Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

wheels.blogs.nytimes.com

Post reply on HN
Print view View original

131–140 of 281 posts

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

#131

Post by ChuckMcM »

codex wrote: post #102
ChuckMcM wrote: post #94

Earlier quoted context omitted.

If I were to speculate, and I am, I would guess that the variable here is the temperature of the battery packs. Batteries are chemical power sources, and the chemical reaction which frees up electrons has temperatures where it works, and temperatures where it doesn't. (Hence "cold weather amps" as a selling point on car batteries). Anyway, I'd speculate that the Tesla person was thinking that if the battery got up to…

The battery's heating system likely drained the power overnight. The battery pack must be kept above a certain temperature or it will become irreparably damaged.

Do you have a reference for that? I ask because while I can imagine there are limits the kinds of things I've not seen one for Tesla's battery packs. I see that typical LiOn type batteries have a 'one month at -20C (-4F)' sort of limit, car batteries are typically better than that, good to -40F or so.

Edit: This article http://electronicdesign.com/power/operating-conditions-get-t... says "permanent damage at -50 degrees C" which is way colder than the lower 48. It's a good thought though, and I'm sure if you were connected to the wall at night the car would heat the batteries to an optimal temperature. Just not sure why it might do that without power available.

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

#132

Post by recoiledsnake »

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…

The major WTF moment for me was this:

> 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)

Someone failed at basic thermodynamics. Converting electricity to mechanical and back to electricity causes a terrible loss in power.

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

#133

Post by enraged_camel »

HelloMcFly wrote: post #112
enraged_camel wrote: post #67

Earlier quoted context omitted.

On the other hand, Brody has known record of exaggeration and distortion of truth. Whereas Musk is an honest, no-nonsense engineer. (Although I'd be interested if you could point me to a situation where Musk was caught blatantly lying about something.)

Musk is a business man and is concerned about marketing as much as anyone else. Here are his comments aimed toward the Volt: "Yet the state of the electric car is dismal, the victim of hyped expectations, technological flops, high costs and a hostile political climate.” Not exactly and objective view, or totally fair.

Uh, that was said by Broder in one of his previous articles.

http://www.nytimes.com/2012/03/25/sunday-review/the-electric...

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

#134

Post by frozenport »

nikcub wrote: post #42

The biggest mistake Elon made in his response was to dump all that data and to attempt to tear apart each part of the review. This means that the rebuttals now involve taking pieces of that and disproving them in the aim of disproving Tesla's entire argument. Tesla should have posted nothing more than a single line statement saying that Broder left the last charging station for a 65 mile trip with 32 miles on his ran…

Moreover it draw attention the problem, it is now a controversial car instead of a car with charge limitations.

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

#135

Post by lttlrck »

jacquesm wrote: post #23
surrealize wrote: post #9

Earlier quoted context omitted.

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 bat…

Are Tesla's customers all Tesla engineers? If not reproducing the run with a Tesla engineer is pointless.

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

#136

Post by lawnchair_larry »

vacri wrote: post #128
lawnchair_larry wrote: post #80

Earlier quoted context omitted.

You could probably go either way on that strategy. If you had this capability, and you suspected your adversary may be malicious, it is probably better to keep quiet and then destroy their credibility afterwards. If they are malicious, and know that they are being monitored, they might be more inclined to keep you blind to them. If Tesla knows that the monitoring can be disabled (it obviously can - how easily is the…

'turning it only on for X' is the same philosophy as having a back door in your software. "Oh, don't worry, only we will use it, and only for legitimate reasons. Trust us!"

I assume it has to be enabled with physical access to the vehicle, though I don't know this for certain. If they can turn it on remotely, then yeah, that's definitely bad.

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

#137

Post by lttlrck »

codex wrote: post #91
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…

He called early that morning complaining about the drop in mileage overnight. He was told the mileage drop was a glitch and to recondition the battery. When he called again, he was told to recondition the battery again--this time though a quick charge at Norwich. How many times should he call Tesla about the same problem, when he was told twice that the mileage was erroneously low? He had already attempted to recondi…

I sure hope Tesla has a Genius Bar in the pipeline.

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

#138

Post by nsfmc »

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…

"Never attribute to malice that which is adequately explained by stupidity."

You know, i like a conspiracy theory as much as the next guy, but this seems like a genuine series of errors, intentional or not, who knows.

But, let me play a separate angle to this, which is that when I read this article, I immediately flash-backed to all the tech support calls i'd had with relatives where each of us made some mistake or made some assumption given the facts at hand. "turn down the brightness, stop using the cd drive, turn off bluetooth, limit wifi usage, oh, wait, it's plugged in? ummm... time for a new power supply then!"

I don't know why we should expect the 'average consumer' to have deep insight into the workings of batteries or electric car technology. This stuff remains new and I think the point to be gained from this article is that it's still not totally obvious what causes some failures and not others. It'd be one thing if this guy really tore into Tesla, but he seems ambivalent more than anything else.

And reading that is basically the same reaction i get from my mom about my iphone: it's nice, but it's confusing to me and i still make mistakes each time i use it—nice, but not for me.

All our tech makes some assumptions about what you know and the effort you're willing to expend to get something to work. I don't think it's entirely unreasonable to step back and say "hey, something didn't work out and maybe that's a failure of the interface or our messaging or something" rather than jumping to claims of journalistic fabrication and oil conspiracies.

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

#139

Post by bmj »

jimmyyoung wrote: post #87
kdsudac wrote: post #57

I get why Musk feels like he needs to defend his company but I think he may be doing more harm than good on the PR front. Do you think the average Tesla customer is going to want to wade through a bunch of plots of battery charge vs distance, etc? I think the takeaway for the average Tesla customer might be along the lines of "hmm, this seems really complicated.... am I going to have to keep the heat down while I dri…

Musks blog post is meant to be technical. It's not directly towards the average Tesla customer. The average customer is probably not going to be following this. Thousands of newspaper are going to write an article everything that happens. They will make it more reader-friendly. Repeat: It is not Musks' intent for customer to read his blog.

The average customer is probably not going to be following this.

I wonder about that. I mean, if you are a Tesla customer (or a would-be Tesla customer), I reckon this story has come across your radar, given the sort of online media coverage. Certainly, the average customer may not read Musk's blog, but again, given that this story has been picked up by quite a few outlets on the web, I bet customers are reading it.

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

#140

Post by brisance »

smsm42 wrote: post #99
stcredzero wrote: post #47

> I do recall setting the cruise control to about 54 m.p.h., as I wrote. The log shows the car traveling about 60 m.p.h. for a nearly 100-mile stretch on the New Jersey Turnpike. I cannot account for the discrepancy, nor for a later stretch in Connecticut where I recall driving about 45 m.p.h., but it may be the result of the car being delivered with 19-inch wheels and all-season tires, not the specified 21-inch whee…

I think here the case is simple. Broder did not record his speed accurately, he just drove "around 45 mph", which very well might be actually 55 mph, on a good road with a good car 10 mph difference in speed doesn't feel at all. However, he can't just say "I didn't really collect the data accurately" since it'd hurt his credibility, so he mentions completely unrelated discrepancy in hope that most of the readers woul…

Or maybe he did report what the speedometer showed, and the calibration is off.
Post reply on HN