Hybrid vehicle myths and firefighter rescue

[firefighterMV]

I posted similar topic in extrication, but wanted to get the best exposure to this topic. I want to bring a couple ideas to the table about hybrid myths I've recently learned about. I want others' opinions and if it has been explained to anyone else the same way. I was at a conference this past weekend and a representative from a company called MGS Tech. did a shortened (1hr.) class on clearing up myths on hybrid technology vehicles (as well as alternative fuel vehicles). He basically stated that it is okay to cut the orange, high voltage cable if necessary. The way it was explained was that if you cut this cable the low amperage main fuse or breaker will instantly trip and the high voltage will be isolated. He stressed the importance of amperage over voltage and gave the example of your clothing with static electricity has thousands of volts of electricity but cannot overcome the body's resistance. He said it was completely safe to use any tools (bolt cutters, hydraulics). Any thoughts on this? I have a lot more information that he presented too if anyone is interested. Oh and this guy is a 20 year veteran engineer involved in hybrid production from the very start and a certified master tech. with Toyota. (All hybrid technology is Toyota patented, other manufacturers buy the permissions for this technology to be put in their vehicles.) Sorry this was so long winded. Very important since it contradicts everything most of us have ever been taught.

[michfire]

Thanks for sharing the info.

IHe basically stated that it is okay to cut the orange, high voltage cable if necessary. The way it was explained was that if you cut this cable the low amperage main fuse or breaker will instantly trip and the high voltage will be isolated.

Oh and this guy is a *** 20 YEAR VETERAN ENGINEER***involved in hybrid production from the very start and a certified master tech. with Toyota.

As a simple layman who has dealt a lot with engineers of varying disciplines, what I bolded made me nervous. I don't want an engineer to tell me it works, I want an engineer who has felt comfortable enough to cut the cable himself! Then if it doesn't work, well, then we have one less of them out there. Next theory can be tested by a lawyer. Then a democrat, and so on... (just poking fun)

I haven't gotten too personal with hybrid vehicles yet. If they are all made by Toyota, are they generally the same from car to car? If so, how practical is it to pull the main fuse you were referring to? Or, does anybody have experience in disabling one of these things?

[ryguy1]

Thanks for sharing the info.



As a simple layman who has dealt a lot with engineers of varying disciplines, what I bolded made me nervous. I don't want an engineer to tell me it works, I want an engineer who has felt comfortable enough to cut the cable himself! Then if it doesn't work, well, then we have one less of them out there. Next theory can be tested by a lawyer. Then a democrat, and so on... (just poking fun)

I haven't gotten too personal with hybrid vehicles yet. If they are all made by Toyota, are they generally the same from car to car? If so, how practical is it to pull the main fuse you were referring to? Or, does anybody have experience in disabling one of these things?

i tend to agree with this. i wouldn't feel comfortable cutting the line on his say so. i would like to see him do it. after all, everything works in theory.... but i don't really know all that much about it so maybe thats just ignorance talking. i would be interested about how you can pull the fuse and cut the power that way.


here is another interesting one. we had a single car roll-over the other day. the driver got out before we got there so no extrication. when the car was righted and we poped the hood, we found it was a LNG car. there was nothing on the exterior of the car to indicate this. anybody else run across this, and is there any thing special you do?

[SFDE37]

Try this link regarding CNG:

http://www.firetrainingresources.net...ressedpics.pdf

[sklump]

I am work on GM trucks, yes the circuits are protected. Why would ever cut these cables and would you trust the interuptor to work. Would you cut your wires in your house they are also protected?

[MalahatTwo7]

There is something about the large black text that runs along some of those red/orange heavy cables, or is attached as a tag that reads something like:


DANGER! HIGH VOTLAGE! DO NOT CUT!


Or words to that effect. The Navy taught me all about high voltage lines and what NOT to cut through when doing damage control runs.

When a "Certified Engineer" puts his words to practice and can tell me all about it, then I'll consider but not until then. I'll even hand him the bolt cutters and then stand by at a safe distance with a long wooden pole to push his frizzed out body away from the car so that we can hook him up to the AED.

[firefighterMV]

I am work on GM trucks, yes the circuits are protected. Why would ever cut these cables and would you trust the interuptor to work. Would you cut your wires in your house they are also protected?

The only difference with the wires in your house is they are AC, not DC. And actually there are AC versions in some of these hybrids, but the difference again being they are not grounded. These high voltage systems are completely isolated...that being the reason that it is accepted to enter standing water with a submersed hybrid (no ground to body of the car). But I understand the concerns, believe me! I certainly am not going to be teaching this method or trying it myself without some more backing on the issue. I just thought it was an interesting approach and new information. And to answer some of your questions...yes he has cut them in classes on vehicles to show that this is okay. He just had a about a fifth of the time with our class than he normally spends on the subject.

[The nots so new FNG]

I'd caution any one reading this to be careful if you find these high voltage cables damaged. Different vehicles have different voltages and capacities. The Escape for instance is a 300V system. The Prius is about a third of that. Both are more than enough to hurt you. The AH rating is actually quite low on these cars. The Prius is only a 6Ah rating. The hybrid buses on the other hand are a lot worse. They have dual 360V-65Ah packs.

I AM and engineer and even a Electrical one at that. I don't trust the interupters 100%. Just like you don't trust the breakers in fuse panel that's been damaged. They probably work but you never can be quite sure. Remember, that vehicle was in an accident and you are relying on the engineers to think of every possible way that battery box could have been impacted.

[fyrmnk]

We have access to the emergency response guides for quite a few different hybrids. Since Toyota was mentioned, I looked at the one for the Highlander that was issued in 2006. In the high voltage section it has the following warning: "High voltage electricity can cause death or serious injury from severe burns or electric shock. To avoid death or serious injury wait 5 minutes after disabling the vehicle to discharge high voltage electricity, and do not touch, cut, or open any orange high voltage power cable or high voltage compartment."

Was the engineer talking on the authority of the manufacturers or just in his opinion? Might try calling Toyota and seeing if they agree with him. The training we went to as well as the ERGs we have from the manufacturers themselves advise against it.

Look forward to finding out any new info out there.

[ScareCrow57]

Found this interesting article Hybrid Safety Concerns

Also, water does not conduct electricity. The impurities in the water is what conducts the electricity, hence salt water is a better conductor. Pure distilled water will not conduct electricity.

I’ve grabbed 110 vac and that tingles. 220 vac hurts, and 440 vac will send you across the room and into next week. I’ve never grabbed the latter, but know people who have. I’ve also had the pleasure of grabbing 12 vdc and 48 vdc. 12 does nothing, 48 gets your attention.

The hybrids can have as much as 650 volts (unknown if it is dc or ac), that voltage will hurt. Of course, that assumes you complete the circuit. There are people who work on high voltage lines with bare hands from a helicopter. They can do this because they are only working on one side at a time, that is, they never complete the circuit.

The real issue is this

"You need to know where those wires are, and the high-voltage equipment," Honda's Almeida said. ..

Almeida says hybrids pose no additional danger as long as the rescue procedures outlined in their manuals are followed, starting with ensuring the ignition is shut off and the key removed, which is standard procedure for responders to conventional cars.

We don’t usually have time to find the manufacturers procedures on scene, and I’m sure each one is different.

[FireWA1]

If I remember my physics correctly here is a good law to look at is Ohm's Law (V=IR).

V=IR V=Voltage I=Current (amperage) R=Resistance

So, you can have an extremely high voltage along with a very small amperage as long as there is a resistance that is very high.

SO yes, High Voltage is most often then not very dangerous and you want to stay away from it. There can be situations where you can have trillions of voltz going though your body and it wont kill you. Also low voltage can be hazardous.

Here is OSHA's little deal with electricity.
http://www.osha.gov/SLTC/etools/cons...eccurrent.html

[ScareCrow57]

If I remember my physics correctly here is a good law to look at is Ohm's Law (V=IR).

V=IR V=Voltage I=Current (amperage) R=Resistance

So, you can have an extremely high voltage along with a very small amperage as long as there is a resistance that is very high.

SO yes, High Voltage is most often then not very dangerous and you want to stay away from it. There can be situations where you can have trillions of voltz going though your body and it wont kill you. Also low voltage can be hazardous.

Here is OSHA's little deal with electricity.
http://www.osha.gov/SLTC/etools/cons...eccurrent.html

Actually, it would be the power, aka Wattage.

Watts = Amps X Volts = Amps X Resistance Squared.

[LEWTFL]

If I may here are one or two other points to ponder.

Firstly in the equations of power and voltage bear in mind that the situations in question you are "R", the resistance. What is your R value? If you are in the megohm range you may be quite safe. If you're down in the low kilohm area you may be more of a conductor than an insulator.

Secondly AC or DC current flow doesn't really matter. It is current flow and it hurts. Current, either AC or DC, through a resistance, you or another conductor will cause some heating depending upon the resistance value. What was your R value again? Heating of a wire conductor makes a hot wire. Heating of you makes for dead tissue, and, possibly an interruption of coronary function.

Thirdly I have been "bitten" by 120 volt AC, 240 volt AC and 440 volt AC. The latter was at 400 Hertz and did throw me across the room.

I can also feel a slight tingle off of battery banks while cleaning or taking specific gravities.

A long time back I was taught that if you ever find yourself cutting into live circuits, don't stop cutting. Just keep going and get through them as quickly as possible and close your eyes, because there is a flash coming.

My point is that you may cut through high voltage hybrid vehicle cables and nothing bad will happen, but if you aren't so lucky you might get killed and you'll never see it coming. It's your choice.

[ScareCrow57]

If I may here are one or two other points to ponder.

Firstly in the equations of power and voltage bear in mind that the situations in question you are "R", the resistance. What is your R value? If you are in the megohm range you may be quite safe. If you're down in the low kilohm area you may be more of a conductor than an insulator.

Secondly AC or DC current flow doesn't really matter. It is current flow and it hurts. Current, either AC or DC, through a resistance, you or another conductor will cause some heating depending upon the resistance value. What was your R value again? Heating of a wire conductor makes a hot wire. Heating of you makes for dead tissue, and, possibly an interruption of coronary function.

Thirdly I have been "bitten" by 120 volt AC, 240 volt AC and 440 volt AC. The latter was at 400 Hertz and did throw me across the room.

I can also feel a slight tingle off of battery banks while cleaning or taking specific gravities.

A long time back I was taught that if you ever find yourself cutting into live circuits, don't stop cutting. Just keep going and get through them as quickly as possible and close your eyes, because there is a flash coming.

My point is that you may cut through high voltage hybrid vehicle cables and nothing bad will happen, but if you aren't so lucky you might get killed and you'll never see it coming. It's your choice.

Actually, AC vs DC does matter. You have to also consider things like capacitance, inductance, along with resistance. Also, DC voltage may not always flow as there could be things like diodes and such in the path. And then you have to consider ionization as well. The bottom line is, know your enemy. Treat electricity with respect. And if you don't know what you are doing when dealing with it, don't.

[LEWTFL]

In some ways AC vs. DC may matter, however when it's arcing and sparking in front of you it really doesn't enter into the picture.

[RFDACM02]

One thing to remember is that if we're cutting on a vehicle, all bets are off as to the purported safety systems. We cannot trust that a wire still has it's ground, or remains properly connected to its fuse/trip protection. Accidents cause lots of metal and plastics to move severing wires, destroying fuses, shorting systems, leaking fluids, and on and on.

I'd ask the 20 year hybrid engineer to drop a car 50 feet to the pavement and tell me what I can trust and what I can't, maybe he'd understand our dilemma.

[The nots so new FNG]

I'd ask the 20 year hybrid engineer to drop a car 50 feet to the pavement and tell me what I can trust and what I can't, maybe he'd understand our dilemma.

Believe it or not, they do try to replicate this situations and design systems to protect you. The problem is nothing is 100% ever. Humans have to envision the failures.

During extrication, we do horrendous things to the structure of the vehicle. We cut places that designers never thought we would and you'll find air bag cylinders. It is quite possible we may cut somewhere that the designers never intended on a hybrid as well.

The moral is to know the enemy, do a good size up and work from that. A hybrid into a tree is likely within design specs. A crushed and rolled hybrid from a freeway collision where the vehicle is separating might be a very different matter.

[KB1OEV]

Actually, it would be the power, aka Wattage.

Watts = Amps X Volts = Amps X Resistance Squared.

You have the second formula a bit backwards.

P = E*I
Power equals voltage x current

P = (I^2)*R
Power equals current squared x resistance

P = Power (Watts)
I = Current (Amps)
E = Potential (Volts)
R = Resistance (Ohms)


That OSHA articla could do with some rewording; "the voltage of the current" doesn't give you the feeling they know what they are talking about.

[ScareCrow57]

You have the second formula a bit backwards.

P = E*I
Power equals voltage x current

P = (I^2)*R
Power equals current squared x resistance

P = Power (Watts)
I = Current (Amps)
E = Potential (Volts)
R = Resistance (Ohms)


That OSHA articla could do with some rewording; "the voltage of the current" doesn't give you the feeling they know what they are talking about.

Good catch, that damn dyslexia will get you every time. I use a little phrase too Twinkle Twinkle little star, power equals I squared R.

[nmfire]

That OSHA articla could do with some rewording; "the voltage of the current" doesn't give you the feeling they know what they are talking about.