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Why Tesla Cars Aren't Bricked By Failing Batteries
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.'"
There seems to be a fundamental misunderstanding of the terms 'battery' and 'cell'. A battery is the collection of cells. So a Tesla could be bricked by a failed battery but it is tolerant to a failure of individual cells. This is not surprising.
Good thing slashdot is here to help us debunk everything I'd never have heard about from random dipshit bloggers.
>all that needs to be done is to tow the vehicle to a charger
Another claim was that the vehicles cannot be towed.
Powered by onion juice.
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.
"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!"
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?).
Electrolyte of Li-ion battery completely freezes somewhere around -30C. Degradation of performance (i.e. increase in resistance of the electrolyte and subsequent decrease of available power) starts sooner, but there are additives for that.
I guess there are few places on earth where a roadster is left parked for an extensive period of time in order for the whole pack to freeze.
Umm.. "Bricked" is a term for any phone that gets ... well.. "Bricked" as we call it..
It's been around since pre-iPhone.. phone modders have been unhappily bricking their phones for quiet a while to push it to its limits :-) iPhones, as usual, just made it "Popular"... the did not invent it.
The original post said bricked because that is exactly what the author meant. If you read it you will see this. He says if a car is left sitting long enough it will fully discharge and the car will be inoperable until the owner buys a new $40,000 battery pack from Tesla.
It's hard to believe that's how Micronians are made. Why don't we see it right now by having you both kiss one another?
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)
world was created 5 seconds before this post as it is.
AHA!!!! SEE? They admit it!!!
I'm a leaf on the wind. Watch how I soar.
"Bricked" is a term we used long before the iPhone for equipment finally failing to respond to any attempt to get it running again without any evidence of a physical damage. :)
I've seen many a bricked switch or router in my life which failed during an update attempt
Bricking didn't originate with iPhone jailbreaking and has been around for considerably longer. I can remember encountering the term for the first time while tinkering with a Linksys WRT-54g back in 2003 and it was already old by then.
Just because the iPhone can be bricked doesn't mean Apple invented the brick!
When you hear Lithium Ion Battery, you need to understand there are many different types of cell.
A battery consists of an Anode, Cathode and Electrolyte.
In LiIon based batteries, the electrolyte is a Lithium Salt, and the Anode is generally Carbon.
In LiPolymer batteries the electrolyte is held in a polymer of Lithium Cobalt or Lithium Maganese (this is the most common format of battery in consumer electronics)
In a recent project a for a hand held RF device, we chose LiFePO4. Mainly because it is so robust. Although it does not have the same capacity as LiPoly, you can grossly overcharge it and even drive a nail through it and it wont catch on fire. It also has much longer life over LiPoly.
LiPoly are very sensitive to overcharge, overdischarge, and mechanical damage, thus have a circuit to disconnect the battery when over discharged, thus the 'bricking' effect.
Tesla orginally used 18650 LiIon batteries with I believe had a LiCoO2 cathode, although I now think they are changing to pupose built cells. They would have a more sophisticated battery management that would prevent 'bricking'...... well at least one would hope...
46137
If Tesla is using 8000 cells, it is probably putting something like 6-12 cells in parallel packs, and then wiring up each of these packs of cells in series. The parallel cell packs provide the current capacity while the packs in series provide the high voltage required to operate the motors.
If an individual cell in a pack goes bad by having a degraded capacity, the capacity of the pack is degraded. However the pack can keep on operating.
If an individual cell in the pack goes bad by having a dead short a potentially catastrophic failure could occur as current from other cells in the pack flows through the shorted cell. There are probably fuses in the pack to prevent this.
The reaction of the BMS to such events will determine whether the car is dead in water or keeps on operating.
There are, of course, many more failure modes - the wiring harness of the cells could be bad, a bolt could come loose, the BMS electronics could fail and any of them could possibly cause the pack to go dead, till repairs are carried out. The engineers who designed this probably err on the side of safety, shutting everything down to prevent catastrophic failure..
Folks who don't understand what the term originally meant, now use it to describe any tech problem as bricked. As in:
"My browser says 'page not found' . . . my system must be bricked! I read that 'bricked' means 'not working' in the IT business . . . right?"
Schroedinger's Brexit: The UK is both in and out of the EU at the same time!
I never heard of rounded corners until the iPad.
cheers,
http://www.wired.com/autopia/2012/02/bricked-tesla-roadsters/
Wired contacted one of the owners, it can't have been too hard.
It seems Jaffe only speculated the five bricked cars only needed servicing. Jalopnik did the research and also got an admission from Tesla. http://jalopnik.com/5887265/tesla-motors-devastating-design-problem
Actually, "bricked" did not start with cellphones. It is a term referring to any electronic device that has stopped working. My first experience with it comes from early PCs, where people would talk about turning their PC into a "brick" or into a "doorstop".
The truth is that all men having power ought to be mistrusted. James Madison
Uh... you can easily burn out a lithium ion battery like the ones tesla uses by going below 1% charge. If their system isn't intelligent enough to completely stop battery use at 3%, and report that as 0, it's entirely possible to kill the whole power plant.
For instance, eventually I come across articles in the newspapers reporting some stories which I have witnessed myself. Every single one of them until today have had factual errors, and some of them quite gross.
I've been in the know on a couple situations (both personally and professionally) that were reported in the press, so I wanted to echo what you said. The media gets it wrong. A lot. It makes you wonder how many articles are factually incorrect for topics you aren't intimately familiar with.
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.
The truth is that all men having power ought to be mistrusted. James Madison
Yes, the claim seems to be actually true: http://jalopnik.com/5887265/tesla-motors-devastating-design-problem
When not plugged in or when plugged in with an unsuitable extension cord, the battery can run completely dry within a few days (one claim say that the battery can go from full to 50% within a week, another claim on that website says that according to Tesla, one car went from 4% to dead in a week).
I guess most people who buy an electric car will say "well duh, I know that when I have my car not plugged in, eventually the battery will be empty. I'll just have to recharge then". But I guess also most people will not know that the battery will be DEAD, as in "you have to get a new one, this one's DESTROYED" when it goes to zero charge.
Having a battery which can be destroyed in a matter of days if the car is not plugged in is a pretty big issue. An issue people really need to be made more aware of. Go on holiday and leave your Tesla at home? You better ask a friend to check every couple days if the car is still charging. Or what if you park your Tesla at an airport, plan to leave it plugged in there for a week, but on the first day you're gone, some kid unplugs the car "for the lulz"?
If you can repair an item just by changing its battery, it's not bricked.
Give me Classic Slashdot or give me death!
Slashdot is losing it (whatever it is). This article is pure Tesla Co. press release.
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%.
Why is everyone reacting like this is a new concept with vehicles? I bricked my '76 Plymouth Duster when it threw a piston rod through the sidewall of the engine one time. I nearly bricked a horse while walking him through a rocky-bottomed stream when he slipped. The motive force in any mode of transportation is susceptible to going down and effectively making you put wear on the soles of your shoes -- but the electric car will eventually be more reliable (far fewer moving parts and no need for hay/oats or brushing) and it will be far more ecologically sound (less need for oil derricks and belchy/gassy large animals). -- Ace
Tesla motors does not deny the fact their batteries can be bricked. They say they have done much to prevent it from happening yet you can destroy the battery pack in much the same way you can destroy a motor if you attempt to run it with no oil. Because the battery pack is composed of many cells both in parallel and in series it is impossible to just unplug it. The pack will always be using power because the cells are in parallel. And because they are in parallel they will always die out if left alone. It is not a problem though in most cases. You must use the car in the way it was designed to be used. Likewise with a normal automobile you must take into account oil, timing belts, water pumps, etc.. Bricking is possible. Know the problems and know how to work around them.
Just what we need--more "analysts" fighting bad bloggers' bad information with more bad information.
Let's start with the "more than 8000 individual batteries". These are 18650 cells (a standard form factor, a bit larger than an AA cell), and a Roaster has only 6831 of them. They are not "individually managed". Rather, they are grouped into a 69-parallel module, with 99 modules in series. (69x99==6831)
It is asinine and a distraction that Tesla (and everyone else) constantly obsesses about the 6831 cells. For all practical purposes it is a 99-cell Li battery, but rather than using monolithic cell modules, Tesla (like ACP before them) builds modules from smaller component cells, because they yield better cost ($/Wh) and specific energy (Wh/kg), with more-favorable cooling and safety characteristics.
Other than a built-in per-cell PTC device (which Tesla is likely no longer using), any "management" is done at the module level, and the battery is treated as a 99-cell series pack. The PTC is a passive cell protection device, designed to save a cell from a failed-short condition, but they also cause as many problems as they prevent.
Secondly, the "solution" is not nearly as simple as "shutting the pack down" when it reaches "an extremely low depth of discharge".
The Li cells themselves do not discharge themselves quickly when idle--perhaps 5 or 10 percent per year. However, small parasitic (e.g. maintenance) loads will slowly deplete the cells' energy. Herein lies the "grain of truth" that is probably at the center of this greatly dramatized "journalism".
Li traction batteries typically have on the order of 100 cells (or more for 600V systems), and each cell must be monitored to keep its voltage and temperature within a safe range. Typically the monitors are powered from the cell modules directly, and the competing design constraints are many: Small packaging, low cost, low power, electrical isolation, and so on. It is possible, but not trivial (nor cheap) to make a cell monitor draw zero current when its host module is at low voltage.
The original rant (er, blog) claimed that the parasitics would deplete a battery in 11 weeks, which is bordering on implausible, and if true, it would represent a staggeringly high rate of self discharge. Per Chelsea Sexton (who knows what she's talking about), there has not been "a single 'brick' story that didn't involve some extraordinary circumstances".
Lastly is the notion that the traction pack is necessarily destroyed by a deep discharge event. While it is true that deep discharge (and particularly cell reversal) will cause some permanent damage, the damage is in the form of higher impedance, and this is far from rendering the module useless. The battery can be brought back via trickle charging and a per-module impedance test will reveal if any are too far gone.
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.
A proper battery management system will shut down absolutely everything (including itself) when the battery is approaching full discharge. In that state, there's no reason the battery pack shouldn't be able to go for a year or two without reaching the point of failure.
Likewise, a proper system would allow the management system to power back on (reboot) when the car is plugged in, and then begin recharging the battery.
The cheapo protected 14500 (AA sized) LiIons I use here have that feature. The disconnected discharge rate is a few micro-amps. If I run it "flat", I can stick it in a charger days or weeks later and charge it back up. Apparently, the Tesla never actually shuts down standby systems and as a result the battery can be irreparably damaged by sitting for 11 weeks (if starting from a full charge) or much less (if the car was driven before sitting).
Other electric and hybrid vehicles do the right thing and go into total shutdown when the battery gets too low. Then you wake it up by plugging it in.
This isn't a general problem with electric and hybrid vehicles, this is a glaring design flaw in the Tesla.
Unless you want to use another term, a $40k bill to get it running again is fairly bricked.
The original blog poster has a $40,000 quote, and the Tesla manual clearly states that the battery system will require replacement if depleted and not immediately recharged after entering range mode or running to 0% in reserve. They're worried enough about this that they instruct you to contact them immediately if you cannot charge your car.
Read the comments at ITWorld.
This should surprise just about no one, but, frankly, Tesla should have a low-charge relay pull or a manual lever for battery disconnect. Tesla doesn't appear to be arguing the point that their systems can fail in certain conditions, requiring costly replacement. Heck, they put it in the manual.
Simple answer: plug in your car.
And, yes, I still want one.
Having RTFA'd, it is a negative opinion piece full of half truths and misinformation. That article is a horribly blatant attempt to discredit the vehicles from somebody who does not understand the underlying technologies. It needs to be taken as an opinion piece - there are zero references on his five examples (it's simply a chat with a service manager), and he is stating things as fact which simply aren't.
:P
First: yes, there are cases with batteries where they can be discharged to the point where the cells themselves are damaged and cannot be recharged. This is the case with *most* battery chemistries and is not going away any time soon. The blogger calls this a "Devastating design problem" when it is simply a part of the technology, like not storing your fuel cans near the furnace or leaving fuel to sit in a carburetor. There is a pretty clear warning in the car's manual not to let the battery voltage flatline for long, our intrepid blogger even provided a a PDF file with that page out of the manual. It states that the battery must be charged immediately if the charge level falls to 0% and has a great deal of information on the care and feeding of the battery.
Even if we take the five failed battery packs as truth, that is 0.2% of vehicles with an issue - an issue that in each example was due to the owner not charging the vehicle with one possible exception. His extension cord example could present a possible issue with the Tesla chargers. A typical cheap "heavy duty" extension cord will have 16 gauge wires, which over that distance is going to have some noticeable resistance. I don't know the current draw of the battery, but if it is expecting to pull 10 or 20 amps, the charger will see a significant voltage drop and likely cut off the charging (unless it has a "trickle charge" mode, dunno...). If the vehicle didn't report that it wasn't charging (or inaccurately reported it was), then I could see this being a design issue. I'll also note that this particular example did not state whether the customer had to pay for the repair.
What it comes down to is all electrical systems have ways they could be improved. That doesn't make this a devastating problem, it is simply an aspect of this class of vehicle that the owner needs to pay attention to. This blogger has a bone to pick or wants to stir the pot with a sensationalist report. Apparently it's working, after all, we both read his article
+1 Disagree