BEV battery fires.

[edatoakrun]

It is obvious every BEV occupant will be far safer from fire than any liquid-fueled ICEV/PHEV, under the vast majority of circumstances.

I'm just wondering how to answer the inevitable "battery fire" hazard question, RE the LEAF.

As to the LEAF (AFAIK) there have been no battery fires due to either collisions or from other sources of ignition.

...Several plug-in electric vehicle fire incidents have taken place since the introduction of mass-production plug-in electric vehicles in 2010. Most of them have been thermal runaway incidents related to the lithium-ion batteries and have involved the Zotye M300 EV, Chevrolet Volt, Fisker Karma, BYD e6, Dodge Ram 1500 Plug-in Hybrid, Toyota Prius Plug-in Hybrid, Mitsubishi i-MiEV and Outlander P-HEV, and Tesla Model S. As of October 2013, two fires after a crash have been reported associated with the batteries of plug-in electric cars. The first modern crash related fire was reported in China in May 2012, after a high-speed car crashed into a BYD e6 taxi in Shenzhen.[155] The second reported incident occurred in the United States in October 2013, when a Tesla Model S caught fire after the electric car hit metal debris on a highway in Kent, Washington state, which punctured one of 16 modules within the battery pack.[156][157...

http://en.wikipedia.org/wiki/Plug-in_electric_vehicle#Risks_of_battery_fire" onclick="window.open(this.href);return false;

Is the LEAF battery pack design so resistant to thermal runaway that battery fires are near-impossible, or just very unlikely?

As to the Tesla S battery fire, has there been a definitive report of whether the fire was a result of direct damage to the battery cells (puncture or deformation?) and an internal short, or from damage to the ATM cooling system, from the road debris?

Musk's statement is more vague than the wikipedia entry above:

http://www.teslamotors.com/blog/model-s-fire" onclick="window.open(this.href);return false;

Those following the ~95 pages here, may know the answer.

http://www.teslamotorsclub.com/showthread.php/22173-Model-S-Accident-Fire" onclick="window.open(this.href);return false;

 

[Nubo]

LEAF choices result in a battery system that is more inherently stable. The critical temp is that at which the battery starts producing oxygen, and that is much higher for the LEAF chemistry. Also, keeping water away from the cells is a safety plus, imo.

Inherently stable vs. actively stabilized....?

Of course, any energy storage system has inherent risks if the energy is released all at once. And this is not to say that Tesla isn't adequately managing those risks. But some of the Tesla risks are managed instead of avoided, because they want to take advantage of the greater energy density of the Lithium-Cobalt chemistry.

Ideally you want Tesla-like range from a LEAF-like chemistry that doesn't require active cooling. Some day. In the meantime if it's safer than gasoline, the issue is kind of a nit, aside from those who would twist any event to put the new tech into a bad light.

 

[edatoakrun]

="Nubo"]LEAF choices result in a battery system that is more inherently stable. The critical temp is that at which the battery starts producing oxygen, and that is much higher for the LEAF chemistry...

Yes, I understand.

What I don't know, is if there any plausible combination of initial temperature and battery damage from a collision that could cause a thermal runaway event in a LEAF battery pack, posing a safety hazard to the vehicle passengers?

 

[Nubo]

LEAF choices result in a battery system that is more inherently stable. The critical temp is that at which the battery starts producing oxygen, and that is much higher for the LEAF chemistry...

Yes, I understand.

What I don't know, is if there any plausible combination of initial temperature and battery damage from a collision that could cause a thermal runaway event in a LEAF battery pack, posing a safety hazard to the vehicle passengers?

The LEAF cells will still go into thermal runaway given enough heat. Short enough cells and you can provide plenty of heat. How plausible such a scenario would be in an otherwise-survivable impact, I can't say.

 

[DanCar]

http://www.forbes.com/sites/jimhenry/2011/12/22/nissan-says-batteries-for-the-nissan-leaf-can-take-a-licking/" onclick="window.open(this.href);return false;
Around 20 units of the Nissan Leaf were damaged in the March earthquake and tsunami in Japan, a Nissan spokesman said. Some were utterly “crushed and mangled,” and some had seawater damage, but no battery fires resulted, the company said.

 

[gbarry42]

It would be an interesting test to short circuit one module of the LEAF battery and see what happens. (Do not try this at home. Just sayin')

 

[gbarry42]

Also: As an answer to the general case of "how to respond to any BEV fire", I found this priceless entry ( http://www.teslamotorsclub.com/show...Friends-Relatives-Who-Bring-Up-The-Tesla-Fire ) on the Tesla Motors forum. I want to give credit to the poster, jackbowers. This is one of those "Discussion.Over." kind of posting. I've repeated it in its entirety.

How To Handle Friends/Relatives Who Bring Up The Tesla Fire

Whip out your smart phone and search the Make/Model of the car they drive followed by the words "on fire." Some 90% of the time you'll find some pretty nice video to show them. This drives home the point that car fires are not uncommon, and that they are usually worse when gasoline is on board.

 

[DanCar]

It would be an interesting test to short circuit one module of the LEAF battery and see what happens. (Do not try this at home. Just sayin')

I'm sure Nissan has done this. Would be nice to see video of puncture test. Should be a tad borish.

 

[edatoakrun]

LEAF choices result in a battery system that is more inherently stable. The critical temp is that at which the battery starts producing oxygen, and that is much higher for the LEAF chemistry...

Yes, I understand.

What I don't know, is if there any plausible combination of initial temperature and battery damage from a collision that could cause a thermal runaway event in a LEAF battery pack, posing a safety hazard to the vehicle passengers?

The LEAF cells will still go into thermal runaway given enough heat. Short enough cells and you can provide plenty of heat. How plausible such a scenario would be in an otherwise-survivable impact, I can't say.

Others have suggested that the LEAF battery design is (virtually?) fireproof.

No idea if this is correct, or whether the complete absence (?) of reported battery fires in the ~85 k LEAFs driven hundreds of millions of miles is just a statistical anomaly.

A not-very-reliable-source (IMO) reported that even a fire that consumed a LEAF completely would not lead to a LEAF battery fire:

A Seriously Burned Out Nissan LEAF

...This is strictly associated burn damage from a fire in Colorado. If there is any takeaway from this fire, it is that the battery pack did NOT catch fire, and remarkably remains structurally intact, tucked beneath the car

.

http://insideevs.com/a-seriously-burned-out-nissan-leaf/" onclick="window.open(this.href);return false;

The latest video of a Tesla S battery fire is considerably more dramatic than the one from a few weeks back, IMO.

http://insideevs.com/video-tesla-model-s-in-flames-after-violent-crash-in-mexico/" onclick="window.open(this.href);return false;

 

[ObiQuiet]

This drives home the point that car fires are not uncommon, and that they are usually worse when gasoline is on board.

Even Musk's pithy statement "there should be absolutely zero doubt that it is safer to power a car with a battery than a large tank of highly flammable liquid" is pretty compelling.

 

[smkettner]

Don't forget the Tesla warned the driver of malfunction so that he could stop and evacuate. Not sure if LEAF has similar warning.

Gasoline vehicle of course has the black smoke and yellow flames as the warning :shock:

 

[RegGuheert]

The latest video of a Tesla S battery fire is considerably more dramatic than the one from a few weeks back, IMO.

http://insideevs.com/video-tesla-model-s-in-flames-after-violent-crash-in-mexico/" onclick="window.open(this.href);return false;

+1

That explosion appeared quite powerful! Was that a single cell going up?

 

[palmermd]

Any vehicle going fast enough to go up over the small wall, crash and take out the large wall that has an electrical service mounted to it and then cross the road and crash into a tree would probably be pretty well done. Amazing that the driver got out unhurt and is thankful he was in a Tesla and is reportedly excited about purchasing one again to replace the one he damaged.

image taken from TeslaMotorsClub.com
http://www.teslamotorsclub.com/show...Merida-Mexico)?p=479756&viewfull=1#post479756

 

[edatoakrun]

Any vehicle going fast enough to go up over the small wall, crash and take out the large wall that has an electrical service mounted to it and then cross the road and crash into a tree would probably be pretty well done. Amazing that the driver got out unhurt and is thankful he was in a Tesla and is reportedly excited about purchasing one again to replace the one he damaged...

I hope that Tesla was so kind as to rely that information to local law enforcement...


google translation

...According to witnesses, the driver was traveling under the influences of alcohol and apparently injured.

According to the data, the mishap occurred on Avenue Chamber of Commerce 32nd Street San Antonio colony Cucul, right in the roundabout Pocito.

The Tesla plates 89-73 ZAN-journeyed from west to east on the avenue.

At the roundabout, due to excessive speed, guiding the wheel lost control and crashed into the lining of the gazebo.

The vehicle bounced, jumped the curb and crashed into the site 248, owned by Ligia Marrufo; demolished a part of the electrified fence and then crashed into a tree. On impact, the vehicle caught fire.

With the help of other drivers, the guider out of the car and boarded a private vehicle in which he fled.

A few minutes later came ambulance, police and firefighters SSP. It closed the road to avoid other accidents, and retired to the neighbors, it was feared that there was an explosion.

The flames completely consumed Tesla, which was later removed from the site. The aim is to locate the owner of the car by the plates, to answer for the damages.

http://yucatan.com.mx/merida/choca-varias-veces-e-incendia-su-auto" onclick="window.open(this.href);return false;

 

[Nubo]

Tesla may be the safest car, but the fact remains that the cells they use are fairly easy to provoke into thermal runaway. Now, they have gone to great lengths to engineer safeguards and preventive measures to contain that risk. Probably more thoroughly than any engineering that goes into gasoline cars to contain the risk of the explosively flammable liquid those cars must haul.

Nevertheless, the public will latch on to stories of battery fires. Yes, because of a certain element that resists and fights the changes that, in their fevered imagination are designed to take away their freedom and money. But also because the public is familiar with widely-publicized lithium battery fires in numerous consumer devices. One can explain the safety features meant to contain that problem. But, it's still a problem. And even though gasoline is terribly dangerous, we've had a hundred years to grow complacent and used to that particular danger.

Tesla is walking a fine line in several areas. I do like Nissan's approach in a number of ways even though it currently doesn't yield a long-range car.

I hope to see a convergence within a few years. Some sort of cultural exchange program between the two companies.

 

[GRA]

Tesla may be the safest car, but the fact remains that the cells they use are fairly easy to provoke into thermal runaway. Now, they have gone to great lengths to engineer safeguards and preventive measures to contain that risk. Probably more thoroughly than any engineering that goes into gasoline cars to contain the risk of the explosively flammable liquid those cars must haul.

Nevertheless, the public will latch on to stories of battery fires. Yes, because of a certain element that resists and fights the changes that, in their fevered imagination are designed to take away their freedom and money. But also because the public is familiar with widely-publicized lithium battery fires in numerous consumer devices.

I think Elon's arrogance may come back to haunt him here. After all he was out front and center saying how badly designed the 787's battery pack was, and offering to 'help' Boeing.

 

[DanCar]

There are relatively simple things that Tesla can do to increase safety, although they take time to implement. It can increase the space between cells and increase the fire retardant material in between cells. Can be done on the 60kWh battery pack but will require more engineering for their 85kWh battery pack to create the increased space needed.

 

[edatoakrun]

To goo or not to goo, that is the question...

Simplifying a cheap cell

...for the Model S, Tesla redesigned what was already a relatively simple cell to be much less complex, and to have a much lower manufacturing cost--largely by removing expensive safety systems built into each individual cell.

When used as a laptop battery, each cells requires a safety mechanisms to prevent fires. But in a large, electronically-controlled, liquid-cooled battery pack like the one used in the Tesla Model S, having certain safety features on each cell would be redundant.

In this case, the company's cell design eliminates the relatively complicated battery cap of the commercial cell, and replaces it with a simple aluminum disk.

Intumescent goo

Having radically simplified the cells, Tesla then designed simple and inexpensive fireproofing systems into its battery pack. Among many innovations, Tesla appears to have incorporated a form of intumescent goo that it sprays onto the interior of the pack to aid in fireproofing.

When exposed to heat, a chemical reaction occurs in the goo that helps cool the heat source, while simultaneously forming a fireproof barrier to protect the rest of the pack.

In testing by Tesla, this material often cooled cells experiencing a runaway reaction--to the point that many failed to ignite at all--and provided a fireproof barrier surrounding those that ignited...

http://www.greencarreports.com/news/1084682_what-goes-into-a-tesla-model-s-battery--and-what-it-may-cost" onclick="window.open(this.href);return false;

Those pictures are the ones I took. I can assure you there is no "goo" sprayed on anything except for the conformal coating on the BMS PCB's on the end of each module. The 18650's themselves are bare shiny metal, with about 25% of each cell in contact with a thermal pad. The stuff that looks like goo is simply the thin crinkled kapton polyimide tape (an insulator), and/or the adhesive used to keep the thermal pads in place. I saw zero evidence of any Intumescent material.

-Phil

(and in a later post)

...I don't think Tesla needs the intumescent in this application because the liquid cooling system will conduct enough heat away from a cell to keep it well out of any thermal runaway zone, thus avoiding any thermal events that could lead to a fire.

-Phil

http://www.teslamotorsclub.com/showthread.php/17456-Amazing-Core-Tesla-Battery-IP-18650-Cell/page7" onclick="window.open(this.href);return false;

The significant question I still have about both Tesla S fires, is if they both resulted from collision damage to the cells, or did the loss of coolant alone lead to thermal runaway, and the fire(s)?

Since cooling system failure could be a fairly common problem, particularly as the S fleet ages, I would find the latter possibility somewhat concerning.

 

[ebill3]

Nevertheless, the public will latch on to stories of battery fires.

Boy, isn't that the truth.

Today I was at a shop loading some wine in the Tesla, and a passerby commented on the beautiful car. Of course, the inevitable question: "What is it?" When I told him, his response was: "Oh, like the one that burned up in Seattle." (actually, it was Kent WA)

Sigh

 

[bowthom]

It would be an interesting test to short circuit one module of the LEAF battery and see what happens. (Do not try this at home. Just sayin')

I remember seeing rods driven through leaf modules as a puncture / short test and nothing happened. no fire, no smoke and no arching. I cant find the video now.