetic energy to be provided by the battery. Therefore city driving is always less efficient than driving at a steady speed unless you're planning to drive at 90 miles per hour.
All regenerative braking can do is minimize the losses caused by stop-and-go driving, it is never an improvement over driving at a steady speed at the same average speed or, for that matter, most higher speeds.
I wish this myth would go away -- by way of some physics education.
> ... you're no longer throwing away all of the true gains on braking.
No, only 80% of them. Which means you would have to drive very fast to equal the losses of stop-and-go driving.
According to this, the tesla regenerative braking is just as efficient as the motor is at acceleration. Result: up to 64% of the original battery energy returned to the battery.
http://www.teslamotors.com/blog/magic-tesla-roadster-regener...
And this page about the Volt suggests that the efficiency might get up to 70% in some situations.
http://www.designnews.com/document.asp?doc_id=235313&dfp...
This is confirmed by measurements which show pretty much all hybrid vehicles get better mileage in city driving than in highway driving.
That's true but misleading. If the motor's combined electrical and mechanical losses cause only 64% of the battery's energy to propel the car forward, then by that reasoning, only 64% of the braking energy is made available for charging.
Let's look at all the factors that influence the outcome:
1. Both electrical and mechanical losses must be accounted for.
2. The electrical loss creates a factor of 0.8, the mechanical loss also create a factor of 0.8. Result 0.64.
3. On the Tesla, only the rear wheels have regenerative braking, the front wheels have disc brakes. Factor 0.5, so we are now at 0.32.
4. During a stop, the car pitches forward onto the front wheels and unloads the rear wheels, this needs to be taken into account. Factor 0.8 for a total of 0.2: 26%.
So I stand corrected -- this analysis concludes that the regenerative braking scheme recovers 26%, not 20%, of the original kinetic energy.
A literature search reveals that the best regenerative braking systems that involve all four wheels and in which every effort is made to maximize efficiency, can produce about a 40% energy recovery:
http://www2.hesston.edu/physics/201112/regenerativeenergy_cw...
A quote: "Since regenerative brakes can only recover about 40% of the energy we take the recoverable energy and multiply by .4 (Everett, Michael)."
The linked paper goes on to show that 40% is actually overly optimistic for various practical reasons. But notwithstanding that, we can take the original 40% figure and apply it to the Tesla. By taking into account that only two of four of the Tesla's wheels have regenerative braking, we arrive at a figure of 20%.
> And this page about the Volt suggests that the efficiency might get up to 70% in some situations.
No reputable source makes claims this high for a full round trip from battery stored energy to battery stored energy (the linked article doesn't try to do this). Also, the linked chart reports energy recovered in a four-wheel test and measured before being applied to the battery, not energy delivered to the battery as stored energy.
> This is confirmed by measurements which show pretty much all hybrid vehicles get better mileage in city driving than in highway driving.
That's true, but that doesn't result from regenerative braking. It results from lower average speeds and reduced wind and mechanical resistance.
Remember that regenerative braking cannot possibly improve on driving at a steady speed. That would violate some very basic physical principles.
I would hope that the on board software wouldn't use those front brakes during light deceleration. Anybody know more about this?
No, this isn't safe. A car that only allowed one set of wheels to brake would in some cases spin around dangerously. Safe brakes must apply the same force on all four (or more) wheels simultaneously.
Remember that the computer can't possibly know if the car is sliding across black ice, a situation in which the application of even force is an absolute requirement for a safe stop.
You're arguing against something I was careful not to say.
That may be true, but it's not the topic. The topic is how efficient regenerative braking is on the Tesla Model S.
I suspect that in both the NYT article and in this CR article, the author is mistaken about the role of regenerative braking on fuel efficiency, but they are not incorrect to point to regenerative braking as the enabler of improved fuel efficiency.
Some made up numbers to illustrate the point. I do not know if these apply to the Model S specifically but do apply to other vehicles with regen braking, familiarity with which is likely to have influenced the authors' explanations.
City driving vs. highway driving:
Lower drag: +20% efficiency
Lower engine RPM: +20% efficiency
More stop and go with normal braking: -50% efficiency
More stop and go with regen braking: -50%(.6) = -30% efficiency
= Net city driving with normal braking: -10% efficiency
= Net city driving with regen braking: +10% efficiency
But regenerative braking cannot produce net positive energy compared to not braking at all -- that violates basic physical principles.
Regenerative braking is better than no regenerative braking, but regenerative braking is not better than not braking at all. That has been the point all along.
> = Net city driving with regen braking: +10% efficiency
No, not compared to driving at a steady pace. If the scenario you describe were so, it would represent a gain in energy greater than 100%, and that is not possible.
Stop-and-go driving is always less efficient than driving at a steady pace at the same average speed. Regenerative braking can only minimize the loss caused by stop-and-go driving, it can't reverse it -- it can't produce a net gain as you are implying.
> More stop and go with normal braking: -50% efficiency
Wrong value. Apart from the fact that the number is invented, because each stop turns all the car's kinetic energy into heat, the number should be -100%. Either that or perform a full analysis, with a listing of all the factors.
After you recover 20% of the energy with regenerative braking, you end up with -80% instead of -100%.
I ride a low-power motorcycle. On the freeway, I get about 50 mpg. On back roads, with braking and generally higher rpm, I get 60+ mpg. For my low-power bike, the drag at freeway speeds takes more effort to overcome than does the varying speed and braking of back road riding.
And that is without regenerative braking. If I had regen braking, I'd get even better economy on back roads.
Not sure how Tesla does that (if it does 'engine braking')
And of course that's negated by the fact that you'll be going uphill in the way back, using more energy
Tesla uses the electric motors that normally propel the car by expending battery energy, but "in reverse" to generate a small amount of power while decelerating. It's better than nothing, but it's not as efficient as many people seem to believe.
> And of course that's negated by the fact that you'll be going uphill in the way back, using more energy
Good example -- going downhill with your foot on the brake, recovers 20% of the car's kinetic energy lost by descending the hill. Going uphill again requires 100%$ of the required energy from the battery. So it's a net loss of 80% of the total energy represented by climbing and then descending the hill.
How does that help anyone, including Tesla?
Where is this stupid idea coming from? It's absolutely false -- regenerative braking can only reduce losses caused by braking, it doesn't extend the range of the car compared to driving at a steady speed. Don't expect to gain anything by choosing stop-and-go driving over steady-speed driving -- it doesn't work that way.
According to technical estimates, regenerative braking only recovers 20% of the energy otherwise lost in reducing the car's speed, but gaining that speed back requires ... wait for it -- 100% of the car's kinetic energy from the battery. Regenerative braking is better than turning all the car's kinetic energy into heat, but it has no advantage over maintaining a steady speed.
I wish this myth would go away, preferably by some education in physics.
Of course, the energy consumed in 1h of cruise driving is less than 1h of stop/go "at the same speeds" (YMMV of course)
My comment wasn't about low speeds, it was about stop-and-go driving. Driving at a steady speed is much more efficient than braking and then accelerating again.
This is journalism.
Broder's sloppy crap was not.
Note the real issue, not that Mr. NYT's exaggerations and lies were 'close enough.'
This was never about defending Mr. Hyperbole, AKA Mr. Musk.
It was about a NYT reporter feeling free to take license because it encapsulated the spirit of the truth or some other lukewarm embrace of poor reporting.
Alright, what am I missing? People Who Should Know keep making this strange claim that you get more energy from regenerative braking than not braking at all. I don't understand - when you're braking, you're only reclaiming energy you put there by accelerating in the first place.
I would have thought that freeway driving would be fairly ideal, since you're at a steady speed and basically only need to overcome air and rolling resistance, whereas if you're regularly using braking, you're also having to reaccelerate, plus you're losing energy in the form of heat and possibly sound.
I get the idea that adding regenerative brakes in the first place will increase your range, but I don't see why your range would be shorter because you don't get to brake. Am I missing something somewhere, or am I expecting too high a knowledge of physics in my car reviewers?
In fact, even in less respectable newspapers this is generally true. I worked at a less respectable newspaper for several years; whenever I wandered into the editorial area I was treated as being slightly below toenail clippings in the order of creation.
It's best to think of a newspaper as a device that multiplexes two totally independent feeds. One feed is ads and classifieds, the other is editorial material.
Conspiracy theories to the contrary are just embarrassing. Really. Journalists are tremendously and fiercely proud of themselves (to a fault). Suggesting to a journalist at a serious newspaper that their writing is biased based on what the display department did last week is going to get a mix of reactions from laughter to a punch on the nose for uttering such inflammatory fighting words.
He explains this as his reasoning for not recharging his car... Regardless of if it's cold outside, or if the car is powered by electricity, gas, or good intentions, if the car is telling you that you're running dangerously low on fuel, why would you not stop and refuel? I feel like stopping and refueling would be the real-world scenario.
As I understand it, CR were tracking exactly how much they charged the Tesla at their office (in w, I guess). And he didn't want to mess with that. He also wanted to test the "projected range".
usage of "regenerative braking" makes me doubt his tech credentials, not braking is always more efficient than braking and storing that energy back into the battery.
I strongly feel this is a proxy article to give a saving grace to New York Times bungled review.
follow the https://twitter.com/TeslaRoadTrip to see how different owners are driving their Tesla to prove New York times lied
That said, if we ever want EVs to "take over" the gas-powered engine industry, there's a lot of work to do, and we're a far, far, far cry from running long-range trucks on EV (granted, no one's talking about that now, but that's the obvious ultimate conclusion).
Along these same lines, diesel cars aren't popular in America even though they get better mileage with less-refined fuel. I'm confident that if US auto mfgs wanted to, they could throw enough money at changing the perception of diesel as "dirty" in America to really help diesel take off. Why are we ignoring this perfectly viable, proven, reliable, and ancient technology in favor of battery packs which create tons of hazardous waste to produce and dispose of?!
One reason this hasn't happened is that the goal is a fuel- and energy-efficient car, and turbines aren't very fuel efficient compared to piston engines, a popular misconception to the contrary.
And diesel IS dirty. It's really hard to make one that meets emission standards.
And that is the main reason it's not used more often in the US: It's basically impossible to make it clean enough.
[1]http://www.carmagazine.co.uk/Drives/Search-Results/First-dri...
Why do people actually think braking more would conserve energy?! I remember this being referenced in the NYT article as well...
Is there now a pervasive urban myth amongst electric car owners that you can get free energy from the brakes? Or that you can extend the range in stop and go driving? The NYT journalist did the same thing. That's just crazy.
"I considered stopping in Milford, CT, for a quick "supercharge" as I had a few days earlier, but changed my mind in the spirit of my experiment. I knew the distance to my office was 55 miles at that point, so I decided to risk taking one for the team to determine the Model S real-world range when it's cold outside and you drive the car as you would any other car, electric or not. Call me a gambler, but I kept cruising and crossed my fingers."
He intentionally didn't refuel when he had the chance, but believes this is the same as how he drives a non-electric car. That's insane. But he's so used to the gasoline paradigm (where you can currently refuel in many more places) that he doesn't even realise how crazy he is.
As I said, it's not much different from the person reviewing Linux who (in a Windows mindset) goes looking for downloads of LibreOffice on their website and ends up trying and failing to compile it from source or some other crazy thing that no actual Linux user would do.
Broder: "the temperature was still in the 30s"
Consumer Reports: "45° F"
They drove the car on the cold on purpose instead of waiting for summer to come.
Tesla has data showing that consumer reports was lying, the temperature wasn't 45 degrees but 44 at least for a three minute period. Would you trust a liar?
</end musk defender at any cost bot> Hacker News is now Elon Musk News.