[001sky]

http://www.nfpa.org/~/media/files/research/nfpa%20reports/ve...

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)

[cma]

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..

[ajcarpy2005]

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?

[yaddayadda]

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!

[sjwright]

Perhaps they could use a radar scanner at the front to look for oversized objects, and react by pumping the suspension up to maximum height?

[cma]

Would probably cause instability and loss of traction (at apex) right before a defensive swerve.

[sjwright]

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.

[jthol]

Does anyone know what the size of this hitch was? What I'm picturing isn't all that large.

[andrew3000]

mercedes has something sorta similar... it adjust the suspension to adjust for pot holes.