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* I posted this comment on the same story elsewhere. Face it, battery technology is not sufficiently advanced to deliver good range without some serious trade

* I posted this comment on the same story elsewhere. Face it, battery technology is not sufficiently advanced to deliver good range without some serious trade offs. The trade off of the Tesla may prove to be the wrong choice long term. No one would ever suggest lining the bottom of a car with a gasoline tank, fortunately we don't have too because the power density is so high. Hence they can put tanks where a collision or road debris damage are least likely to damage them. However Tesla needs a stupendous amount of battery to get its range. Hence we get large cars where they have chosen to isolate the entire pack at the floor of the car. They made the choice to dispense with a central tunnel which could hold more batteries, not use the front engine area or any trunk space. There were two or more reasons for their design choice, first because of the sheer amount of batteries needed and second because of pack swapping. I don't think the trade off is worth it. They can use some of the front "frunk" area to have a raised stack of batteries where the traditional firewall is and do similar in the rear. The could have a raised tunnel down the center line and reduce the need of having batteries so far forward. There were many choices available but they wanted swappable packs. What statistic I want to see is, how many penetration events have their been versus how many fires. How many cells have to be penetrated to create a fire? Is there some flaw that another component is failing during these minor accidents that is causing the fires?

stcredzero 13y ago
As a short term fix, raise the car 1/4", reinforce the front battery section with kevlar, and include a system that can flood at least one of the packs with some kind of fire retardant foam. As a longer term fix, move the battery pack rearward and design in a little more protection.
- moocowduckquack 13y ago
  Just do the foam thing, but do lots of it all round the battery so in the event of a battery fire the battery pops out and is enclosed and the car ends up sitting on a couple of feet or so of foam.
umsm 13y ago
I don't think placement could solve the points you mention. Sure, debris can damage the underside and cause the car to catch fire, but putting the packs in the front or rear of the car can cause it to explode on impact as well. Having it on the underside will probably cause fewer fires than having it in the front for example. That said, consider gasoline cars: The fuel needs to travel from the tank to the engine. Effectively, an impact anywhere on the fuel line can cause a fire.
- stcredzero 13y ago
  packs in the front or rear of the car can cause it to explode on impact as well Uh, yeah. Are you sure Li-ion batteries really explode, or do they just burn really fast? (In much the same way it's very, very difficult to get a gas tank to explode, but not so hard to get it to burn very fast.) I'm pretty sure it's hard to get them to explode.
  - umsm 13y ago
    Regardless of whether they explode, catch fire, burn slowly, burn quickly, the point still stands. Their placement on the underside of the car could probably be the best choice considering everything.
    - stcredzero 13y ago
      There's a big difference between burn and explode.
moocowduckquack 13y ago
No one would ever suggest lining the bottom of a car with a gasoline tank You would be amazed the places people have put gasoline tanks on cars. Just behind the rear axle has been one of the stupidest, so it goes boom when someone drives into the back of you. http://www.autosafetyexpert.com/defect_fueltank.php http://www.autosafetyexpert.com/defect_fueltank.php
scoot 13y ago
How many cells have to be penetrated to create a fire? Just the one: 'if crush or penetration occurs perpendicular to electrode edges, that deformation is likely to result in high impedance shorting between electrode layers and initiate cell thermal runaway.'[1] This is an incredibly thorough piece of research: [1] Celina Mikolajczak et all, (2011), Lithium-Ion Batteries Hazard and Use Assessment (p. 57, paragraph 5) Retreived from: http://www.nfpa.org/~/media/Files/Research/Research%20Foundation/Research%20Foundation%20reports/Hazardous%20materials/rflithiumionbatterieshazard.pdf http://www.nfpa.org/~/media/Files/Research/Research%20Founda...

stcredzero 13y ago

As a short term fix, raise the car 1/4", reinforce the front battery section with kevlar, and include a system that can flood at least one of the packs with some kind of fire retardant foam. As a longer term fix, move the battery pack rearward and design in a little more protection.

moocowduckquack 13y ago
Just do the foam thing, but do lots of it all round the battery so in the event of a battery fire the battery pops out and is enclosed and the car ends up sitting on a couple of feet or so of foam.

umsm 13y ago

I don't think placement could solve the points you mention. Sure, debris can damage the underside and cause the car to catch fire, but putting the packs in the front or rear of the car can cause it to explode on impact as well. Having it on the underside will probably cause fewer fires than having it in the front for example. That said, consider gasoline cars: The fuel needs to travel from the tank to the engine. Effectively, an impact anywhere on the fuel line can cause a fire.

stcredzero 13y ago
packs in the front or rear of the car can cause it to explode on impact as well Uh, yeah. Are you sure Li-ion batteries really explode, or do they just burn really fast? (In much the same way it's very, very difficult to get a gas tank to explode, but not so hard to get it to burn very fast.) I'm pretty sure it's hard to get them to explode.
- umsm 13y ago
  Regardless of whether they explode, catch fire, burn slowly, burn quickly, the point still stands. Their placement on the underside of the car could probably be the best choice considering everything.
  - stcredzero 13y ago
    There's a big difference between burn and explode.

moocowduckquack 13y ago

No one would ever suggest lining the bottom of a car with a gasoline tank You would be amazed the places people have put gasoline tanks on cars. Just behind the rear axle has been one of the stupidest, so it goes boom when someone drives into the back of you. http://www.autosafetyexpert.com/defect_fueltank.php http://www.autosafetyexpert.com/defect_fueltank.php

scoot 13y ago

How many cells have to be penetrated to create a fire? Just the one: 'if crush or penetration occurs perpendicular to electrode edges, that deformation is likely to result in high impedance shorting between electrode layers and initiate cell thermal runaway.'[1] This is an incredibly thorough piece of research: [1] Celina Mikolajczak et all, (2011), Lithium-Ion Batteries Hazard and Use Assessment (p. 57, paragraph 5) Retreived from: http://www.nfpa.org/~/media/Files/Research/Research%20Foundation/Research%20Foundation%20reports/Hazardous%20materials/rflithiumionbatterieshazard.pdf http://www.nfpa.org/~/media/Files/Research/Research%20Founda...