electric car hazard

[exxon]

the easiest thing is to understand the concept of "circuit". a circuit is a ring closed which includes one or more elements equipped with two terminals. only in a closed circuit, it circulates current.

if you take the battery from 400 v and with one hand touch a terminal, when with the other hand touch the other terminal, "close the circuit" (and stains flashed).

When you touched the first of the terminals, there was no circuit yet, there was no current and you could not notice anything. even if you had your feet in the water, because the second battery terminal was "flying", not connected to anything.

if one or more elements that are part of the circuit are insulating, the circuit is "open" and the current does not circulate. as an example we take the battery first, but we touch the two terminals with a rubber glove on one of the hands. Now, the circuit has also joined the piece of rubber between the hand and the pole of the battery. the rubber is insulating, the circuit is open, the current does not pass and you survive.

there are not only conductive materials (such as metals) or insulating materials (such as rubber). There are countless intermediate cases. the ground is one of these. If the soil is wet, a bit of current makes it pass, if it is dry just not. fresh water is a bad conductor, sea water instead is a good conductor.

if one or more elements of a circuit are these "intermediate" materials, the amount of current flowing (and consequently the effects it generates, including the possible lightning) are directly proportional to their goodness as conductors. the other factor is the voltage of the generator: if the generator is 400 v, in order to have concrete effects, All circuit elements must be good conductors. if instead I have a generator of 10000 v (like that in electrified fences), although one or more elements are bad conductors (but not insulating), as in the case of wet soil, then I will still have an obvious effect.

 

[Fulvio Romano]

This link is depopulating. is not an article, but an anonymous letter (anonymous!!!) of an unknown reader which was published in an integral way. And on...

 

[cacciatorino]

This link is depopulating. is not an article, but an anonymous letter (anonymous!!!) of an unknown reader which was published in an integral way. And on...

apart from the mildly rude tone on which I prefer to fly over, it comforts me that even you say that a 400V battery and several current ampers does not constitute any danger, thank you.

 

[cacciatorino]

the easiest thing is to understand the concept of "circuit". a circuit is a ring closed which includes one or more elements equipped with two terminals. only in a closed circuit, it circulates current.

if you take the battery from 400 v and with one hand touch a terminal, when with the other hand touch the other terminal, "close the circuit" (and stains flashed).

When you touched the first of the terminals, there was no circuit yet, there was no current and you could not notice anything. even if you had your feet in the water, because the second battery terminal was "flying", not connected to anything.

if one or more elements that are part of the circuit are insulating, the circuit is "open" and the current does not circulate. as an example we take the battery first, but we touch the two terminals with a rubber glove on one of the hands. Now, the circuit has also joined the piece of rubber between the hand and the pole of the battery. the rubber is insulating, the circuit is open, the current does not pass and you survive.

there are not only conductive materials (such as metals) or insulating materials (such as rubber). There are countless intermediate cases. the ground is one of these. If the soil is wet, a bit of current makes it pass, if it is dry just not. fresh water is a bad conductor, sea water instead is a good conductor.

if one or more elements of a circuit are these "intermediate" materials, the amount of current flowing (and consequently the effects it generates, including the possible lightning) are directly proportional to their goodness as conductors. the other factor is the voltage of the generator: if the generator is 400 v, in order to have concrete effects, All circuit elements must be good conductors. if instead I have a generator of 10000 v (like that in electrified fences), although one or more elements are bad conductors (but not insulating), as in the case of wet soil, then I will still have an obvious effect.

ok I understood, I thought that the human body could act a bit as a condenser and place itself at a level of intermediate potential between the positive and the earth, and therefore have a minimum of flow of electrons during the process of "charging" of the capacitor, I pass the analogy. It is that I have also seen video in which the tipper of the truck touches the cable of the airline and discharges to the ground through the tires with great flow of flames and sparks.

It is that there are so many dear and intermediates so that I do not know if in the real practical case it should proceed with caution or with urgency, as perhaps the state of the patient would suggest.

 

[Fulvio Romano]

I also have two comments on electrical wires (I am an expert in accordance with the 11-27 code enabled under voltage bt on industrial equipment). I also attach an example of the tesla that explains how to intervene on a damaged car. If anyone comes to mind saying "ah see? if you need to explain it then the danger is there!" similar documents also exist for traditional and gas cars.

and so we arrived at the core of the question: what makes hybrid and electric vehicles so dangerous that circulate on our roads is their high voltage battery (if damaged in the accident).

First of all, if the car is so damaged that it has an electrical risk, the doctor cannot intervene before the firefighters intervened to free the occupants. not for risks related to the nature of the car but for the principle of incompenetrability of the bodies. and vdfs do courses on how to open cars, they are not tuna boxes.
in the annex then it explains well that the problem is when it is the circuit to be damaged, not the battery.

First due, quindi:

1. the first (just made), is that the incident must have compromised the integrity of the envelope of the high tesion battery, but accidents of this type are however many daily, every day. otherwise it should be honestly said that there are no other problems that are not the high cost of battery, their durability and disposal and environmental impact for their construction

"Anything, every day" smells a little bit like statistics. In any case we have said that according to tesla the break of the battery enclosure is the damage at the same time less dangerous and less likely, so as not to treat it even. Who do we want to believe? to tesla or to the anonymous?

define “high voltage” this type of batteries is not correct from an exquisitely electrotechnical point of view, so they are called in the automotive sector because they abundantly exceed 60 v dc, survival limit for those exposed.

the fact that 60vdc is lethal is all to prove. In this case I hypothesize that they have read the rules superficially and have considered the 50th limit for an alternating current, also valid for the continuous current, ignoring that:
a. physiological effect is different (fibrillation against blood dissociation)
b. the impedance of the human body changes to the change of frequency (although 1000 ohm is cautionary in any case)

we are talking about batteries capable of accumulating tensions of about 400 volts dc and delivering currents up to 125 ampères. you all know what happens if you put two fingers in the socket of your house, from which 220v (ac) and to the maximum 16 ampère!

Oh, my God! How do I comment on stuff like "taking tensions"? other straphalcions?
1. If I put two fingers in the socket, I lose two fingers. the probability of surviving is very wide because the current will hardly pass through the heart
2. I happen to have the alternating current here, so let's talk about it all the time.
3. in a voltage distribution set the current depends on the impedance of the circuit. What the fuck do you mean, 16a? If I put two fingers in the socket I get at most 450m, if I put a cable out much more than 16a unless the magnetothermic intervention.
You know what we're dealing with? ?

high voltage batteries for automotive use are then made of materials (lithium) that can be burned at contact with water.

What what? metal lithium in contact with water oxidizes with a violent exoergonic reaction. lithium ion batteries does not contain metal lithium. it would be like to say that as the metallic sodium in contact with the water explodes, put the salt in the paste is from bombers. Instead, lithium batteries can release hydrogen, this is the real danger, why don't we talk about it? danger obviously kept under control as by current legislation.

then we make an effort of imagination and answer these two simple questions:
what risks would the driver of an electric vehicle be exposed to?

Uh, an electric tram? Is the problem now the car or the tram?

what risks would anyone be exposed to extinguishing the fire of a gasoline car involved in a serious accident with an electric car?

the same dangers as those who find themselves extinguishing a fire in an electrical framework. Do you do it with water? It's a fessacchiotto and his department would be natural selection. water and foam should not be used for traditional vehicles. use powder or better still co2. Yes, I know it's more bulky.

it would be necessary to immediately recognize the electric car and prevent anyone from approaching and use only fire extinguisers to co2 or dust. then delimite the area, make sure of the electric risk and possibly cancel it in the technically most suitable way for that specific car (always that the environmental and meteorological conditions allow it)! Is that easy?

I don't see the differences with a traditional car. the same extinguishers, the delimitation must be carried out however, the type of vehicle must be identified also for other risks (e.g. cylinders), and the most suitable techniques are contained in the annex. I don't see the problem.

who then runs the danger of lightning?I don't know. the first rescuers! (the occupants of the incidental vehicle are considered - do not want it - “spendable”)
there are no odors or colations of liquid that can alarm, nor any other clue to notice if there are wires fed interrupted and uncovered, such as to generate a voltaic arc or lightning…
but if there was the break of the envelope of the high voltage battery its internal modules could be in short circuit with the body shop and so kill who comes in contact with the body shop.

Well... there's not even much fuel though. Have you thought about it? Do we try to calculate the fire load for a diesel car and an electric car?
Besides as explained by others before me, if I touch a cable discovered at 400vdc I bring myself to potential and with me the areola of picket around my feet. circulates current in my body? No, of course not.

 

[Fulvio Romano]

all the builders are then heading towards the “autonomous guide”, because it is the only way to avoid road accidents. the intention is however vain by the presence of a circular car park of technological level too heterogeneous

I don't accept this from robotics. the "autonomous driving" is developed because it is high technology as well as electric cars are high-tech cars. In addition, the current cost justifyes this investment. but does this really try to pass the concept that put us autonomous driving for fear of accidents? but then the honda legend is a car more dangerous than the fiat panda seen all radar systems, lane detectors, etc. that mounts?

have the European or Italian institutions produced adequate safety regulations? No! there is no specific regulation for the automotive sector and it is limited to general requirements borrowed from other operating areas. ask the Minister for Transport or the Transport Committee as a legal entity to regulate the subject.

The rules stipulate explicitly the management of electric vehicles, although they do not detail their construction. However electric trains, trams and trolleybuses exist and circulate on our roads for a long time, with similar issues and powers in play much higher. I would say that we can trust the existing rules, they seem to work.

in germany, where every vintage firmness only serves to hide their annaspare in the most total uncertainty, every single intervention “on the field” by the “specialist” charged by the manufacturer of the vehicle must be authorized by the employer in advance. this is already a download on the “specialist” every responsibility, but at least let it transpire of having intuited the delicacy of the matter

I leave the Campanian and comlottaro jargon, but for such a strong statement, references must be provided.

to those who were to object that aid to a gas or gasoline car heavily incidentata does also run great risks, I reply that from burnt or mutilated it survives, while from lightning you die and immediately, without having been previously alarmed by odours or liquids, as instead happens for cars equipped with combustion engines!

here you continue to speak erroneously of lightning in the continuous field, so I stop commenting. However I would like to understand all those deaths in Bologna what they owe. Didn't they smell? Didn't they know the autocysternaire was about to explode?

you can certainly develop alternative technologies such as those chemical chemicals, to obtain fuels and fuels (the two words are not synonymous) alternative to current ones to be used on vehicles at absolutely conventional.

I was convinced that lithium batteries were a chemical alternative. . .

meanwhile, the methane offers ecological scenarios and clearly lower dangerousness. but methane cars were not included in the eco-incentives plan to replace non-ecological cars, while electric and hybrid cars were.

Yes, the methane is definitely safer. In case of an accident you feel the smell and go away.

for private ones, such as the garage of a common home, know that the current charging time for a high voltage battery recharged by domestic electricity network is about 8 hours at 2300 watts, always that you don’t even have in operation refrigerator, air conditioner and washing machine, otherwise your 3-kw “high” home counter and you don’t charge a good deal!

extremely simplified scenario. Many houses have solar panels (cheeks, I know that the night is not the sun, but the enel gives you extra power to balance the day), there are more than 3kw meters and many install them even to keep on the air conditioning system, not for the electric car. if you are just bits then, there are charge controllers, part of the fridge and puff, the charging current decreases so as not to trigger the counter. It's not that it's Martian technology, eh, maybe put an extra hour to load.

this is however the least problem, because domestic electrical outlets are usually limited to a maximum load of 1500 watts. at 2300w for 8 consecutive hours the risk of fire of the garage tends to become a certainty...

But I'm sorry, but first he said 16th, which is equivalent to 3500w and now goes down to 1500w (7a)? But you think we're stupid? and don't pull out strange power factors, the batteries are remade, they look like a load almost purely resistive.

with the best compliments for vs. magazine, thanks for consideration and data space, but also the request to protect my privacy by omitting references to my identity, since (as you have understood) I am a professional in the field. .

No, definitely not so professional, especially if you're afraid to put your face on it.

the rest of the letter has political content that I do not want to analyze. I'm limited to the technical part.



p.a.
When I read 400v high voltage I get hives. up to 1500vdc we talk about low voltage, but vabbé, I can understand that here "high" does not belong to the technical jargon.

p.a.
a "discount" from continuous current is very different from that from alternating current. I do not want to enter the tedious details, but first of all in the worst case of arm-arm path the continuous current does not induce fibrillation, remains aware and the heart continues to beat. the greater damage is given by the dissociation of blood that if treated hyperbarically by many more chances of salvation than an untreated ventricular fibrillation. Moreover the release threshold from tetanization is 10ma for alternating current and 300ma for the continuous one.

p.a.
the annex is available here: https://www.tesla.com/sites/default/files/downloads/2014_model_s_emergency_response_guide_it.pdf

 

[Fulvio Romano]

apart from the mildly rude tone on which I prefer to fly over, it comforts me that even you say that a 400V battery and several current ampers does not constitute any danger, thank you.

Okay, that explains it to me. You tell me where I've been rude and nothing's wrong. If I deserve an admonition you give it to me, clear and justified, otherwise correct what you wrote, even because the fact that 400v is not dangerous I have not written it at all.

 

[exxon]

ok I understood, I thought that the human body could act a bit as a condenser and place itself at a level of intermediate potential between the positive and the earth, and therefore have a minimum of flow of electrons during the process of "charging" of the capacitor, I pass the analogy.

This happens, there is a capacitor charging, since any "free" conductor has its own intrinsic capacity towards the surrounding space (the simplification is passed). But when we go to see how much this capacity is and how much charge it moves, we realize that it is only instrumental values. In this case, the intensity of potential plays a fundamental role: when you take those annoying shocks from static electricity coming down from the car, these happen precisely for transfer of charge between two capacitors: the first is the car and the second is the man, but also in this case we talk of many thousands of volts to 400 v the transfer of charge would be rescible and would not even bother.

It is that I have also seen video in which the tipper of the truck touches the cable of the airline and discharges to the ground through the tires with great flow of flames and sparks.

this happens because, as mentioned above, the high voltage lines are always three phases and have potentials of tens or hundreds of thousands of volts compared to the ground. you can get an idea by looking at the length of the isolators that support the lines to the poles: If they are long a meter is because that is the distance that is considered safe before you have a discharge through the air. at 400 V, this distance could be quietly reduced less than a millimeter. in case you mentioned, the discharge does not cross the tires, but "high" them, passing from the circles to the ground because twenty centimeters are nothing for tensions of that intensity. as I wrote before, 400 v are stopped by a sheet of paper.

It is that there are so many dear and intermediates so that I do not know if in the real practical case it should proceed with caution or with urgency, as perhaps the state of the patient would suggest.

There are procedures and protocols that rescuers know very well. Many of the risks are unknown to the most, but the operators are trained to minimize their impact on general safety (just for example, the hook that descends from a helicopter should not be grasped at the flight from a man to the ground, because the helicopter can be electrostatically charged at such a level as to move it. . . ).

 

[Fulvio Romano]

at 400 V, this distance could be quietly reduced less than a millimeter.

I add, to understand, a spark of a millimeter in dry air requires a potential difference of 3000v.

when you "take the shock" because you took off the sweater actually the shock can be also 5000 / 6000v, but this thing should not confuse. the amount of charge (measured in coulomb) is so small that the current through the body lasts too little to do damage. (this is not true in the example of the exxon helicopter).

 

[exxon]

If you get an electrostatic discharge from a helicopter's winch cable, you'll stay there.

This risk, unknown to the most, is daily bread of those who go around with helicopters for oil platforms and accidents of this type are very rare. How come? procedures and protocols.

with electric cars will be the same: procedures and protocols (for rescuers), school-guided education and experience for street users. no one teaches you not to use the lighter to look if the tank of the car is full: you do not because it is logical not to do it. tomorrow no one will try if the battery of the electric car is charged using the language as it does with the remote battery for the same reason.

 

[IronMike87]

I ask you a question: who harmed the insulating of the positive conductor? If it has been hit by a metal part of the car, the battery is already short-circuited and you are perfectly safe from lightning, however you may need an extinguisher (as on current cars).

I might be wrong, but I really don't think that using a normal extinguisher to try to extinguish the combustion by battery pack is functional

 

[exxon]

here is an article that seems less sensationalistic and a little more technical.
risk of electric vehicles

 

[Fulvio Romano]

I might be wrong, but I really don't think that using a normal extinguisher to try to extinguish the combustion by battery pack is functional

co2 works nicely because the carbonic snow removes heat.
However I really can't understand the problem. intercepting and neutralizing a short circuit is the most trivial operation you can think of. just a component from a few euros. In this case there are more magnetothermics able to isolate the battery, plus the battery heat, plus the battery safety valves itself. How can one think that a short battery can be a serious risk of fire?

 

[IronMike87]

co2 works nicely because the carbonic snow removes heat.
However I really can't understand the problem. intercepting and neutralizing a short circuit is the most trivial operation you can think of. just a component from a few euros. In this case there are more magnetothermics able to isolate the battery, plus the battery heat, plus the battery safety valves itself. How can one think that a short battery can be a serious risk of fire?

I believe that in the case of thermal runaway it is not so simple the question. time ago I read a technical article, but at the moment I can't find it.

see if I can recover it from home pc

 

[Fulvio Romano]

I believe that in the case of thermal runaway it is not so simple the question. time ago I read a technical article, but at the moment I can't find it.

see if I can recover it from home pc

certainly if it goes in heat escape not. the extinguisher serves to break the triangle of fire, but if there is one that pumps energy there is little to do.
but how likely is a thermal runaway? in what conditions does it occur? if it is possible to intervene?
in the exxon link there are all these answers.

 

[cacciatorino]

Okay, that explains it to me. You tell me where I've been rude and nothing's wrong. If I deserve an admonition you give it to me, clear and justified, otherwise correct what you wrote, even because the fact that 400v is not dangerous I have not written it at all.

Sorry for the delay in the answer, but I was very busy.

I was referring to the slightly sarcastic tone with which you laughed at the doubts I had made after reading the article: "and up!"

There are no extremes for admonition, let alone, but surely I can make an idea of the character of the person facing a discussion in this way. In addition to this, I think this argument is totally counterproductive about the goal of conviving the interlocutor to share the point of view you are exposing: Have you ever thought that a no-vax mom could get into bursons after this apostrophes her in her usual ways? The only objective which will be to achieve will be the reorganization of their respective positions, (among other things, in the case of bureaucracies, I am doubtful that the purpose that is intended is not so much the diffusion of scientific culture as well as the satisfaction of one's own narcissism).

Back to the subject, the reading impressed me because in my spare time I volunteer rescuer in one of the many "crosses" that are in Italy, so I could really deal with the incidental electric car.
from a systemic point of view, I think that wherever there is potential energy there is automatically danger (an inflammable liquid tank, a suspended load, a compressed spring) and it seems strange that in the case of the battery this is not, despite the high energy density, that is why I try to convince myself otherwise.

 

[cacciatorino]

I can't find the exact point where it was written, but we can't take the tesla as reliable when it says that the electric car is safe, that should make it a certified body that isn't part of it.

regarding the thermal runaway seems to me that the boeing had a sea of problems on the first 737 delivered to customers, who were stopped on the ground for a long time before they understood why the batteries burned. If they have problems in the spacecraft field, I imagine they may be in the automotive field, where safety standards are much more blatant.

We'll see, it's definitely an extra problem to take into account.

 

[exxon]

I have already given: a methane car exploded to me less than 5 meters away.

I'm still here because, for a joke of fate, the gas didn't burn. the tank was in the back trunk of a two volumes that traveled ahead to me and parked on the side. the driver came down and I passed over when the deflagration came from behind. the back seat of the car to gpl was expelled through the front windscreen (which took off), flying over my car and landing ten meters ahead of me.

the smell of gas was impressive, a sign that the mixture had the concentration to be burned. At a distance of many years I wonder how in the rubbing of plates, glass, seat springs and asphalt, no spark has been produced.

I always wondered what would happen if the driver was still sitting in his place: things that are better not to think.

Here, after this adventure... the batteries of electric cars can also try them with the language: They don't scare me anymore!

p.s. the next day I went to see the car (which was under kidnapping at a coach I knew): the cylinder was very small, and the only visible damage was a tiny five centimeters long slot, opened less than two millimeters in the wider part. explosive for overpressure.

 

[Fulvio Romano]

I was referring to the slightly sarcastic tone with which you laughed at the doubts I had made after reading the article: "and up!"

I would not confuse sarcasm with education. I am sarcastic, yes, it is a part of my character that I do not think I have to change. I don't think I'm rude, it's two different things.

There are no extremes for admonition, let alone, but surely I can make an idea of the character of the person facing a discussion in this way. In addition to this, I think this argument is totally counterproductive about the goal of conviving the interlocutor to share the point of view you are exposing: Have you ever thought that a no-vax mom could get into bursons after this apostrophes her in her usual ways? The only objective which will be to achieve will be the reorganization of their respective positions, (among other things, in the case of bureaucracies, I am doubtful that the purpose that is intended is not so much the diffusion of scientific culture as well as the satisfaction of one's own narcissism).

after 11 years and almost 4000 posts I honestly didn't think you needed to "get an idea" my character. In any case, yours is a point of view far from mine. I think his shock therapy is the only way to deal with pro-epidemies (no-vax is a term that does not make the idea). and if you look at statistics there are many more "converted" with this method than with a more blande and tolerant methodologies. to say it with four-eyed walter, the echo chamber must be demolished, not influenced.
are just different points of view, only that the statistics follow my, at least for now. are dynamics that change very quickly.

 

[cacciatorino]

I would not confuse sarcasm with education. I am sarcastic, yes, it is a part of my character that I do not think I have to change. I don't think I'm rude, it's two different things.


.

Do you think giving mouthpieces in public to another forum user is polite behavior? You didn't use these terms but the thought you had in your head was that.
In my opinion, using sarcasm by rubbing the reactions that can be caused in the victim of sarcasm itself is a rude behaviour, cmq you are free to think otherwise.