There was a more detailed account floating around. Essentially, each battery cell is in its own fire-resistant compartment. The fire crew that responded to the call used procedures that are standard for other electric cars, but are not proper for a Tesla. Essentially, they "punched through" these compartments in an attempt to extinguish the fire, which actually exacerbated the problem by allowing the fire to spread to other battery cells.
When the fire department arrived, they observed standard procedure, which was to gain access to the source of the fire by puncturing holes in the top of the battery's protective metal plate and applying water. For the Model S lithium-ion battery, it was correct to apply water (vs. dry chemical extinguisher), but not to puncture the metal firewall, as the newly created holes allowed the flames to then vent upwards into the front trunk section of the Model S. Nonetheless, a combination of water followed by dry chemical extinguisher quickly brought the fire to an end.
Why do you say that? The fire department is a service hired by us to extinguish our stuff. Didn't they learn how to put out gasoline engine car fires 100 years ago? They should have refused because they only knew how to put out horse fires?
In those 100 years, we've learned a thing or two. Which is why we have fire codes and whatnot. We reduce the variation in the number of expected scenarios.
I'll also note that in general, it is easier to learn something different when it's not similar to what you already know. Horse fire vs car fire is easy. Car type A vs car type B vs car type C is more difficult.
Tesla is actually _really_ good at distributing training materials to emergency responders. All vehicle manufacturers do it some some extent, but Tesla sets a very high bar.
Fire departments had to get special training for the Prius (and other hybrid cars) because of the power cabling going from the rear battery to the front. It's not that unusual.
I've never seen a car fire until last week, when I passed by this: http://i.imgur.com/k0xylRe.png. I was really surprised at how large the fire was (it looked worse in person)
Same problem in the WA fire. You cannot extinguish a LiIon fire without (it seems) cutting the car open. In Wa, they put out the fire and it restarted. They had to flip it over and cut holes in it (presumably, through the floor)
The thing to remember with a battery fire is that it's not enough to just put out the flaming electrolyte, when the battery is shorted out you don't just lose all that energy, it gets converted into heat which is what ignites the electrolyte. The battery in a Model S is made up of 11 modules so when one of these modules is shorted you don't have the entire capacity of the battery being turned into heat but depending on if an entire module was shorted out or maybe two adjoining modules that's still a lot of energy and once the whole thing starts burning you might compromise the other batteries in the system.
Tesla engineered firewalls in between the battery modules but it's not like it's fireproof forever, it just means the heat has to transfer through conduction and gives the driver additional time before the vehicle goes up or before the fire department gets there. What might be a good improvement is a 2.5 inch fire hydrant fitting under the back of the car that the fire department could connect to to flood the battery compartment with water and just hook the car up to a hydrant for 30 minutes to make sure the fire stays out.
> Car fires happen regardless of engine technology.
Of course. But nobody has statistics about the rate of fires per accident type.
And remember that this isn't necessarily a reflection on the engine technology but more so the design of the car. Given that accidents often result in debris and also that people drive over stupid things maybe batteries shouldn't be under the cabin floor.
Its pretty rare for car fires to happen on public highways. Most car fires are incidents with a vehicle at rest, or deliberately set. Something like 2% of accidents involve petrol based fuels systems. Many more are cuased by other issues.
Telsla (as an example) previously recalled ~40% of its Roadster models in 2010 for fire-hazard related faulty wiring. That kind of thing would be attributable to any type of car.
The high incidence of Model S LiIon fires in the field, is much more problematic and worrisome, IMHO. Like you say, it may just be a design flaw on the location of the battery pack. Aft of the front axle is a debri-zone, wheras aft of the rear axle would be more protected from debris (but subject to crumple zone impacts compromizing the integrity of the pack directly or through shrapnel)
The problem with tesla is the active suspension dropping you to a couple inches off the road on the highway. Debris that you would normally pass over shoots into the under carraige..
This is a really helpful and pertinent insight IMO.
A few solutions:
Turn off dynamic highway suspension feature
Use RADAR to detect debris and cause suspension to lift to avoid as much damage (could cause vehicle instability)
>To avoid instability, slowly lift suspension, slow down lift towards apex, lift front suspension first and then rear suspension, and/or slow the vehicle slightly before raising suspension. (Could use rear-facing RADAR to inform decision process about slowing down.)
Of course, with more automation and sensors, the car could possibly change lanes autonomously to avoid road debris all together. (and message the highway patrol and other automated or semi-automated vehicles of the location of the debris as warning)
One last solution I can think of is to somehow either strengthen the undercarriage or add deflectors or crumple zones of some kind.
Personally, I'm thinking that better accident avoidance automation will be the most reliable...including raising the clearance. And making the batteries more puncture-resistant would be great.
On a tangent, would it reduce the likelihood of combustion of the batteries if each compartment could recognize a puncture event and quit drawing power from the batteries in that compartment?
I'm waiting for the day that fully autonomous vehicles are legal and affordable. In the meantime, semi-automous vehicles that "... message the highway patrol and other automated or semi-automated vehicles of the location of the debris as warning ..." is an awesome use of a sub-set of the autonomous technology, and a great way to demonstrate such vehicles' capabilities!
By apex I presume you're saying that as the suspension finishes lifting the car, the act of effectively "throwing" the car up into the air will momentarily lower the apparent sprung weight. Makes sense.
If the suspension can act very suddenly, it could execute only when collision is unavoidably imminent.
When the fire department arrived, they observed standard procedure, which was to gain access to the source of the fire by puncturing holes in the top of the battery's protective metal plate and applying water. For the Model S lithium-ion battery, it was correct to apply water (vs. dry chemical extinguisher), but not to puncture the metal firewall, as the newly created holes allowed the flames to then vent upwards into the front trunk section of the Model S. Nonetheless, a combination of water followed by dry chemical extinguisher quickly brought the fire to an end.
http://www.teslamotors.com/blog/model-s-fire
I saw a Nissan in fire a month or so ago outside of Philly. Car fires happen regardless of engine technology.