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Power Transportation

Why Tesla Cars Aren't Bricked By Failing Batteries 362

Posted by samzenpus
from the not-do-fast-now dept.
itwbennett writes "Don't believe recent claims made by a blogger that non-functioning batteries in the Tesla Roadster cause the electric cars to be bricked, says IDC analyst Sam Jaffe. 'Here's the primary fact that the blogger in question doesn't understand: the Tesla battery pack is not a battery,' says Jaffe. 'It's a collection of more than 8,000 individual batteries. Each of those cells is independently managed. So there's only two ways for the entire battery pack to fail. The first is if all 8,000 cells individually fail (highly unlikely except in the case of something catastrophic like a fire). The second failure mechanism is if the battery management system tells the pack to shut down because it has detected a dangerous situation, such as an extremely low depth of discharge. If that's the case, all that needs to be done is to tow the vehicle to a charger, recharge the batteries and then reboot the battery management system. This is the most likely explanation for the five 'bricks' that the blogger claims to have heard about.'"
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Why Tesla Cars Aren't Bricked By Failing Batteries

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  • by larwe (858929) on Thursday February 23, 2012 @06:45AM (#39134947) Homepage
    It's a shortcoming of LiIon technology that if the cell becomes over-discharged, the cell may fail short circuit, and a subsequent recharge may cause an "exciting" failure (think flames). That's why all LiIon packs have a protection circuit that permanently disables the pack if it's discharged to the danger zone. Given the massive size of an automotive battery pack, it's easy to believe they have some very conservative safety devices in them. And it's also easy to believe that the cost of individually testing/replacing cells and "rebooting" the protection circuitry in a pack that has tripped its safety limits is prohibitive.
  • Weak! (Score:2, Interesting)

    by Anonymous Coward on Thursday February 23, 2012 @06:46AM (#39134951)

    "The battery management system of the Tesla Roadster keeps the battery from being discharged to a damagingly low state of charge under normal driving conditions."

    One of the original points was that if the car was left alone for a relatively short period of time then it would discharge fully due to physics, nothing the power management system can do about it.

    This is a pathetically weak rebuttal to be honest. Take each one of his points and give us a counter-point to each one. So far it seems to be "He doesn't know what he is talking about, ner-ner!"

  • by Jack Malmostoso (899729) on Thursday February 23, 2012 @07:03AM (#39135019)

    When I read the blog article I thought exactly the same thing. Cells left to self-discharge will not go below their thermodynamic equilibrium, which is more or less the potential at which they are built (remember, Li-ion batteries when assembled are discharged by nature). There is no danger of damaging the cells when self-discharge occurs.
    Another issue is when the cells are actively overdischarged, however a Li-ion battery is more likely to explode due to overcharge (plating of Li metal at the negative electrode) than overcharge (insertion of too much lithium in the cathode and electrolyte depletion).

    Most likely the BMS is refusing to come back to life unless hooked up to a secret Tesla computer, but I guess the packs can be refurbished.

    Also, kudos to the idiot recharging the car with a 30m cable extension (that's what 100 feet is, right?).

  • Re:Tow? (Score:5, Interesting)

    by Jack Malmostoso (899729) on Thursday February 23, 2012 @07:06AM (#39135031)

    Well technically towing an electric vehicle, missing a clutch, would make it a generator, which could possibly damage the battery. However there is a youtube video showing a Nissan Leaf being towed and the battery being recharged. Don't try this at home!

    Another option with the Tesla could be to lift the back wheels and tow it with the front wheels on the ground, unless there is some regenerative braking system which still acts as a generator. And yes, you want to lock the wheels if you do that.

  • Re:"Battery" (Score:5, Interesting)

    by gl4ss (559668) on Thursday February 23, 2012 @07:12AM (#39135067) Homepage Journal

    the IDC analyst isn't "just a blogger", it's a guy who's trying to write a rebuttal to sound cool, but too bad he didn't actually go and try to look for the actual cases - instead he's just going "can't happen because of pr materials a, b and c". if he starts with that a battery of batteries can't have anything wrong with it by design.. comes off almost as a fanboi who didn't even read the news piece about the blog posting(which states that you can't even tow them, which sounds a bit strange but not _that_ strange if it won't fire up any elecs. of course you could tow them still lifting it on a truck or whatever)

  • Re:battery vs cell (Score:4, Interesting)

    by robbak (775424) on Thursday February 23, 2012 @08:48AM (#39135473) Homepage

    Teslas are also designed to avoid deep discharge: read the article! You would have to discharge it and then leave it parked for months to damage enough cells of the battery, but that would be yoru fault.

  • by Attila Dimedici (1036002) on Thursday February 23, 2012 @09:34AM (#39135697)
    Actually, the "rebuttal" article seems to say that yes, the battery will become unrechargeable if you leave your Tesla car unplugged for too long....which is what the article it is "debunking" says as well.
    The first article says, "This is a problem and Tesla should do something about it." The second article spends three paragraphs explaining that the original article gave a simplified explanation of how the Tesla works and is wrong about the possibility it discusses and how something the original article never said can't happen. Then it spends a paragraph explaining how the problem the original article actually talks about can indeed happen and how that is the nature of rechargeable batteries and there is nothing Tesla can do about it. Finally it spends another paragraph talking about how the original article is one of many that is spreading misinformation about electric vehicles.
  • by d3ac0n (715594) on Thursday February 23, 2012 @10:05AM (#39135859)

    Or he's NOT and you are just assuming he is because you either dislike the blog/blogger or are utterly ignorant of the facts. The communication emails are public knowledge, and the 40 grand cost is NOT "made up from whole cloth" and has been confirmed by Tesla.

    Geez, people, RTFA for crying out loud.

    Jalopnik article on the issue:

    http://jalopnik.com/5887265/tesla-motors-devastating-design-problem [jalopnik.com]

    Jalopnik article about the attempt to smear the whistleblower:

    http://jalopnik.com/5887499/who-is-trying-to-smear-the-tesla-battery-problem-whistleblower [jalopnik.com]

    Gallery of screenshots of emails:

    http://jalopnik.com/5887504/tesla-emails-gallery/gallery/1 [jalopnik.com]

    Read read read. Then rethink and reassess.

  • Re:battery vs cell (Score:3, Interesting)

    by polebridge (517983) on Thursday February 23, 2012 @10:09AM (#39135893)

    > not semantics, but rather proper use of terminology
    Wait, isn't that exactly what semantics is, the proper use of terminology?

    "When I use a word," Humpty Dumpty said in rather a scornful tone, "it means just what I choose it to mean -- neither more nor less."
    "The question is," said Alice, "whether you can make words mean so many different things."
    "The question is," said Humpty Dumpty, "which is to be master - - that's all."

  • by Golden_Rider (137548) on Thursday February 23, 2012 @11:04AM (#39136439)

    If you can afford a Tesla, you can afford to RTFM and get a trickle charger.

    Probably (although I am sure that many people who have enough money to buy one won't read/understand all the technical stuff and will want the car to "just work") - but that still leaves us with the point that the battery pack can go kaputt within a couple days if the car is not charged (if the car was already at low charge) - which is something which needs to be communicated to customers far more clearly than just a sentence here and there that it is not good to let the battery go completely flat. Because I am sure that for almost every person who is not very familiar with battery technology, the EXPECTED consequence of a flat battery would be "recharge it again and you're good to go". If there is the possibility of making a $40k mistake, I'd expect the car to go full "star trek red alert" on me when I park it somewhere at less than 10% charge, and to start sending "help! I am dying!" SMS when the battery goes below 5%.

  • Re:battery vs cell (Score:5, Interesting)

    by guruevi (827432) <evi.smokingcube@be> on Thursday February 23, 2012 @11:46AM (#39136849) Homepage

    Ever found an old cell phone in your night stand drawer or wherever? I recently found one from the early 90's (almost 20 years old) and the thing still had a 1/2 charge left and worked. Battery cells take forever to self-discharge and at that point there will probably be more damage to other parts of the car because it's been standing still so long (corrosion, plants growing in or through the body, rodents nesting and chewing through cables) that maybe you should just scrap the car.

  • Re:battery vs cell (Score:5, Interesting)

    by radtea (464814) on Thursday February 23, 2012 @12:33PM (#39137391)

    Remember: Bricked = Failed and unrepairable.

    This is a curious belief. I presume you've not been around embedded technology enough to have ever heard the term "unbrick", which is what people who actually understand the term "brick" used to describe the process of recovering from a bricked state.

    According to your incorrect belief such a term could not possibly exist. And yet it does. So either the world is full of embedded engineers who don't know what they are talking about, or you are simply announcing to the world your own ignorance. Which is kind of useful: everyone here claiming that the Tesla is not "really" bricked by being left uncharged for a few months--as might easily happen to a vehicle in storage, being shipped somewhere, or simply parked near an airport during an extended vacation--is identifying themselves as having nothing useful or interesting to contribute to the conversation.

    Likewise, people claiming that "this can't happen because power management" are declaring their ignorance of electrochemistry, which goes on regardless of external circuitry. Electrochemical cells that are not being actively charged can and do continue to discharge all by themselves regardless of anything any external circuit does. Some types of cell can and do get themselves into an unchargable state after sufficiently deep and prolonged discharge, regardless whether the discharge is passive or active.

    So this "refutation" of the claims against Tesla is nothing but hand-waving anti-scientific bullshit: it is saying, "What has actually happened cannot possibly have happened according to my understanding, and my understanding cannot be wrong so the facts must be wrong." This is no different from the people who claimed that Galileo couldn't have seen the moons of Jupiter because just as there were seven seas and seven openings in the human skull so there could be only seven wandering stars.

    There is a lot of this kind of anti-scientific reasoning about. I recently saw a claim that the Heartland Institute's campaign against second hand smoke laws was based on the "reasoning" that second hand smoke wouldn't be breathed deeply into the lungs and so couldn't cause lung cancer, regardless of the actual empirical data that shows second hand smoke causes lung cancer. This is not "reasoning" in any Bayesian sense: it is gibberish masquerading as thought.

    The same kind of gibberish seems to be all that defenders of Tesla can come up with here. If anyone really believes they can't brick their Tesla by fulling discharging the battery they should drive it to the point of full discharge and let it sit for a while. That would give us new facts to account for, and actually contribute to the resolution of this question.

  • by laing (303349) on Thursday February 23, 2012 @01:09PM (#39137873)
    Laptop batteries can indeed discharge to the point where they are bricked. This seems to be a characteristic of lithium cells.

    I've had this happen myself with several Toshiba laptop batteries that I left in a unplugged laptop for several weeks, and a friend of mine had to pay Apple for a new battery when his Macbook-Air was unplugged for a month (while he moved).

    In the case of my Toshiba batteries, I was able to open up the two battery packs and construct one working pack from the remaining good cells. The bad cells were unchargeable. (I did this because Toshiba wanted $150 for a new battery pack and I was poor at the time.)

    All of these cases involved lithium battery arrays connected to a battery management system where each cell is individually monitored for temperature and charge state.

    The Tesla article may be bogus, but it has a ring of truth for me because of my experiences above.

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