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Rescuers Prep for Hybrid Car Accidents
mykepredko writes "I've driven a Toyota Prius for two years now and found this CNN article regarding the training required to rescue people trapped in hybrid cars to be slightly alarming. As an EE, I would expect that the electrical system is designed to be as well protected and fail-safe as possible in an accident, but if I'm ever in an accident, I'll make sure that any responders are wearing rubber gloves and boots and if any cutting is done, the roof is the only area they touch." Toyota has an accident guide indicating that if the airbags deploy, the hybrid battery pack should be automatically isolated.
vs. dumb-asses.
500 volts? 45 volts is enough to kill you... at 10 amperes!
Seriously, aren't we nerds, or something?!
In the future, I would want to not be isolated from my friends in the Space Station.
From the article:
The battery powering the electric motor carries as much as 500 volts, more than 40 times the strength of a standard battery.
Karma: Can there be a void?
.. -. - . .-. .-. --- -...
Extended comments at Gizmodo makes it clear that this is 99% rumor/FUD. Does anyone bother chacking the facts on these things before they're posted?
OK,
- B
http://www.bradheintz.com/
- updated
As the owner of a 2004 Prius, and being an engineer, I have never felt in danger.
First, the High Voltage system is isolated from the car body completely. Not even "ground" is shared. The cables and parts are shrouded in tough orange plastic.
Second, the article is incorrect on two points: the battery is only 200+ Volts, not 500V. The 500V is only between the inverter and motors.
Also, there are no high voltage components in the doors.
Because the airbag accelerometers are used to monitor whether the car is in an accident, the main battery relay shuts off right next to the battery long before any metal starts twisting its way into high voltage areas. The bigger danger is the battery (several NiMH cells) being split open, but it is protected by its location and special shrouds.
My biggest fear in an accident is that the E-personnel are scared into paralysis by rumors, and don't rescue me.
BTW, you can see the Toyota Emergency Responder guide at http://techinfo.toyota.com/
Nope, most any person who is trapped - dead or alive - has to be pulled out, and since we are the only ones trained to do it, guess who gets called out?
The difference is that we generally wouldn't go emergency if it was a definate body recovery. But IO have certainly cut my share of dead and alive patients out of cars.
The thing about all of this is that, in an accident bad enough, you can't guarantee any emergency system within the car is going to work. I don't care *what* the manufacturer says, if it were my guys they would be wearing any protection we could give them.
The problem isn't just limited to Hybrid cars. Think about the cars that have side-impact airbags, air cushions, etc. Anywhere we want to cut could contain within it an airbag ready to deploy. Worse, even those manufacturers don't have a standard for how long before a system is deenergized. At least with steering wheel airbags we can put a special cover over it.
Random Musings
I don't necessarily believe the original intent of this poster was missed by the moderators. If by his posting his intent was to indicate that the gasoline companies would like nothing more then to discredit the burgeoning alternative energy cars then I think he suceeded. Not that the article is any way incorrect.
I did research on solar power cars back in the late 80's as part of an independent research project at my college. The more I dug into the subject the more I began to discover that all the juicy technical information regarding the subject was owned either by gasoline or oil companies. I was blown away. It was the first time I was confronted with the realities of business. What can I say call me naieve.
Sir, there is a dragon outside with an armful of armor. He's inquiring if we offer free refills.
But after an accident, any part of the wiring harness could be energized relative to the frame -- you just don't know, for example, if the dome light circuit is going to happen to be connected to the same bank of circuits that were smushed into the Big Orange Cable in a front-quarter collision that also happened to damage the fail-safe circuit breakers.
It's a big deal -- I imagine your training is similar to what the rural fire volunteers are getting here in Colorado: if it's a Prius, don't touch it!
Reminds me of the college kids who like to play with radiation warning labels: ``heh-heh. My laptop has a radiation sticker on it! Cool! heh-heh.'' The problem is that if you get in (for example) a car accident and one of those labels is visible anywhere around the car, there is no first aid for you until the radiologic response unit arrives from across town.
Actually, you have been watching too many movies. Gas tanks can't blow up. Gasoline itself is not explosive, only gasoline vapor that has mixed with air is explosive. What this means is that the gas has to first leak all over the place to create sufficient surface area for it to evaporate quickly, and then it has to be ignited. It unfortunately happens, but it's not nearly as easy as most people think. Battery acid also has to evaporate in order to be explosive, and off the top of my head it probably has lower vapor pressure than gasoline.
They still exist. They are called seat belt pre-tensioners and are used on lots of vehicles now. The best occupant protection sytems tend to have belt pre-tensioners.
There are two problems with the above: it neglects the rate of energy transfer and the barrier to it. With a gasoline engine, both are reasonably high unless someone's walking around with matches, and emergency crews are smart enough not to smoke. The risk of shock is higher than detonation.
Also, there's no analogous concept of capacitance for gasoline. However, if the wrong cable gets severed, your ass is fried with an electric. Also, because stored electrical energy is less obvious than a puddle of gasoline, it's harder to avoid.
So there's about 5 reasons why one need fear hybrids in a crash more than regular cars
Another load of premium male bovine excrement from out friends in Texas and Munich/Detroit.
My THIRD Prius, an 04 (I've owned an 01 and 03 - both completely problem-free), is currently sitting in Port Newark. I am also a retired rescue captain so I can state with some authority that Prius fundamental design is such that it would take a deliberate act of stupidity for a rescue technician to manage to make contact with both the positive AND negative high voltage leads at the same time since both are ground-isolated and separately encased in conduit.
In real-fife rear-end accidents, only ONE Prius battery was damaged and it's safety issue was some minimal leakage of electrolyte; NOT "Deadly High Voltage"!
In fact, the Japanese national fire safety bureau (the official name escapes me at the moment) insisted that Toyota place the HV conduit inboard far enough that the "Jaws Of Life" can't possibly make contact in one or two "bites".
Sigh...
"I don't understand it???
I'm afraid of it!
KILL IT!!!"
T_O_M
The Prius uses NiMH batteries. They have a highly caustic (pH 13.5) electrolyte, but other than that are apparently non-toxic. Vinegar or Boric acid can be used to neutralize any electrolyte that leaks, but leaks are not likely since the solution is absorbed into the cell plates and shouldn't normally leak even when the battery module is cracked.
THIS LINK provides a description of how the Prius' drivetrain uses the gas and electric motors in tandem.
FYI, most production cars are incapable of 200. Usually drag is the limiting factor. A late model high-end Camaro or Firebird, for example, with minimal upgrades (chip, intake, exhaust type stuff) will generally drag-limit itself around the 155-170 range dependant on a few factors. A 'Vette in the same boat might make 180-185-ish due to it's better aerodynamics. In any case, even on a wide open empty road, anything over 150 is pretty fucking scary in a production passenger vehicle of any kind - especially taking into account unpredictable things like rocks and small animals that might be in your path.
And generally, you don't get arrested at 100 either. I routinely hit 120 in the major city that I live in when traffic opens up enough to allow it without being overtly rude to other drivers. A little knowledge of where the police usually set up speed traps in your city, combined with a radar detector and a vigilant eye, can usually keep you ticket free even at those speeds.
11*43+456^2
1 - the path through the body is the key - if it passes through the heart at some level (low mA) you can/will/do get V-fib (VF)
2 - you must have voltage to get to the heart - less than 80 will seldom do it, but this depends on skin moisture and pH, how much water you have on board, do you drink Gatorade or just sweat alot...
3 - high-current electrocutions do kill people, because you don't get this high current instantly or constantly - imagine 2 A, followed by a trailing off to 80 mA - gotcha.
4 - Gauss plays some role - if your skin carries the current because it is wet or otherwise highly ocnductive, you may feel a shock at a lower voltage, but no cardiac issues (except fright).
5 - Cars are running on DC, which requires that you basically make contact with two dissimilarly polarized surfaces - it cannot ground to the earth - old electronics technicians only use one hand for this reason.
Stick a 9-volt on your tongue and tell us about it.
Faith is the very antithesis of reason, injudiciousness a critical component of spiritual devotion. Jon Krakauer
No no no,
this thread is going into miss-information fast
The system developed for the Prius was made by a 3rd party company which is partialy owned by toyota. Toyota took their works and continued the development of their system. Ford worked with the same 3rd party company, but largly designed their system theirself (ford by far leads in R&D on hybrids, just haven't put anything out till late summer). They did make a deal with toyota over some of the controls, mainly to avoid patent violations, but it does not share tech, just look at the 2 systems in person and it's obvious, or talk to someone who has worked on one them.
Honda does not use the same type of system at all. The use a integrated flywheel, motor, altenator. It's sandwiched between the engine and tranny. Its a crappy lame hybrid, same thing as GM is putting out in their trucks as an option. Most would not call it a hybrid, at most call it a mild hybrid. But Hondas marketing is at work.
The CVTs in the vehicles are differant. Ford and toyota get their cvt via the planetary gearset used for the powersplite between the engine, generator, motor/wheels. There is no tranny to speed of, just the powersplit unit. The insight and civic use a normal transmission or you can get it with a cvt that is of a complicated deal using cones and belts and what not. They are very differant.
Also there is no patent infringments with using the planetary for the powersplit since this idea is as old as gearing it'self.
Also though you said nothing, i doubt ovonic has any claim over nickel metal hydrid batteries. Since that tech has been around for long anough for any patents to expire, plus their is so many ways to make such batteries you could get around them, and ovonic is more active with lithium ion batteries. And the Ford escape hybrid uses Sanyo batteries if anyone cares.