Does anyone *know* what cause(s) of recent/historical battery fires (in EVs, particularly)? I assume it is not related to abuse or "usage hazards". Or, charging/BMS. But, rather, originates in manufacturing (?)
Is this an issue with material (im)purities, mechanical defects, assembly faults, etc.?
Said another way, is this a problem that has its cause at the factory or after-the-sale? (or, somewhere in-between)
My guess is that it is going to be due to dendrite formation, leading to more rapid self-charge, which will lead to the core of the battery getting hotter than ambient, and even more rapid self-discharge.
At some point the process of self-discharge and self-heating will presumably run away, and the battery will get hot enough for the cells to burst and catch on fire.
I'd have imagined that batteries big enough for this to be a real risk would come with at least one temperature sensor at the core of the battery, and a microcontroller to read the sensor, process the data and warn the user, but I've not seen anything to suggest that people are actually doing this.
You'd need a temperature sensor if you want to use the voltage across the battery as much of an indicator of it's state of charge, so it ought to be a pretty obvious idea.
I'm not sure that there is one single cause.
Not necessarily a manufacturing problem so much as the intrinsically high energy density in such a battery when fully charged. It can fail various ways because of the high voltages, low internal resistance and peak currents involved.
A fair proportion are provoked by high speed impacts. The others seem to include thermal runaway in cells that were not adequately protected by their thermal cutout for whatever reason and/or release valve failures.
I have yet to see an EV on fire myself. I see an ICE on fire by the roadside about every other year doing a fairly high mileage (lower now).
Part is the huge number of ev vehicles on the road now.
Both reactants very close together, with large-scale chemical exchanges every day.
I have never seen a car burning, or even a burned-out one on the side of the road. In a junkyard maybe.
I hope BEVs are adopted sooner, rather than later so we can get rid of the scourge called gasoline.
Well, that would be "information", too!
What I'm getting at is where efforts could/should be directed to address this.
E.g., if it was due to impurities in the materials used, then better "refining". If due to high charge (regen braking)/discharge rates, better battery/load management. If due to mechanical damage ("collisions"), better physical protections.
I'm also wondering how the issue might play into recycling efforts. As the raw materials become more difficult to acquire, I suspect that will see more attention.
We "know" how lead-acid batteries fail. And, can largely recycle their materials without worsening that failure rate. Will the same hold for these EV batteries? Or, will they effectively become "scrap" (again, depending on how the failures manifest)
That would seem to be addressable by design changes...
I suspect that is related to the distribution of ICE vs EV products out there. I can only claim to have seen (first hand) a single engine fire in a lifetime of driving. Though I have seen burnt out hulks (often "getting a ride" to <someplace>).
[P.S. Did you finish your research/paper?]
That *sounds* like it could be easily corrected, going forward (unless there is something that makes that particular aspect of manufacture "troublesome")
It's mostly QA/QC problem, but the troubling part is that it was not discovered until 100,000 Bolt batteries were already made.
The Market is good for "teaching lessons". Hopefully, they have learned from that and won't let any other problem that *can* be caught in QC plague them, again. I.e., they *have* a means to address THAT problem.
Yeah, like that is a lesson anyone needs to "learn". Every car line has problems and recalls. BEVs are no different. Obviously you don't remember the Pinto gas tanks or the Vega engine problems, or the Corvair handling problems, or the...
The auto industry has done a lot better over the decades, but we still mess up. What was the name of the air bag maker, Tanaka? They went into Toyotas and many other brands. Then there was the Pentium floating point bug... wait, that's a different industry.
Imagine ONE Tesla fire (it's pretty bad - everything but steel burns). Now, imagine an ENTIRE PARKING LOT of hundreds of Teslas (or other EVs) burning, which is Ricky's vision for tomorrow.
Can't be any worse than the garage fires we've seen with ICE vehicles. They are a bitch to put out, requiring special foams and such. At least a lithium ion battery fire only requires water.
We won't have to worry about electron tanker trucks overturning on the highways every day. We already have a national electron distribution system that seems to be very, very safe.
Just today I was driving my Tesla on the highway and had to switch the ventilation to recirculate because of the noxious fumes from a truck in front of me. It will be so nice to get the stinky, filthy petroleum engines off the road.
Stink-be-gone!
Not exactly. It's what Flyguy imagines to be Rick's vision for tomorrow. Flyguy has a fertile imagination and no grasp of reality at all.
There are parking lots full of hundreds of Teslas - at the Tesla factory - and they don't seem to burst into flames. Maybe if we freeze-dried Flyguy, and crushed him to powder, we could sprinkle the powder over a few EV's and see if they caught on fire. I don't see why they should, but it is clearly an experiment worth trying.
I think the problem is in short that in a high power battery you have a lot of stored potential chemical energy and a very thin barrier separating reactive components. It doesn't take much for them to go wrong.
I think the lithium will be fully recyclable but the electrolyte is probably spent or simply not worth the effort at end of life.
If necessary zone refining can get anything pure again. I doubt that the purity of the electrodes or electrolyte is an issue. The right magic ingredients to keep it all long term stable will be though.
Do you remember the chaos cause by the Chinese knock off capacitor recipe stolen from Murata that went haywire after about 5 years (by which time the damn things had been built into vast numbers of PC motherboards).
I expect they will get better. The trouble is that pressure release valves wet with electrolyte have a nasty habit of gumming up when it dries and are much less willing to open the second or third time around.
My instinct is that superfast charging and the associated rapid battery temperature rise has to be bad for the battery longevity no matter what the sales droids and marketeers may say. ISTR some models you can only super fast charge them every few months.
I am slightly mystified how a car that has been recently running flat out can be safely charged at all without impacting longevity. Our Dyson vacuum cleaner the battery is too hot to touch after 20 minutes use and recharging it in that state leads to total capacity failure in under 3 years from new. The replacement Chinese clone battery comes with a warning to let the thing cool down *before* putting it back on charge.
There are not that many EVs where I live up North. Hardly any charging points either and several high profile unfinished big charging sites that have been waiting for an electricity supply for nearly a year now!
It is in its final revision. First version insufficient performance and numerical analysis - second draft too much. It has split into two possibly three related papers as a result of becoming too long. I now have an i5-12600 which has changed performance markedly from a 3770.
Dotting i's and crossing t's in the final revision step is a bit tedious so it has taken some time. There is an obvious follow-up using a related cubic method for hyperbolic orbits e>1 that I am now starting work on.
I have found some very interesting compiler behaviour in the process of benchmarking the underlying code too - which I should also write up. MSC
2022 can run rings around all the other compilers I have tried.But it requires you allow fastmaths and every coding extension that your CPU supports and critically in "Advanced" set the calling convention to vectorcall /Gv (and if necessary adjusting your code to suit it).
Otherwise the code follows the old _Cdecl convention of returning the FP result on the x87 stack. Doing most of the work on the SSE or AVX512 FP hardware and then slams the result onto the stack so that it can load it into x87 ST(0). This creates a pipeline stall since the value cannot be loaded immediately and worse since the stack is only 8 byte aligned you get additional performance hits if the write spans a cache boundary.
I have a new precision cube root algorithm that came out as a side effect and is faster than all existing methods. It relies on the way that speculative and out of order execution can effectively parallelise independent expressions computed from initially known values.
This tips the balance in favour of using rather more complex rational polynomial starting guesses and fewer iterations to get the final answer (ideally just one pass through a higher order NR, Halley, D4 or D5).
Every intermediate answer is a pipeline bottleneck since its value has to crystallise before the next computation that uses it can begin.
BTW any suggestions which journal to publish new numerical algorithms in?
By "doesn't take much" you mean a 70 mph head on crash or being parked next to fossil fuel vehicles that have a predilection for bursting into flames?
The electrolyte is not anything that is of value. The lithium is also not particularly valuable. It is the nickel and cobalt that are getting hard to obtain and seeing large price increases. As battery technology improves, less cobalt will be used. The other materials are more of a supply chain issue than a fundamental limitation in availability. These can be addressed by stepping up production.
No need for zone refining or magic ingredients. When raw materials are obtained from mines, they are in very impure forms, often in hard to break down oxides along with other metals that constitute difficult to separate ingredients. From what I've read, the hard part of recycling batteries is taking them apart to get to the "good" stuff inside.
But the best way to dispose of used BEV batteries is to not dispose of them. Instead recycle them to other uses. A car battery is considered worn out when the capacity drops to 70%. This is a point where the remaining range does not justify lugging around the weight of the battery. However, it is still a very workable battery for stationary devices, such as a home back up system. Even 70 kWh is very adequate in that application and the battery could last another 10 years! So we are still a long way from needing to deal with massive amounts of recycled batteries.
Yes, that is why the charge rate of BEVs is strictly limited by the Battery Management System (BMS) as a function of temperature, state of charge and likely age.
I don't know what "models" you are referring to. Batteries? Cars? I've not heard of any such limitations. You probably got this from the sources that talk about BEV fires while ignoring ICE fires.
??? Can you explain what you are talking about?
I guess there is a reason why Dyson got out of the BEV business. You did know they started to design an electric car, right? I think a lot of people were put off by the attachment storage. Yeah, it had all sorts of wands and hoses. ;) But the car was for real.
Are you in North Dakota or Saskatchewan or maybe Finland? You have to be pretty far north to be colder than Norway where BEVs make up over 80% of new car sales. In the US, there aren't many states that don't have enough Tesla chargers to travel anywhere in the state you want... or at least pass through the state on your way to somewhere else.
Some people enjoy that. Some get sick.
What does "Imagine the effects of...", what does that mean? I think you are an excellent example of my idea there is no actually logical thought. Rather we try to attach our emotions to logical processes, however, ultimately, all decision making is emotional with varying degrees of success in keeping it logical.
It is clear that you know little about the workings of BEVs, yet you postulate all manner of scenarios involving them based on how you perceive their workings.
I was thinking about that, last night, and realized there might be some information to gain as to "where" by examining the sorts of publications I typically consult for *other* "application domains" (that aren't as esoteric as yours).
[I've never really paid attention to the source(s) of these documents as I'm really only interested in their content and just "accumulated" them from <wherever>]E.g., I've reviewed lots of simulations of EV battery performance that might shed insight on where folks interested in that sort of thing go to find it. (I doubt treatises on prosthetic limbs would shed much light! Or, heuristics for HVAC control, etc.) Most typically *not* "EV forums" (or HVAC forums) but, rather, scholastic undertakings which, I assume, is more in line with your audience. Or, are you looking to target something *specific* (like the SETI crowd)?
Example? And the Great Fire of London and the Great Chicago Fire
The battery has to be kept cool with a copious flow of water, which is a pretty conventional firefighting technique. Once the battery has got hot enough to burst the cells and expose electrolyte to air where it can burn, the battery is going to keep on self-discharging until all the stored energy has turned into heat.
Catching the self-discharge at an earlier stage before the battery gets anywhere near that hot, and dragging the car out of the parking lot before it can catch on fire is an approach that would work. Flyguy doesn't understand how this might be done, and certainly isn't going to use what's left of his brain to work out the implications of it being possible.
A gasoline powered car in the same state volatilises the gasoline in the tank, and water can wash that away, which spreads burning gasoline all over the place, so other firefighting techniques are preferred.
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