*IMO Don't buy a 2K4 Prius and if you own one don't drive it

I'm sorry to hear of all the aggravation this has caused. Dealing with insurance companies and getting them to make things right can be incredibly frustrating.

But I'm still not completely convinced that this is a design flaw.

Perhaps most importantly, this accident proves that the plastic tray is a significant reinforcement, strong enough to stand up to at least a mild accident. This is advantageous in the case of an offset collision. If a car hits you from behind in such a way that it's force is transferred to a small part of your rear end, then you want as much material in back reinforcing the area and distributing the pressure of the accident over a wide area. That prevents intrusions into the passenger compartment, protecting passengers.

The plastic seems to transfer some of the impact onto the battery casing, which is presumably very solid and well anchored to the frame. The battery casing is not the battery, and small deformations of the casing do not necessarily mean there is battery damage (although it's certainly something that should be checked carefully). It could be a good design to have the energy of the collision go into deforming the battery casing.

It could also be a good thing that the plastic is prevented from sliding up and over the battery since that could cause an intrusion into the passenger compartment, if the back seats were down or if it went through the back seats.

One very well known trend is that as cars become safer, they are becoming more expensive to fix. In some sense this plastic tray and the battery casing are a part of the body of the car, taking some of the collision impact. When cars had steel frames with body panels mounted to them, collision damage was very localized. But unibody frames mean damage is spread over a wider area. This is another example of damage being spread over a wider area.

My intuition is that the plastic tray is not strong enough to seriously damage the battery. After all, the battery itself is encased in plastic (inside the aluminum casing). If the battery plastic is at least as strong as the tray plastic, then the tray plastic is likely to take more damage simply because it is much larger.

Finally, as someone who has worked on electric vehicles and knows about safety of high voltage batteries, I can say I have absolutely no fear over electrocution due to trauma to the battery. Previous posters have pointed out that you would require not one but two independent electrical paths to the victim for a shock to occur. Even if the frame of the car were to get connected to the positive terminal of the battery due to trauma, there still would be no potential unless the victim somehow managed to find some other metallic path to also touch the negative terminal.

One important safety difference between batteries and household power is that batteries are not referenced to ground. By that I mean that you could have your bare feet in a salt puddle on top of a grounding rod and touch the positive terminal (or negative terminal) of the Prius battery and zero current would flow through you. Don't try that with household current though... you'd get fried touching the hot wire from your household plug in those circumstances.

The reason for the concern about accident responders is that they do often stick metal objects (jaws of life, towing equipment, etc) into places where the high voltage lines run. It's theoretically possible (although not particularly likely) that a scenario like the following could occur:

1. Despite trauma to battery, airbags didn't go off and so HV battery relays didn't shut off.
2. Due to trauma, the negative HV terminal has become connected to the car chassis. Note this is not true normally and there is insulation to prevent this from occuring easily.
3. Responder pierces a wire to the HV positive terminal with the jaws of life.
4. Responder has one hand on car chassis and one hand on a metal part of the jaws of life, and therefore gets shocked. Note that the fuses would limit the current, but it could still be life threatening.


If any one of those things were not true, no shock would occur. Because passengers in cars don't normally carry or use tools that have the potential to pierce the insulation on an HV wire (which does not run through the passenger compartment), my assessment is that there's no electrocution risk to the passengers.


I wish you the best of luck in getting your car back in shape, and thank you for providing this information for us to chew on.

 

I actually totally disagree, if the situation allows and I had another car that was usable until another Prius could be obtained, I would have the car totaled in an instant.

And would not future resale value be compromised by having to divulge that the car had been in an accident.
Maybe Toyota should take this crashed car in it's particular condition and study to make proper repairs.

As far as scarcity/expense of parts, is it not this way with “new†vehicles at least when they first come out, especially with ones so advanced as the hybrids. I would assume it takes time to fully unwrap this technology and we as pioneers may not always find things to run smoothly. The lack of, expense of parts, untrained technicians, all these will be solved as more time passes I would assume.
On the other hand, I hope Toyota tackles this safety issue with immediate attention.
Will that mean all the ‘04s so far will probably be getting a recall? Or will they just leave the ‘04s and make changes to the ‘05s? I wonder.

 

You don't really need an emergency cut-off button, the power button will cut power to the moter and inverter, and I believe it will also cut the battery relays to seperate the battery cells. While turning the car off after an accident is probably not at the top of your mind after an accident, but it is more likely than locking for a an emergency cut-off.

I also agree with the prevouis posts, that the chances of a dangerous shock are very remote. I think it's much more dangerous carrying around 10 gallons of gasoline. And in other cars, it's in an unlined tin can!

 

The newly-appointed CEO of Delta Airlines is from Seattle.

A week before he was to drive his new '04 to Atlanta, he got rear ended, big time.

About $ 24,000, I'm told by Exotic Motors , the body shop of choice in Bellevue, WA. I know them. They are in fact damned good.

They fixed the car, in the owner's opinion, "as good as new" and he drove it to Atlanta.

This guy can buy and drive any damned car he wants.

It would be interesting to hear his take on rear end damage, etc.


Bob

 

Frank, I totally agree that your battery needs to be checked out and if they can't do complete tests to verify that it's okay they should assume it's bad and replace it.

I have never heard anything about batteries being particularly susceptible to dropping. Where did you learn that?

In my experience however if I drop a flashlight with batteries, the flashlight is much more likely to have a reduced lifespan or be damaged than the batteries. Same goes for just about anything with batteries.

The only reason I can think why batteries might be especially susceptible to drops is that batteries are generally more dense than other things, and so when you drop one on a hard surface, there is more momentum transferred to the impact point than would be true of a lighter (less dense) object. Certainly dropping a 50 pound car battery on cement would be likely to cause a dent that could disable it. Whereas dropping say the plastic tray on the same cement probably wouldn't be a problem.

But in your accident the battery density isn't involved as much. The impact on your battery casing seemed to be caused by the plastic tray pushing forward on the battery casing while the bolts on the bottom of the battery casing hold it back. That kind of twisting moment impact doesn't involve deccelerating the battery suddenly as the cement drop would, and so the mass of the battery is much less important.

As far as the 12V system being attached to the HV system, that is true, but it is isolated. The 12V ground (which is the vehicle chassis) is not directly connected to either of the HV terminals in the DC/DC inverter. I used to own an electric vehicle where the HV battery was directly connected to the 12V ground (and chassis). That was a safety nightmare, widely condemned as a bad design. Toyota wouldn't (and didn't) make that mistake.

Toyota definitely should be taking the lead on this; they should have standards and procedures for testing batteries. If they don't you should raise hell with 'em.

 

It should be noted that the battery in question is a bunch of small NiMH (alkaline electrolyte) cells, not a lead acid battery. The latter is much more likely to damaged by shock because the lead plates can crack. Since the cells can be individually replaced, I would think major impact would be more likely to separate them than to cause a short.

 

Just my two cents but I have to also disagree with the conclusions in the original post. I looked at the rear load floor in my Prius and it is located above and not in-line with the HV battery pack. The next large object that could impact the battery (the spare tire) is located below the pack. The load floor is slightly wider then the rear wheelwells and would have to push through them also. If the battery terminals were somehow "shorted" inside the steel container, thats where the short would be----not exposed to people in the vehicle. I did note that the pictures showed that the passenger cabin held up very well in the accident. It was stated that the car was pushed 10-12 feet and into the rear of another vehicle. That's a pretty good hit. Cars can be repaired or replaced---people cannot. The purpose of crash design is to protect the people in the vehicle, not the vehicle or component parts of it! :idea:

 

If anything, I think that this crash illustrates why we need better SUV standards put into place. The bumpers are too high and the vehicles are far too heavy.

IMHO, if you're driving a 5,000-6,000 pound monster around, you should be required to have a special license and harsher penalties in the event of an accident (that's your fault). They already do this for truck drivers and heavy machinery drivers. Why not SUVs? They're heavy machinery.

 

Well, maybe large SUVs and, while we're at it, we might as well include those monstrously huge pickups.

My son's CRV weighs about 3300 lbs and the bumper lines up somewhat evenly with our Accord. I don't think we need "better standards" for SUVs in that category.

Speaking of bumper height, I saw an H2 yesterday that I just couldn't believe; huge tires and jacked up at least a foot over a standard H2 with some sort of suspension mod. From the looks of it, the bumper would probably clear the roofline of the Prius. I found something similar to the H2 I saw on the internet.

[Broken External Image]:http://www.todayssuv.com/features/0312suv_h201_z.jpg

 

Frank,

Just seeing that thing, parked, in a movie theater parking lot was enough to put the fear of God in me!

 

Agreed!

However, if I can just outrun it for 30 miles, I can wait for it to run out of gas. :mrgreen:

 

You could also outrun it by taking 2 or 3 left turns and making it overturn. :lol:

 

There's just no excuse for the Hummer H2. What a waste of resources!