Saturday, November 9, 2013

Another Tesla Fire

Once again, road debris has caused a Tesla S to burn. The fact that this happened just down the street from the US LEAF plant and battery factory near Smyrna, TN is somewhat suspicious and already more than a few have speculated online that maybe someone who was shorting Tesla Stock wanted to get out from under that burden and may have staged the accident... well, maybe if it was James Bond driving.

So now we have 3 burned Teslas from roughly 25,000 on the road so does that make Tesla unsafe? Nah! Their accident percentages are still way below regular gas cars on a per mile basis and Teslas do provide over the top protection in several other safety metrics that other cars can not match.  Add to that; one of the three accidents, the primary cause was alcohol.  The enormous damage sustained by the car still allowed the driver to walk (or rather stagger) away from the accident without much more than a scratch.  What is most certain is the high likelihood that any car would have caught fire and a real level of uncertainty concerning the well-being of a driver in a different car.

So to create a battery fire in an EV, a lot has to happen.  First there has to be a puncture in the battery pack, then one of the many flammable fluids has to leak and catch fire as well. But as we have already seen; Enough Murphy's Law combined with plain old bad luck can be overwhelming!

But there are nearly 100,000 LEAFs out there and NONE of them have had their batteries burn and amazingly, this also includes a LEAF in the Colorado Springs fire that did burn up but left the battery pack INTACT.   Now the Colorado Springs LEAF was not in an accident so none of its protections were compromised so it would be different right?  Ya, BUT...

We need to look at the types of accidents in the two road debris cases and the likelihood of them being repeated on anything resembling more than "hit by lightning twice" odds.   Being essentially impaled by road debris is not common in any circumstances and rightfully so. Unsecured loads that result in property or personal damage carry very stiff fines in this state due to a horrific accident to a young woman several years ago resulting in "Maria's Law" making such an act a criminal one.

Now for any car traveling forward, the likelihood of damage near the front of the car will be much higher than damage at the rear of the car which is pretty intuitive.  Keep in mind; most of the flammable fluids are upfront as well or at least the reservoirs for them are.

So it would make sense to keep the batteries and the fluids as far removed as possible, whenever possible. But the Tesla's battery configuration of being very thin creating a very large footprint for any possible intrusion underneath may need to be looked at.  The LEAF pack is much smaller in capacity but also its exposure to punctures underneath is much smaller. Not sure how big the Tesla pack is but guessing its in the 90 sq feet range. The LEAF modules being rectangular and thicker have an exposure under 10 sq feet.  Add to that the fact that the LEAF battery pack is in the back of the car well away from radiator and brake fluid reservoirs which further reduces a possibility of fire even if the battery casing was compromised.

Now; am I suggesting Nissan did it right and Tesla didn't? Well, we all know both could have made better decisions in several other areas and combating risk in a moving vehicle is always going to be a battle of compromises. With all that said; I would recommend a Tesla to anyone because the basic facts remain; A Tesla may not be as safe as a LEAF in the one respect of battery pack vulnerability; but overall, they are MUCH more safer than nearly any other car on the road today.

If Tesla reduced the footprint of the pack by making it thicker, this would reduce shielding weight as well, so a few positives can be had by this. Now, shifting that much weight around poses other engineering challenges so it would not be a quick or easy fix, but I think its worth looking into.

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