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Why Electric Cars Are Safer

9/9/2013 11:35 AM EDT
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Jack.L
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Re: Safe? Think Again
Jack.L   9/10/2013 9:25:30 AM
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Lithium Ion batteries are only "toxic" if they burn in which case they do release toxic chemicals. On their own they are considered non-hazardous waste and can be put into a land fill.

There are also many lithium ion chemistries and their potential for catastrophic failure varies considerably. Your typical cobalt electrode lithium ion cell has the potential for thermal runaway if mechanically damaged or through manufacturing defect. LiFeP04, on the other hand, is fairly immune to abuse.

That 400V "cage" requires obviously a positive and negative connection in order to be a shock hazard. I am not saying a shock hazard is impossible, just the likelyhood of an isolated power source becoming a shock hazard is remote. Even if one of the power leads shorts to the metal body, where would be the return path for a shock?

junko.yoshida
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Re: electric is the future.
junko.yoshida   9/10/2013 12:23:49 PM
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@betajet, how about this, then?

Qualcomm is working on what it calls Halo wireless electric vehicle charging (WEVC) technology.

See my other story:

The inductive-charging scheme wirelessly beams power to receiving coils on an electric vehicle. More specifically, a coil built into an electric vehicle will pick up an electromagnetic pulse as the EV runs over a copper pad buried in the ground.

So, if we bury those pads on streets, yeah, you probably won't have to go to a refueling station!

cookiejar
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safety tests invalid
cookiejar   9/10/2013 12:38:11 PM
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Unfortunately, neither race track handling tests nor safety crash test results agree with highway fatality statistics. 

The Insurance Institute's website www.iihs.org has both sets of data.  Driver death rates   http://www.iihs.org/iihs/topics/Driver-death-rates   tell quite a different story from the crash tests. 

 A most glaring example of the real world not following theory is in the April 17, 2007 Status report, which showed the safest vehicle on the road at the time to be the Chevy Astro van as based on driver deaths per million registered vehicle years.  This van, virtually unchanged in design since 1985, which came almost dead last in crash tests, braking tests, and handling tests proved to be the safest vehicle on the road with an overall death rate of 7 per million registered vehicle years! 

 In comparison, Mercedes E class was 14, Ford F150 was 118, Ford Excursion was 115, Chrysler 300M was 115, Dodge Neon was 161, Volvo S40 was 89, VW Golf was 45 and on and on.  Overall, large mini vans as a group were 66, proving the old design almost ten times safer than the newer ones.

 Since contractors drive a lot of Astro vans pretty hard, overloaded and poorly maintained, its primitive design must hide some life saving secrets.

 In science and engineering, when a theory bears no resemblance to the real world, one throws out the theory and starts again.  A good place to start is to do a careful analysis of the Chev Astro van to figure out why it did well and change the crash and handling tests based on the results to more closely resemble the real world.  Once this is done, new designs can be expected to be significantly safer.

 Perhaps one secret to the Astro van is its lack of distracting electronics and straightforward controls, not requiring one to take one's eyes off the road.  At any rate, when it comes to vehicle safety, the only thing that counts is the death rate on the road.  Let me repeat, for all you engineers out there, this isn't a time wasting endeavor, but is a matter of life and death.

 

 

 

cookiejar
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Re: electric is the future.
cookiejar   9/10/2013 12:53:56 PM
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I don't think swapping would work too well as someone would inevitably get stuck with a dud battery that won't get his car to the exchange station.  If I were an operator of an exchange station, I wouldn't want the dud either.
Years ago I bought a brand new full acetylene B tank.  Since it takes a long time to recharge these tanks, the practice is to go to a depot and swap for a full one.  One day I got stuck with the last rusty old tank.  Now nobody will take it in exchange accusing me of neglecting it.
 As a footnote, the acetylene B tank has been around unchanged since the 1800s judging by the one on display at one welder supplier.  Unlike oxygen tanks that need to be regularly pressure tested, these tanks have no rules regarding inspection.

TanjB
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Re: electric is the future.
TanjB   9/10/2013 12:53:56 PM
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Cheaper and more efficient just to run contact wheels over electrode patches on the road.  Self driving cars should be able to align with contact regions and feedback interlocks can ensure the power is off unless a moving vehicle is passing by.  You might even be able to use conductive structures in the main tires.

Induction methods not only have efficiency problems but are like to be order(s) of magnitude more expensive to embed in the road.  You need resonant coils and reflectors, careful alignment, high current pulses modulated to track moving cars - far more complex than an embedded conductor path with safety interlocks.

Main drawback of contacts is likely to be in northern regions subject to snow.

TanjB
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Re: Safe? Think Again
TanjB   9/10/2013 12:58:29 PM
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Low temperature fuel cells do not deliver power.  They can store the energy, but for a given weight and cost only a trickle of power.  They also tend to need very pure fuels to avoid poisoning the expensive electrodes.

A low temp fuel cell might eventually make sense for trickle recharge, if the trickle can get into the kW range for reasonable weight and cost.

junko.yoshida
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Re: electric is the future.
junko.yoshida   9/10/2013 1:00:09 PM
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@TanjB, good point. You wrote:

Cheaper and more efficient just to run contact wheels over electrode patches on the road.  

Has this ever been tried anywhere yet?

TanjB
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Re: electric is the future.
TanjB   9/10/2013 1:03:10 PM
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You might want to find safe disposal of that rusty acetylene tank.  They can be spectacular when they fail.  The interior of the tank is filled with adsorbant (a clay, IIRC) to stabilize it, cracks and free space accumulating pressurized acetylene will spontaneously explode.

If it is completely discharged by now then maybe not such a worry.

chanj0
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CEO
Re: Safe? Think Again
chanj0   9/10/2013 1:20:16 PM
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EmbeddedSteve718 raises a couple good points. I think we need to understand what the objectives of the road safety tests. Roll over hazard, side impact are primarily related to the mechanical design of the vehicle. The lowest the center of gavity, the safer the vehicle. It has always been the objective of any car makers. Unfortunately, due to the inherent nature of gasoline engine, the center of gavity can go so far. The H-type engine designed by Subaru has improved the center of gavity and yet, it can't beat the heaviest component - battery pack - being put in the almost lowest point of a Tesla Model-S.


Going back to EmbeddedSteve718's points, I believe there are a couple more tests that shall be included to rate the safety of an electric vehicle. I am sure the industry will continue evolve and I still believe electric vehicle is our future of transportation.

Andrzej11
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CEO
Re: electric is the future.
Andrzej11   9/10/2013 3:12:01 PM
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@Junko

Given that the US has over 4 million miles of public roads and over 600,000 bridges with one in ten being structurally deficient with an estimated $78 billion repair bill, the notion of now electrifying this aging infrastructure with inductive charging seems a bit unrealistic.

However inductive charging mats for parking areas such as your garage are sure to dominate the charging infrastructure a few years down the road. Nissan is delaying its Infiniti branded EV until the technology is more mature as it wants to launch its EV for the Infiniti line with inductive charging.

BTW, Tesla has stated it hopes to bring to market a DC fast charger with a 5 minute charging time! Just imagine the strain a whole bunch of these 1 MW chargers would have on the distribution grid. If they are successful then road electrification would be clearly be unneeded.  

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