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Old 10-03-2013, 01:08 PM   #321
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The EPA estimate is based on roughly 280 watts/mile. On my rare 20+ mile trips to the other end of the island at 65 MPH I am actually getting that type of efficiency.
However in my case I take short trips 5 miles or so and all of my trips start at 1100' end up at sea level and then go back up the steep hill. So I am actually get 350 watts/mile. To be fair I recover about 1/2 the energy going down hilll which an ICE doesn't do. It is conceivable that upon a rare occasion I may accelerate in an energy inefficient manner
That is really efficient, my Ford Focus Electric has averaged 257 watts/mile for the last 3 months, about 600 miles a month. But this is a lighter car and although it drives as fast as an ICE Focus I assume the Tesla is driven in a more sprightly manner

The local municipal utility has pretty good rates, I have a TOU meter and over the last 11 months I calculate equivalent electric charges to 100 to 110 MPG at home. Only use commercial charging occasionally and that brings down the MPGe,. $1.13 added 16 miles recently, since gas locally is $4 gal that works out to 60 MPGe. What is the charging rate for the superfast Tesla chargers?
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Old 10-03-2013, 01:30 PM   #322
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I think that it is only news because it is new technology. ....

Summary: Yawn.
That was my take on it when I saw this earlier. Conventional cars burn up too, is this really out of the ordinary?

But, I do have some questions. Just how limited are the fire-fighters? Three-to-four hundred volts is dangerous. Does it make handling these problems significantly different?

And what about the environmental impact? Sure, 12 gallons of gas burning uncontrolled is not good, but it doesn't seem to be too big a deal. But what about a 55 kWh battery pack burning up? What nasties does that release?

In a similar vein, there have been reports going around about the dangers of fighting fires in buildings with solar panels on them. At first I figured those were hack pieces written for the green skeptics, but they made some interesting points. You can't just turn them off (like cutting power and gas to a building at the meter), they produce power at each panel. They said that even at night, the lighting they use could create problems. That seemed a stretch, but maybe not - a solar panel will produce near full voltage with only a little light, it just won't be able to deliver much current. But it does not take a lot of current to electrocute someone. And a firefighter can't know what the load is on these things.

I wonder if this will drive up insurance costs on large solar installations?

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Old 10-03-2013, 01:35 PM   #323
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travelover, this very thing is what happened with the Tesla "S" fire. Read in the paper this morning that the vehicle struck an object lying in the road and somehow got to the batteries. They will be all over that situation like white on rice to come up a guard against things like that.
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Old 10-03-2013, 02:00 PM   #324
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They said that even at night, the lighting they use could create problems. That seemed a stretch, but maybe not - a solar panel will produce near full voltage with only a little light, it just won't be able to deliver much current.
It seems like a stretch. If we start with the wattage of the firetruck lights, then reduce for their efficiency (electric watts to light watts), then figure only a small % of that, will actually strike a panel, then reduce a considerable amount for reflection loss due to the highly oblique angle of incidence in this case, and finally reduce for the very low efficiencies of these panels, it doesn't seem likely the typical residential installation would produce much juice under typical circumstances.
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Old 10-03-2013, 03:01 PM   #325
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travelover, this very thing is what happened with the Tesla "S" fire. Read in the paper this morning that the vehicle struck an object lying in the road and somehow got to the batteries. They will be all over that situation like white on rice to come up a guard against things like that.
I guess I was unclear. My point was that road debris can kick up and cause a fire in a conventional car, too.
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Old 10-03-2013, 04:08 PM   #326
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...What is the charging rate for the superfast Tesla chargers?
For the 85 it is free. For the 60kWh, supercharger access is an option. I believe it is $2000 or so. Once you have the option, superchargers are free.

Quick note, the EPA for the 85 is based on 308 watts/mile.
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Old 10-03-2013, 04:27 PM   #327
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I guess I was unclear. My point was that road debris can kick up and cause a fire in a conventional car, too.
Yeah, I went back and reread your post. Missed that a little.
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Old 10-03-2013, 06:12 PM   #328
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It seems like a stretch. If we start with the wattage of the firetruck lights, then reduce for their efficiency (electric watts to light watts), then figure only a small % of that, will actually strike a panel, then reduce a considerable amount for reflection loss due to the highly oblique angle of incidence in this case, and finally reduce for the very low efficiencies of these panels, it doesn't seem likely the typical residential installation would produce much juice under typical circumstances.
You're right, I think. If they had 10KW of lighting, and it was high efficiency, that might be 4KW of light. Times 10% eff of a solar cell is 400 watts assuming the panel collected all the light, which will obviously be much less.

But even 100 W is 1A at 100 Volts, and that's enough to be dangerous, but it would seem extremely unlikely for that 1A to find it's way through a person's body. Hmmm, googling says even 30mA can cause defrib, but that's under 'best/worse' conditions.

So I'd agree it is a stretch, but it might still be a concern. OTOH, I think the danger in sunshine is very real. The article I saw, it sounded like the firefighters pretty much let the place burn rather than take a chance spraying with water. Maybe they need an opaque foam to use for these cases?

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Old 10-03-2013, 07:34 PM   #329
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I guess I was unclear. My point was that road debris can kick up and cause a fire in a conventional car, too.
On my drive home today, I saw a car in flames on the other side of the road. It looked like a conventional internal combustion powered vehicle. I think they might be dangerous.
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Old 10-03-2013, 07:41 PM   #330
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On my drive home today, I saw a car in flames on the other side of the road. It looked like a conventional internal combustion powered vehicle. I think they might be dangerous.
hah. But we need more data points since Tesla has only sold 12,000 cars or so.

Is it the norm for 1 out of 12,000 ICE vehicles to catch on fire when they run over a hubcap? (I honestly don't know the answer)
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Old 10-03-2013, 07:52 PM   #331
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On my drive home today, I saw a car in flames on the other side of the road. It looked like a conventional internal combustion powered vehicle. I think they might be dangerous.
One thing the EV has in it's favor - it is much more efficient than a conventional ICE in converting the battery power (versus gasoline) to power at the wheels. The conversion losses where done at the power plant.

So the total energy in the battery pack is less than the total energy in a gas tank. But, as I mentioned earlier, what is the environmental impact of burning a 55 kWh battery pack, versus 4x or 5x that much energy of burning gasoline?

Lithium and all those other chemicals are probably pretty nasty stuff.


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hah. But we need more data points since Tesla has only sold 12,000 cars or so.

Is it the norm for 1 out of 12,000 ICE vehicles to catch on fire when they run over a hubcap? (I honestly don't know the answer)
Agreed. We will have to see, I guess.

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Old 10-03-2013, 08:08 PM   #332
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Is it the norm for 1 out of 12,000 ICE vehicles to catch on fire when they run over a hubcap? (I honestly don't know the answer)
Depends. Is it a '79 Pinto with Firestone tires?

Very roughly 1 in 1000 vehicles will have a fire in any given year. I couldn't find any statistics on fires per run-over hubcap. Siri?


http://tkolb.net/FireReports/US_VehF...t2003-2007.pdf
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Highway vehicles account for the vast majority of vehicle fires and associated losses.
Ninety-three percent of reported vehicle fires and 92% of vehicle fire deaths involved highway-type vehicles such as cars, trucks, buses, recreational vehicles, and motorcycles. The term “highway vehicle fires” is used to describe the type of vehicle, not the location of the fire. During 2003-2007, the 267,600 highway vehicles reported per year caused an average of 441 civilian deaths, 1,326 civilian fire injuries, and $1.0 billion in direct property damage. On average, 31 highway vehicle fires were reported per hour. These fires killed one person a day. Overall, highway vehicles fires were involved in 17% of reported U.S. fires, 12% of U.S. fire deaths, 8% of U.S. civilian fire injuries, and 9% of the direct property damage from reported fires.
According to the U.S Federal Highway Administration data, roughly 2,980 billion miles were driven, on average, per year on U.S. roads during this period. Roughly 90 highway vehicle fires and 0.15 highway vehicle fire deaths were reported per billion miles driven.
Some form of mechanical failure or malfunction, such as leaks or breaks, backfires, or worn-out parts, contributed to 49% of the highway vehicle fires and 11% of the associated deaths. Electrical failures or malfunctions contributed to 23% of the highway vehicle fires but less than 1% of the associated deaths. Although collisions or overturns were factors in only 3% of the fires, 58% of the deaths resulted from these incidents. Older vehicles were more likely to have a fire caused by mechanical or electrical failures.
Eight percent of the highway vehicle fires were intentionally set. More than half (54%) of these intentional fires originated in the operator or passenger area
Almost two-thirds (64%) of the highway vehicle fires began in the engine, running gear, or wheel area. Thirty-five percent of the associated civilian fire deaths, 46% of the civilian fire injuries, and 53% of the direct property damage resulted from fires that originated in this type of area. Only 2% of the highway vehicle fires started in the fuel tank or fuel line area but these fires caused 18% of the associated deaths.
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Old 10-03-2013, 09:55 PM   #333
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One thing the EV has in it's favor - it is much more efficient than a conventional ICE in converting the battery power (versus gasoline) to power at the wheels. The conversion losses where done at the power plant.

So the total energy in the battery pack is less than the total energy in a gas tank. But, as I mentioned earlier, what is the environmental impact of burning a 55 kWh battery pack, versus 4x or 5x that much energy of burning gasoline?

Lithium and all those other chemicals are probably pretty nasty stuff.




Agreed. We will have to see, I guess.

-ERD50
Lithium batteries for hobby applications, like R/C planes/cars/boats, are supposed to be OK to throw in the regular trash after making sure they are fully discharged. They're not particularly dangerous when not charged.
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Old 10-04-2013, 08:42 AM   #334
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hah. But we need more data points since Tesla has only sold 12,000 cars or so.

Is it the norm for 1 out of 12,000 ICE vehicles to catch on fire when they run over a hubcap? (I honestly don't know the answer)
They have approximately 18 to 20k cars sold.

Was it a hubcap? I would be very concerned if it was. Do you have a link?
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Old 10-04-2013, 05:18 PM   #335
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Was it a hubcap? I would be very concerned if it was. Do you have a link?
Reuters says Tesla confirmed the vehicle caught fire after running over a "large metallic object." The report offered no further specifics on the type of object, but (IMO) it makes a difference if it was a hubcap, a 4' long metal pipe, or an aluminum ladder.

Other items of interest from the report at the link:
Quote:
Given that Tesla's Model S and the discontinued Roadster have been driven a combined 113 million miles and that this was the first battery fire, the company's rate of catching fire was still only one-tenth the frequency of conventional car fires, Wedbush Securities analyst Craig Irwin said. He has a "neutral" rating on the stock.
Tesla officials said the battery and the car worked as designed, keeping the fire under control and allowing the driver time to pull over and safely exit the vehicle.
"The fire was caused by the direct impact of a large metallic object to one of the 16 modules within the Model S battery pack," Tesla spokeswoman Elizabeth Jarvis-Shean said.
"Because each module within the battery pack is, by design, isolated by fire barriers to limit any potential damage, the fire in the battery pack was contained to a small section in the front of the vehicle," she added.
Still, the firefighters apparently had a tough time getting things under control. The water they used at first made things worse, and only when they used dry chemical extinguishers did the fire go out. IIRC, water is typically used to extinguish Li Ion battery fires in laptop computers, but it takes a lot of it, and the colder, the better (ice helps).
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Old 10-04-2013, 11:21 PM   #336
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Got an email from Tesla. Didn't sound like a hub cap. It was strong enough to "pole vault" through the 1/4" thick battery compartment bottom and leave a big hole. The batteries are segmented into 16 firewalled compartments. One was breached. Tesla said it was OK to use water on their batteries, but the firefighters also broke through several of the adjacent battery compartments, spreading the fire. The top portion of the battery structure was intact after the accident, the fire did not enter the cockpit.

They also said the driver was alerted by a warning system and was able to exit the highway and get out in plenty time.
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Old 11-13-2013, 02:04 PM   #337
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So there has been a third Model S fire. This still seems to be below average statistically, but I wonder. I think the data that Musk referenced was for total car fires divided by total miles annually - but what if we looked at fires only in new cars (less than 1 year old)? I'm guessing older cars have more fires, leaks, oil drips, and other maintenance issues would likely tilt the numbers?

I got curious and looked at a diagram of the Model S. They spec ~ 6" ground clearance, and it looks like the battery pack extends about the width of the car and from front to rear wheels. Now that's about 40 square feet of battery sitting ~ 6" from the ground (behind a shield). That seems like a lot of area vulnerable to road debris.

Then I looked at our Volvo S40 and Honda CR-V. Each gas tank was ~ 2' x 2', so 1/10th the area exposed as the Tesla. And the clearance on each was 11" and 14" minimum. And, the gas tanks are tucked behind the rear axle, which is much lower, and would provide a lot of shielding. Those three factors combined seem very significant to me.

I'm starting to think this might be a real issue for Tesla. I think the Roadster had the pack tucked up behind the seats, not exposed to the ground like the Model S.

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Old 11-13-2013, 02:15 PM   #338
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Probably not too useful to try and make conclusion on 2 incident. The fire in Mexico was caused by entering a roundabout at about 90 MPH and then crashing through a concrete barrier, I'd say the road clearance was the least of the guys problems and wasn't a factor. He is very lucky to be uninjured.

My understanding was the first fire in Washington would have also caused a collision in a normal vehicle because it was a few foot high object, it may or may not have hit the gas tank (remember there are also fuel lines which can be punctured.)

Now this last case we don't know how high the trailer hitch is but it is certainly possible that a car with more ground clearance would have gone over it without an incident.
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Old 11-13-2013, 02:59 PM   #339
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The ground clearance at speed in cars with the air suspension is actually even less.
And your point about the larger surface area that can be impacted is valid as long as you include workings of an ICE car other than the gas tank that can also cause issues.

What I would ask next, is how many road debris collisions in other vehicles cause accidents, deaths or personal injury?
My guess would be it is more than 2 per 110 Million miles, and those typically would not be more or less likely in newer or older vehicles (WAG).
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Old 11-13-2013, 03:23 PM   #340
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Probably not too useful to try and make conclusion on 2 incident. ...
Agreed, but the factors I mention do make me wonder what we will see on a larger sample. That sure seems like a lot more exposure to me (10x the area, closer to the ground, and fewer other things to intercept the material before it sees those batteries). I find that difficult to ignore.

Looking at the link that MP posted earlier -

http://tkolb.net/FireReports/US_VehF...t2003-2007.pdf

Quote:
Collision, knock down, run over, or overturn - (3%)
I guess 'road debris' (if that is what they mean by 'run over') is listed along with other things, and the percentage of road debris fire incidence does seem very low. But that means (based on a tiny sample size), that this type of fire would be very high for Tesla - which would back my question: is this an issue for them?

Of course, if the Model S proves to be safer over-all, maybe this is too much slicing/dicing. But I still say that much battery that low looks vulnerable.

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