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That Tesla Data: What It Says and What It Doesn’t

wheels.blogs.nytimes.com

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Re: That Tesla Data: What It Says and What It Doesn’t

#21

Post by Lewisham »

jacquesm wrote: post #3

Two bits are completely non-sensical to me, is there any battery technician or otherwise knowledgeable person that can indicate in what conditions this makes any sense? > Beginning early in the morning of my second day with the car, after the projected range had dropped precipitously while parked overnight, I spoke numerous times with Christina Ra, Tesla’s spokeswoman at the time, and Ted Merendino, a Tesla product p…

> That does not make any sense either. Any kind of consumption will ultimately reduce the available range, you don't restore by removing joules from a pack.

I think what is happening is that he thinks the battery actually does have the charge, but the estimate is incorrect because of the cold. What he thinks is going to happen by driving is that the battery will heat up and become more efficient, and the estimated range will raise.

I do not find this an unreasonable mental model, even if it does or does not represent the actual workings of a battery-powered vehicle.

Re: That Tesla Data: What It Says and What It Doesn’t

#22

Post by bitcartel »

luigi wrote: post #7

Overall I think Broder acquits himself well, and his explanation about circling the Milford parking lot makes sense. Also, the Tesla engineer he was on the phone with at the time should have been able to tell Musk that happened (or Tesla should have just asked Broder to comment before posting the rebuttal). His action here is still hard to understand: > The Tesla personnel whom I consulted over the phone – Ms. Ra and…

Given the ambiguity of what the dash was reporting and what Tesla personnel were telling him, it looks like he put his trust in the humans. In that situation, where you've been led to believe the dash behaves like a wonky gauge, it's quite reasonable to not call back.

Re: That Tesla Data: What It Says and What It Doesn’t

#23

Post by jacquesm »

surrealize wrote: post #9
jacquesm wrote: post #3

Two bits are completely non-sensical to me, is there any battery technician or otherwise knowledgeable person that can indicate in what conditions this makes any sense? > Beginning early in the morning of my second day with the car, after the projected range had dropped precipitously while parked overnight, I spoke numerous times with Christina Ra, Tesla’s spokeswoman at the time, and Ted Merendino, a Tesla product p…

Looking at the plots from Musk's blog post, the battery state of charge diminishes a bit overnight, but the estimated range diminishes much more. Presumably because a cold battery has a shorter range. As the battery warms up, the estimated range should go up as well. How much the range goes up probably depends on how much the battery warms up; in the cold morning weather in Norwich, the battery may have warmed up les…

I drove a honda civic hybrid in Northern Ontario for two winter seasons. The batteries where NiMh and the cold was absolutely brutal on them. Indeed they'd recover a bit of charge when warmed up but it was usually very hard to tell if that was because of the engine running or because the batteries warmed up. (and sometimes even harder to tell because the displays wouldn't work at all below -25 celsius).

Maybe the batteries Tesla uses recover better/faster but since it's all electric there is obviously no way to get more power into the pack so the only thing that using a heater will do is drain it, and it will drain it pdq. If I was driving an all electric car and I was worried about my range the one thing you can be sure of is that I would maintain as constant a speed as possible and the heat would be off. After all it is a lot better to arrive at your destination cold than it is to deplete you battery and spending even more time in the cold.

I'm pretty sure Tesla knows the exact power curves for their batteries at any temperature condition that could realistically speaking occur, if they were asleep at the switch that's a big bad problem for them but if they had this info and used it and this is turning into a game of words rather than a game of data then the only thing they should do at this stage is to have a Tesla engineer duplicate the trip conditions to see what the result would be if you behaved rationally rather than irrationally.

That way we'd get some usable information. Experiments are only valid when you can repeat them.

Re: That Tesla Data: What It Says and What It Doesn’t

#25

Post by slantyyz »

dinkumthinkum wrote: post #10

I'm over this he said she said with NYT vs Elon Musk. I love the concept of the Tesla, let's just put up or shut up. Who cares about the times, let's get a new, in depth, independent study. But let's get past this soap opera.

In my mind, the whole thing that turned this into a soap opera was Musk's knee jerk responses on Twitter.

Had he come back with a more measured response (like OXO did with Quirky) and just politely pointed out the inaccuracies of the article and made his same offer of "We'll provide a car to any journalist to do the same test and see what happens", I don't think we'd be discussing this right now.

Re: That Tesla Data: What It Says and What It Doesn’t

#26

Post by majormajor »

tokenadult wrote: post #2

From the article, "Beginning early in the morning of my second day with the car, after the projected range had dropped precipitously while parked overnight, I spoke numerous times with Christina Ra, Tesla’s spokeswoman at the time, and Ted Merendino, a Tesla product planner at the company’s headquarters in California." That quoted sentence includes the interesting phrase "Tesla's spokeswoman at the time," seemingly i…

"Mr. Straubel said Tesla did not store data on exact locations where their cars were driven because of privacy concerns, although Tesla seemed to know that I had driven six-tenths of a mile “in a tiny 100-space parking lot.” 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. He did not share that data, which Tesla has now posted online, with me at the time."

That bit is particularly curious. Is being able to spring a "gotcha" on a reporter for publishing a "fake" review preferable to sharing the info with the reporter so that, if malicious intent is suspected, the reporter knows that Tesla knows exactly what the facts are?

The problems for Tesla here seems to be that the batteries don't like the cold (unsurprising this may be) and that the Supercharger network is still sparse at this point in time. Regardless of whose spin you buy, those points remain, and are good to know.

Re: That Tesla Data: What It Says and What It Doesn’t

#27

Post by avoutthere »

zeteo wrote: post #16

The logged data does support the broad lines of Broder's story (large drop in battery charge overnight, slow driving, turning down heating) and the 10-15% imprecision (driving at 52 mph instead of 45, heating goes down at 200 miles instead of 182, charge time of 47 minutes instead of 58) is well to be expected from what is a journalistic review and not a scientific experiment. So this all comes down to what customer…

I wonder if Tesla customer support recorded the calls.

Re: That Tesla Data: What It Says and What It Doesn’t

#28

Post by tedunangst »

jacquesm wrote: post #3

Two bits are completely non-sensical to me, is there any battery technician or otherwise knowledgeable person that can indicate in what conditions this makes any sense? > Beginning early in the morning of my second day with the car, after the projected range had dropped precipitously while parked overnight, I spoke numerous times with Christina Ra, Tesla’s spokeswoman at the time, and Ted Merendino, a Tesla product p…

Or are Tesla spokespeople and product gurus totally clueless?

Not entirely, but if your product has a known (tiny) glitch, and a reporter calls up with something that sounds like that glitch, what are you going to do? One obvious choice is tell them it's a tiny glitch of no consequence and hope you're right. In the best case scenario (tiny glitch), responses like "Oh, dear, it sounds like our car is underperforming" leave a bad impression too.

Re: That Tesla Data: What It Says and What It Doesn’t

#29

Post by codex »

jules wrote: post #5

> I was given battery-conservation advice at that time (turn off the cruise control; alternately slow down and speed up to take advantage of regenerative braking ) that was later contradicted by other Tesla personnel. What the heck? Does this guy seriously think that braking and then speeding up will conserve battery? Maybe the adage "don't attribute to malice what can be explained by stupidity" is true.

Had the reporter ignored Tesla's advice, the review would have been tainted. It's either "do what Tesla says, they're the experts" or "I'm doing to do my own thing sgainst Tesla's advice, invalidating all conclusions in this article." The journalist chose the former.

Re: That Tesla Data: What It Says and What It Doesn’t

#30

Post by jacquesm »

zeteo wrote: post #16

The logged data does support the broad lines of Broder's story (large drop in battery charge overnight, slow driving, turning down heating) and the 10-15% imprecision (driving at 52 mph instead of 45, heating goes down at 200 miles instead of 182, charge time of 47 minutes instead of 58) is well to be expected from what is a journalistic review and not a scientific experiment. So this all comes down to what customer…

> So this all comes down to what customer service might or might have not said over the phone.

Exactly, that is what I get out of it too. And that is probably conveniently unverifiable. Tesla really should repeat the trip with the same parameters as much as possible. Common sense dictates that if they waste power the way indicated that they should run out of juice and if they are conservative and follow the normal procedures that you could expect to observe when using any vehicle with a power source that depletes with use (which is all of them, including gasoline) that they should be able to complete the trip without a problem.

When driving in the North somewhere I came upon a sign that said 'no gas for 200 miles'. I had a half tank of fuel but I still drove back to the last town to make sure the tank was full. It seemed only prudent. In an electric vehicle with limited range and with a limited support infrastructure it would be folly to leave for a trip on a leg with an indicated range below the known distance to the next fuel source and to not know exactly where those sources are relative to the car and the planned route.

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