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Inside a Tesla Model S Battery Pack

teslamotorsclub.com

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Re: Inside a Tesla Model S Battery Pack

#71

Post by [deleted] »

bigiain wrote: post #55
greglindahl wrote: post #41

Earlier quoted context omitted.

Archive.org respects robots.txt. Nothing unilateral about it.

How many of the webforums you post on give you access to update the robots.txt file to inform Internet Archive about your copyright desires? Like I said - I'm conflicted about this, I _want_ these images to be available, and whatever the guy wrote in his forum post we know Google (and Blekko!) will index and download them and will pretty soon be causing them to be "otherwise distributed outside of this forum" - but t…

[deleted]

Re: Inside a Tesla Model S Battery Pack

#73

Post by lotsofmangos »

zizzer wrote: post #64

Anyone else notice that in the Tyco contactor picture it's labelled "Coil 3.14 Ohms"? It makes me think they only needed it to be 3 Ohms, but an engineer somewhere couldn't resist making it πΩ

It might be to normalise other components to nice units, given that pi turns up when calculating the inductance of a coil.

Re: Inside a Tesla Model S Battery Pack

#74

Post by jacquesm »

hellgas00 wrote: post #35
jacquesm wrote: post #26

That was one very quick trip to the recycler, pack dates from August 2013. Crashed car? Totally nuts to work with DC voltages this high without taking safety precautions. Anything over 50V DC is to be treated with very serious respect. AC is different, you get a good number of opportunities to dis-engage, but with DC your muscles contract and that's that. I'd rather mess with 2 KV AC than with 200 V DC. Lovely engine…

Not sure where this myth started, the idea that somehow AC is less dangerous to handle at high voltages over DC. Wall socket AC alternates at ~50Hz, that's an oscillation every 0.02sec, for perspective, the average human reaction time is in the range of 0.15 to 0.3sec [Wikipedia]. There almost no chance that you willingly disengage a circuit once it's made for both high voltage AC or DC. Be careful whenever handling…

I've been doing a ton of reading on the subject because my unsourced and out-of-hand rejection of what you wrote did not sit well with me, and you may very well be right after all.

Apparently the DC current required is 10 times higher to do comparable damage than the AC current. This is totally at odds with both my first-hand experience and a ton of interaction with professionals. So I'm a bit confused now, there is a whole pile of literature out there that says one thing and then the wikipedia page claims the factor of 10 going the other way, citing a book that I don't have access to.

The fact that the electrical chair is AC was possibly a hint, but the electrical chair was developed during the 'current wars' by the AC proponents. (I'm not sure if they tried to convey the idea that AC was more dangerous that way, it seemed to have been an ill thought out decision from a marketing point of view.)

I'll keep looking and reading to see if I can find an authority that decisively claims either the one or the other.

The factor of 10 seems hard to believe, to generate a 30 mA current through a human body at 230VAC would become 2300V DC for a 300 mA current through that same body (per Ohms law), that's ~800 Watts delivered versus ~80.

2300V 300mA sources are hard to come by but a 600V DC source that can do only a few mA will blow you clear across the room, which makes me wonder what would happen if you happened to interact with a source that is capable of substantially more than that. This would also mean that a 300V DC source such as that battery pack should be perfectly safe to work with but I don't believe that's true for even a moment.

So, my apologies for the unsourced rejection of your claim, to be continued.

Re: Inside a Tesla Model S Battery Pack

#75

Post by jacquesm »

tokenadult wrote: post #43
dublinben wrote: post #42

Earlier quoted context omitted.

I've never seen such an aggressive and hostile copyright notice in a forum signature before. It's not entirely clear that you can even claim copyright over trivial online comments.

It's not entirely clear that you can even claim copyright over trivial online comments. Trivial or not, you have copyright in your own writings, online or off-line. Each participant on HN owns the copyright in the written expression of his or her comments. Similarly, a photographer has copyright in photographs taken by that photographer. See a user profile of a high-karma HN participant https://news.ycombinator.com/u…

Good luck enforcing such a claim. The damages part will be especially interesting.

Re: Inside a Tesla Model S Battery Pack

#76

Post by cc439 »

v13inc wrote: post #19
Gracana wrote: post #7

Interesting to compare this to the ford fusion battery[1], which uses clever construction to prevent a technician from being exposed to high voltages during construction and teardown. [1] http://www.etotheipiplusone.net/?p=3109

That almost looks like it was built by a mechanical engineer, not an electrical engineer. All the effort seems to be focused on building a sturdy case for the batteries, and the actual electrical connections are all steel screw terminals and crimping, without any spot welding anywhere. I'd be worried about the electrical resistance of all those contacts, and the heat it produces. Tesla's battery pack seems like a mor…

Having a mechanical engineer drive the design of a battery pack isn't necessarily a bad thing, IMO it's the sensible route for a mass-market car made by a mass-market company.

Modern high volume, quality focused manufacturing will often prioritize ease of assembly over elegance in design. Fewer, simpler steps make for fewer defects and greater product consistency. It's the whole "lean manufacturing" ideal at play, done right it will lower costs and improve quality to a point that you can splurge on a little engineering elegance such as a small-volume hybrid model capable of being assembled on the same line as your high-volume offerings. Tesla doesn't have to worry about this for now as they compete in a high-margin segment of the industry and they are trying to set a benchmark of excellence that will create demand for their products.

A real world example I've seen in person is the Nissan Leaf. The battery is designed to be as safe as possible for handling by a line worker and that allows Nissan to produce the Leaf at the exact same time as plain vanilla Altimas are rolling down the line. If you ever take a tour of their Smyrna, TN plant you'll see 1 line with a 9 or 10 Altimas interspersed with a Leaf every once in a while. It's smart engineering at a production-level viewpoint as a "worse" battery allows an entirely different product to be produced with minimal production overhead.

Re: Inside a Tesla Model S Battery Pack

#77

Post by greglindahl »

bigiain wrote: post #55
greglindahl wrote: post #41

Earlier quoted context omitted.

Archive.org respects robots.txt. Nothing unilateral about it.

How many of the webforums you post on give you access to update the robots.txt file to inform Internet Archive about your copyright desires? Like I said - I'm conflicted about this, I _want_ these images to be available, and whatever the guy wrote in his forum post we know Google (and Blekko!) will index and download them and will pretty soon be causing them to be "otherwise distributed outside of this forum" - but t…

The photos aren't on the forum, they are on an image hosting website. Other images on the forum are hosted on the forum. If the guy knows how to host his images elsewhere, he should be able to figure out how to host the images someplace with a robots.txt that he likes.

Re: Inside a Tesla Model S Battery Pack

#78

Post by glurgh »

jacquesm wrote: post #74
hellgas00 wrote: post #35

Earlier quoted context omitted.

Not sure where this myth started, the idea that somehow AC is less dangerous to handle at high voltages over DC. Wall socket AC alternates at ~50Hz, that's an oscillation every 0.02sec, for perspective, the average human reaction time is in the range of 0.15 to 0.3sec [Wikipedia]. There almost no chance that you willingly disengage a circuit once it's made for both high voltage AC or DC. Be careful whenever handling…

I've been doing a ton of reading on the subject because my unsourced and out-of-hand rejection of what you wrote did not sit well with me, and you may very well be right after all. Apparently the DC current required is 10 times higher to do comparable damage than the AC current. This is totally at odds with both my first-hand experience and a ton of interaction with professionals. So I'm a bit confused now, there is…

>by the AC proponents.

By the DC proponents. Or AC opponents. Definitely part of a long campaign to try to make AC appear dangerous.

Re: Inside a Tesla Model S Battery Pack

#79

Post by secabeen »

dublinben wrote: post #42
bigiain wrote: post #28

Earlier quoted context omitted.

His copyright notice and explanatory paragraphs make it clear he's trying to keep some level of control over those photographs, while still sharing them with "his community" - which means I feel a little uneasy about having archive.org unilaterally slurp the images up like that... I know it's kind of a losing battle, but "publicly available" does not mean "in public domain".

I've never seen such an aggressive and hostile copyright notice in a forum signature before. It's not entirely clear that you can even claim copyright over trivial online comments.

There's a history of buzzfeed and other link-farm sites writing inflammatory posts based on TMC forum posts. Many posters don't want their content stolen that way, so they put on those notices.

Re: Inside a Tesla Model S Battery Pack

#80

Post by njharman »

clumsysmurf wrote: post #8

From what I've read these packs have around 7000 3100mAH NCR-18650s. Over the years I've used these NCRs (or lower mAH versions) individually in special flashlights - and while they seem to have good reliability overall, one did fail on me while charging. Thats why often hobbyists charge these outside in fireproof bags. I would be terrified to drive a car with this technology.

I've set off cans of gasoline (Disclaimer: I was teenager and thus stupid).

I am not terrified to drive a car with that technology.

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