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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.'"
>all that needs to be done is to tow the vehicle to a charger
Another claim was that the vehicles cannot be towed.
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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?
I would have to assume that a Tesla wouldn't be "bricked" by a failed battery either, as the batteries are presumably replaceable by the manufacturer.
Remember: Bricked = Failed and unrepairable.
Finally had enough. Come see us over at https://soylentnews.org/
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
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
No, not semantics, but rather proper use of terminology. The AC is correct - a battery is a collection of cells. A battery pack is a collection of batteries. (The battery being the smallest individually replaceable part in the pack.)
That's why a "D" cell battery is called a "single cell battery" - because, duh, there's only a single cell in the battery. That's why automotive type batteries (of the type you add water to) have multiple vent caps - because each individual cell must be separately vented and/or topped off with water.
The quoted IDC analyst adds to the confusion (at least to those of us versed in standard terminology) by using the terms battery and cell interchangeably, which is the same mistake often made by the general public - you for example.
Once the bank of cells does go below the detection level, it is still possible for them to still discharge further, depending on the condition. But they should wire the battery pack management system in such a way that it can be powered itself by other means than just the battery pack it manages. When the charge connection is plugged in, it should be made so that a low level of power is provided to bring the management system up without it being powered from the pack. At this point, it should be able to test the battery pack condition to determine if it can be charged back up safely or not. If Tesla didn't think of it, their bad.
now we need to go OSS in diesel cars
Except this has been making the rounds, not just a dipshit blogger
http://jalopnik.com/5887265/tesla-motors-devastating-design-problem
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.