I'm just explaining the viewpoint of the letter since you were unsure. I'm not opining that it is effective/ineffective or productive/counterproductive.
I think the point is still valid that the safety features are nice but the core issue is that the car burst into flames during a seemingly minor accident.
...or maybe not. You're just speculating.
I've run over stuff at high speeds in other cars, and I"m here to tell you that they didn't flip over, puncture, or burst into flames. The most common outcome, in my experience, is that the oil pan or transmission pan gets dented, and starts to leak.
I'm fairly impressed with Tesla's record so far, but mounting a half ton (literally) of energy storage to the entire underside does raise some interesting questions.
To really understand where the Tesla ranks in safety, we would need a detailed analysis of: the accident, how non-Tesla cars handled similar accidents, how the Tesla is designed to handle such an accident.
I do agree that we have no where near enough data to draw general conclusions about the safety of the Teslas, so I think it's inappropriate to say, "they are doing better[or worse] than the average."
I think this is precisely the idea they are combating. The initial news reports didn't have any details and just said there was Tesla on fire on the side of the highway.
Once the numbers of cars become large enough we can simply look at the outcome numbers, to determine how likely that outcome is. It doesn't matter if a car is "designed to handle such an accident". What matters is if it does handle a given kind of accident.
A Tesla car is unlikely to ever be involved in a fire at a gasoline station. We probably shouldn't give combustion vehicles a free pass there.
As more and more Tesla cars hit the road, confidence level increases in the stats that are derived. Early data is not meaningless; it can be indicative of later results.
Low probability events happen all the time, and I don't think we can draw any solid conclusions from these anecdotes (other than driving any vehicle is potentially dangerous).
Hah! I love how extremely counter-intuitive and completely true this sentence is at the same time.
It really depends on what kind stuff the car runs over and how fast the car is moving, and also how well the driver is handling the situation when it happens. I've almost run over ladders and mattresses, but never trailer hitch. Maybe I'm lucky.
Once I had a rock the size of a golf ball smack into my windshield on the highway. It hit with such force that it made a noise that almost sounded like a gunshot, it was quite startling. It didn't leave even the smallest mark on the windshield though. Another time a tiny pebble the size of a pea hit my windshield and made a very sizeable chip in it.
Anecodtes involve luck (good and bad), the purpose of statistical analysis is to gather enough data so that the luck, which should be random, is filtered out from the "signal".
But in no way was it a major accident.
Driving over something at highway cruising speed doesn't seem all that major to me.
It's major enough that, as other commenters have noted, it would rip apart the undercarriage of any smaller car, and possibly enter the cabin through the floor.
Vhulls are only useful for upwards blasts...short of IEDs showing up in California the concept is useless for a sportcar. Also...humvee doesn't have a vhull - prototypes aside. You're likely thinking of either the MRAP or some buffalo derivative.
Pretty much every other area will suffer too - handling, aesthetics, fuel efficiency, manufacturing complexity, battery replacement etc.
Its just a horrible trade-off.
But so what ? It would never start a fire.
I've personally seen more than 1 regular gasoline car catch fire for various reasons.
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.
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)
If the suspension can act very suddenly, it could execute only when collision is unavoidably imminent.
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?
What planet are you on?
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.
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.
As an example, check out this training video they put together: http://www.youtube.com/watch?v=ntK3rvVl2Qw (skip to 26:45 for the fun part ;)
This video in particular is about extrication, not firefighting, but you get the idea...
We train frequently to deal with the new challenges presented by electric vehicles.
the point is that the car knew it was damaged and self diagnosed properly, and that electric circuits are all properly isolated and monitored. Pretty cool if you ask me.