Tesla on fire: not good.

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Discussion

Helicopter123

Original Poster:

8,831 posts

155 months

Sunday 17th June 2018
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Max_Torque said:
Helicopter, i see you drive a porsche Cayenne (nice car btw), guess what, they catch on fire "randomly"





oh dear oh dear, clearly "unacceptable" so i guess you're selling yours tomorrow yeah?


This is my point, NOTHING is 100% reliable. We accept a level of risk of any event, based on the probability of it occurring and the possible damage that might result if it were to occur. You Cayenne can catch fire, due to a fault, or an accident , but you have made a very sensible decision to drive it, as the risk you feel to yourself is not significant.

And, statistics show, EV's are, as i've said 3 or 4 times now, LESS likely to suffer a fire (due to either an accident or a fault) than an ICE powered vehicle.

So, if you drive your Cayenne, then there is no reason not to drive an EV.......
So petty...

But then I see you have an i3 - weren't they subject to a specific product recall due to fire hazard?


Blaster72

10,771 posts

196 months

Sunday 17th June 2018
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For someone who sits on the industry safety board, you haven't really offered any insight into what improvements are or could be made. Merely stated you're happy as they burn less often that legacy vehicles.

Not a particularly comforting thought that someone in your position takes this kind of slack attitude to safety.

Blaster72

10,771 posts

196 months

Sunday 17th June 2018
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Moving on Max, seeing as you have the stats. Are the Zoe and Leaf much better than Tesla? I don't see as many of those bursting into flames.

Helicopter123

Original Poster:

8,831 posts

155 months

Sunday 17th June 2018
quotequote all
Helicopter123 said:
Max_Torque said:
Helicopter, i see you drive a porsche Cayenne (nice car btw), guess what, they catch on fire "randomly"





oh dear oh dear, clearly "unacceptable" so i guess you're selling yours tomorrow yeah?


This is my point, NOTHING is 100% reliable. We accept a level of risk of any event, based on the probability of it occurring and the possible damage that might result if it were to occur. You Cayenne can catch fire, due to a fault, or an accident , but you have made a very sensible decision to drive it, as the risk you feel to yourself is not significant.

And, statistics show, EV's are, as i've said 3 or 4 times now, LESS likely to suffer a fire (due to either an accident or a fault) than an ICE powered vehicle.

So, if you drive your Cayenne, then there is no reason not to drive an EV.......
So petty...

But then I see you have an i3 - weren't they subject to a specific product recall due to fire hazard?
https://insideevs.com/bmw-i3-rex-recalled-for-fire-risk-thanks-to-its-gas-extender/

Here you go.

They really shouldn't be allowed to sell ANY car until it's safe.

Using the general public to do your safety testing is not acceptable, regardless of the power source.

essayer

9,008 posts

193 months

Sunday 17th June 2018
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The official advice when a ZOE battery catches fire is to remove the rear bench and spray water into the traction battery vent that’s underneath.
eek
Guess all EVs are similar..

Source: http://www.elbilsinfo.se/storage/cms/4b7986b575724...

Edited by essayer on Sunday 17th June 18:16

anonymous-user

53 months

Sunday 17th June 2018
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dvs_dave said:
Petrol/Diesel car crashes and catches fire, rapidly burns and explodes. People injured/killed. No one cares, happens all the time, doesn’t even make it beyond a local news sidebar. Tragic, shame blah blah.

Electric car crashes, catches fire, and slowly burns. No one injured. Makes world news and the great unwashed thinks they’re dangerous and no amount of hard facts to the contrary will dissuade them from their parochial Luddite opinions.
For the sake of fairness i should mention that an ICE fuel tank actually exploding is very rare, because they are designed to vent in a controlled fashion. There is a "fuel tank fire" test that all cars homologated in the EU must pass, that involves basically shoving a large tray full of buring kerosene under the back of a car, right under the fuel tank, retiring to a safe distance and seeing what happens. The test can be failed by two major factors 1) the tank being compromised too quickly (limit is >3min iirc) and the tank "exploding" or venting producing a pressure wave (can't remember the limits off the top of my head)

What isn't rare is ICE fires due to hot exhausts setting fire to flamable materials (usually dry grass) which is the no1 cause of car fires these days, and one of the reasons an EV is so muchless likely to experience a fire (because it doesn't have a hot exhaust / catalyst)

Also common, are electrical fires due to shorted looms and again because EVs have more modern electronics they are much more likely to include better overcurrent protection and hence less likely for a short to result in a fire

Finally, Brake fluid is actually the no1 cause of ICE fires after accidents, as unlike petrol, which just flashes straight to vapour without igniting on contact with say a hot exhaust manifold, the lower vapour point and volatility of brake fluid results in a fluid fire in a large number of cases.


Often ICE cars that catch on fire can result in a large spreading fire, because once the tank is compromised (and it always is eventually in a full vehicle fire) the liquid fuel runs out, and away from the car , on fire. Multistory car parks are very susceptible, with fire even spreading down a level or two as the vehicles release there fuel..


Helicopter123

Original Poster:

8,831 posts

155 months

Sunday 17th June 2018
quotequote all
essayer said:
The official advice when a ZOE battery catches fire is to remove the rear bench and spray water into the traction battery vent that’s underneath.
eek
Guess all EVs are similar..
Christ, it's such a common thing they have 'official advice' on it?

yikes

youngsyr

14,681 posts

191 months

Sunday 17th June 2018
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Max_Torque said:
car_fires_gov_statistics

approx 15,000 accidental (ie not set on fire deliberately/arson) car fires in the Uk per year, that's 43 per day!
That statistic on one level doesn't surprise me: I've seen several cars burning by the roadside recently.

On the other hand, those cars were relatively new models, so I am surprised that modern cars are still seemingly a reasonably high fire risk.

Assuming there are roughly 30m cars on the road, that's roughly 1 in 2,000 catching fire per year. Again, assuming a 10 year life span, that's a 1 in 200 chance of your car catching fire in its lifetime.

anonymous-user

53 months

Sunday 17th June 2018
quotequote all
Helicopter123 said:
Helicopter123 said:
Max_Torque said:
Helicopter, i see you drive a porsche Cayenne (nice car btw), guess what, they catch on fire "randomly"





oh dear oh dear, clearly "unacceptable" so i guess you're selling yours tomorrow yeah?


This is my point, NOTHING is 100% reliable. We accept a level of risk of any event, based on the probability of it occurring and the possible damage that might result if it were to occur. You Cayenne can catch fire, due to a fault, or an accident , but you have made a very sensible decision to drive it, as the risk you feel to yourself is not significant.

And, statistics show, EV's are, as i've said 3 or 4 times now, LESS likely to suffer a fire (due to either an accident or a fault) than an ICE powered vehicle.

So, if you drive your Cayenne, then there is no reason not to drive an EV.......
So petty...

But then I see you have an i3 - weren't they subject to a specific product recall due to fire hazard?
https://insideevs.com/bmw-i3-rex-recalled-for-fire-risk-thanks-to-its-gas-extender/

Here you go.

They really shouldn't be allowed to sell ANY car until it's safe.

Using the general public to do your safety testing is not acceptable, regardless of the power source.
did you use use a fire resulting from the ICE bit of a range extended EV to argue that EV's are not fire resistant enough?? ;-)

and define "safe". this is the point i'm trying to make, nothing can ever been 100% safe, it's all about probability and risk.

Blaster72

10,771 posts

196 months

Sunday 17th June 2018
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To be fair to Max, I'm thinking in the future the bigger threat will be shonky house wiring going up in smoke when daughter, son, mum and dad all have their cars on the charge using an extension lead.

As much as I probe a bit whenever there is a blaze, Tesla have done an ace job so far with the tech they have at present and things really can only get better.


anonymous-user

53 months

Sunday 17th June 2018
quotequote all
Blaster72 said:
For someone who sits on the industry safety board, you haven't really offered any insight into what improvements are or could be made. Merely stated you're happy as they burn less often that legacy vehicles.

.
Er, you didn't ask me to explain what safety improvements could be made, as you were too busy telling me that EVs are too dangerous, despite them being safer than ICEs

If you'd like me to explain some of the mitigation techniques for large scale, high density batteries in EVs then sure i can do that?
(but i should say, none of the methods that can bring significant extra safety are actually practicable, or cost effective, or they would have been done already)

Blaster72

10,771 posts

196 months

Sunday 17th June 2018
quotequote all
I am interested in hearing thanks, in aviation we very recently had two very significant battery fires on a new model.

Both had different causes and different "fixes" but at no point did anyone try to defend the model by deflecting onto other previous aircraft types.

Surely Tesla take these in isolation and use the findings to learn and improve, I understand their PR machine is probably seperate from engineering and they feel they have to go on the defence.

Other than saying it looked a bit tricky getting out without burning legs, I don't think I've used this thread to peddle any Teslas are dangerous agenda. I just get fed up with Tesla fanatics trying to shut down every conversation that involves hearing something they don't like about their Church/Cult.

In your opinion, are Teslas somehow burning up more often than other EV's like the Leaf or Zoe?

anonymous-user

53 months

Sunday 17th June 2018
quotequote all
Blaster72 said:
Moving on Max, seeing as you have the stats. Are the Zoe and Leaf much better than Tesla? I don't see as many of those bursting into flames.
Both the Zoe and LEAF use automotive rated "Pouch" cells, whereas Tesla, use cylindrical "laptop" 18650 cells. Those small round metal cells can be more susceptible to fire after piercing (due to complicated geometrical factors i won't go into here). Note i said "can" and not "are". Zoe and Leaf also have much smaller batteries, meaning less chance overall of experiencing a faulty cell (say 0.0001% of cells are faulty, then a car using 1000 of them is twice as likely to experience a faulty one than a car using 500 of them). And of course, Zoe and Leaf are much lower performance cars, meaning the cells are not stressed as much as in a Tesla.

I don't have enough data to be able to tell you if a Zoe is less likely to experience a battery fire than a Tesla, but lab testing at a cell level suggests that 18650 cells are more likely to experience a thermal event than specific automotive pouch cells.

anonymous-user

53 months

Sunday 17th June 2018
quotequote all
Blaster72 said:
I am interested in hearing thanks, in aviation we very recently had two very significant battery fires on a new model.

Both had different causes and different "fixes" but at no point did anyone try to defend the model by deflecting onto other previous aircraft types.
As i'm sure you are aware, overall risk is Probability x Result, and hence you cannot compare a single aircraft fire which potentially could kill everyone on the plane and hundreds more on the ground with an EV car fire, that (and i'm not 100% sure of this) as far as i know has not killed anyone yet?

Because EV fires are slow burning they are not classed as "high risk" in the industry. It's worth noting that the heat release from the rest of the car burning, is roughly 100x more than the heat release for the 100KWh battery burning, ie once the car is on fire, the battery bit is actually not that important (also worth noting, that injuries as a result of car fires are mostly due to tyres exploding off the rims and hitting the fire crews trying to put them out, so if you ever approach a burning car, do so from the front or back (where the wheel arch gives a level of ballistic protection) and not the side !

The Automotive industry is working hard to totally eradicate EV battery fires, and several battery chemistry improvements are already helping, but it's un-realistic to expect zero fires, so the current industry state is effectively "Safer than ICEs" and "minimise injury" both of which a modern EV already meets.

Blaster72

10,771 posts

196 months

Sunday 17th June 2018
quotequote all
Thanks for all the info, I've just had a little read of this as well which says they're moving to a different battery for the later model year cars and the Model 3.

https://www.maximintegrated.com/en/design/blog/tes...

I suppose the biggest threat to the battery is damage which causes thermal runaway. Tesla try to stop this with re-inforcement and some amount of comparmentalising but it doesn't seem to be enough.

I remember when the Model S was launched they had to update the air suspension software to run a bit higher at motorway speeds than originally as people were clobbering road debris and damaging the batteries.

It's a tough problem to solve, particularly when the cars get older, cheaper and generally a little less well looked after.

At the moment, I'd happily park my car in the garage under my house. I'd be a little reluctant to do the same with any EV on charge. Despite the stats showing how safe they as daft as it sounds.

anonymous-user

53 months

Sunday 17th June 2018
quotequote all
Blaster72 said:
I suppose the biggest threat to the battery is damage which causes thermal runaway. Tesla try to stop this with re-inforcement and some amount of comparmentalising but it doesn't seem to be enough.
The problem is where do you stop? It's technologically possible to build today a passenger car that would enable it's occupants to withstand ANY accident. But it would look like a Challenger tank, and cost £1M, so we don't. We accept a level of risk against the pragmatic values of cost effectiveness and of course aesthetics.

The best way to prevent thermal damage is to stop the car (or battery or whatever) catching fire in the first place, and for EVs it's really early days yet. There simply isn't the necessary number of fires occurring for us to put together a statistically valid picture. The data is, as i have mentioned, hugely skewed by Rest Of World (RoW) fire data, where something riduclous like 85% of passenger car fires are a result of parking a hot car on hot, dry grass or scrubland. In the Uk, thanks to our rain, that is an unusual event (it can happen and has done so, with car park fires breaking out at outdoor music events where people have been parked in grass fields). So, EV's, not being susceptible to the dry grass ignition fire, would, over night, cut car fires by 85% immediately!.

Once away from hot parts of cars igniting the countryside type fires, then generally, in the EU, it's an 12v electrical short that is the most common cause of a fire (if we exclude fires resulting from accident damage, where brake fluid on hot exhausts is no1 fire starter). if you look at the .gov statistics i posted earlier, car fires have fallen by around 40% in the last 15 years, despite the number of cars on our roads going up by about 11%. There are two main drivers behind this (significant) fall:

1) more diesels (it's much less likely to ignite if it leaks out) and colder exhaustline components

2) Better fusing and electrical systems (cars since around the early 2000's have things like pyrotechnic battery fuses and semiconductor over-current protection, and the move to high speed serial databus architectures (instead of individually hard wiring everything) has reduced loom complexity (and hence susceptibility to failure)

But on the flip side, increased electrical and mechanical complexity, and a much greater packing density have lead to more systematic thermal events. For most volume built cars, the robust product development cycle mitigates against thermal events to a large degree, where failures during development lead to design changes for production, but some low volume, and in particular, high performance cars can be er, highly, inflamable (the typical Ferrari or Lambo goes though a much less rigorous development process (in terms of statistical robustness, ie miles driven across a fleet of test vehicles) and often is much more tightly packaged and produces a lot of heat (6.5l V12 anyone?)


Companies like Tesla are still investigating where the sweet spot lies, and that takes time, an unfortunately, real world accidents. I don't have the figures to hand, but i'm don't think many (any??) people have been killed in a Tesla crash that didn't die from the impact itself. In the well published case a few years ago, the owner hit a tree at what the airbag computer logged as ~110mph, effectively reduced his car, and himself unfortunately to component parts, and yes, parts of the battery did ignite and smolder for a bit. For the driver, killed in the impact, i guess that really didn't make any odds?



anonymous-user

53 months

Sunday 17th June 2018
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Regarding fire mitigation for EVs the following has been tried and ruled out:

1) Water suppression. The amount of water necessary is impossible to package into a passenger car. (mass and volume) and injecting water into a HV battery carries it's own safety risks (much more likely to die from an invisible to a human HV electrical shock than a burning fire, from which most sensible people run as fast as their legs will carry them)

2) Cryogenic suppression: Fraught with dangers that heavily outweigh the benefits. Carrying 100 or more litres of cryogenic fluid at high pressure or at ultra low temperature is going to cause more issues than it solves. This technique is used successfully for development battery testing in fixed battery test chambers, but is impractical and potentially lethal (pressure vessel bursting, ultra cold injuries, asphyxiation etc etc) in a car

3) Battery ejection: Again, has been used for battery testing where there is ensured to be somewhere safe to eject the burning battery too, but a non starter for a car, which could be anywhere when a fire starts! (You'd be pretty miffed to be chased down the ramp in a multistory car park by a burning EV battery ejected from a car on the next level eh....... ;-)

3) Mechanical / Thermal restraint: Really this is the only one that is possible. You cannot seal the battery otherwise it becomes a high pressure bomb, so you have to allow it to vent. The best solution so far, but one that no customer would accept, is to fit each EV with an insulated chimney sticking out the roof. If the battery catches fire, it's retaining in it's (expensive and heavy) fire proof enclosure, and the smoke and flames are simply vented up and out of the roof.

The biggest issue is aesthetics, most people don't want their shiny new car to look like this:



But also issues when cars are in garages, or other internal or built up areas etc



No, by far the best option is to stop the battery catching on fire in the first place!

Blaster72

10,771 posts

196 months

Sunday 17th June 2018
quotequote all
I'd have thought most car fires were caused by accidents rather than grass fires. Catalytic convertors have good shielding now to stop long grass from igniting and they cool down really quickly.

Putting that aside, Tesla have address the protection somewhat in the Model S. Initially the battery protection was poor and easily punctured, this was redesigned with a 3 stage protection (and ride height changes as mentioned above).

The have fixed their battery tech for the foreseeable future so I guess need to keep reviewing and if possible improving on the protection system to reduce the number of fires to as low as possible.

For the one that started this thread, the owner insists the car hasn't been in an accident so it'll be interesting to see if in fact the battery was punctured without him noticing by road debris, kerb hopping etc... I'd be surprised if he'd hit anything hard enough to damage the battery without noticing though. Maybe Tesla will also view the footage and work on routing any battery fumes/ flames away from the door exits (to the rear for example?).

GT119

6,333 posts

171 months

Monday 18th June 2018
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Why is there mass hysteria when a Tesla catches fire and no-one was injured.
ICE cars catch fire all the time, especially when wrapped around a tree (RIP Paul Walker).
Looking at the Reuters article the only people who died either drove off a cliff, drove through a concrete wall or wrapped the car around a tree.
So it would appear that as long as you don't steal them and/or drive them like you stole it (or fall asleep with the autopilot on) you aren't going to die.

A common lawyer

319 posts

127 months

Monday 18th June 2018
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I'm not a regular poster, but I do lurk a bit, and I just wanted to thank Max Torque for the really rather informative posts. It's fascinating to see where the industry is headed, and you always seem to be able to explain relatively complex things so that even I can understand. Keep up the good work!

Cheers.