UKC

/ Electric cars and safety

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The Lemming - on 05 Feb 2018

I'm after a bit of background advice or information from people who actually know rather than listening to hearsay or rumours on the internet. How safe or dangerous are electric cars  that have been involved in an accident or crash?

Do the electrics, especially the batteries cause any threats to safety if damaged?

I'm trying to build up a bit of research rather than from opinion based on rumour.

Post edited at 08:10
3
BnB - on 05 Feb 2018
In reply to The Lemming:

> I'm trying to build up a bit of research rather than from opinion based on rumour.

So you focused your research on a climbing forum.

plyometrics - on 05 Feb 2018
In reply to BnB:

The likely outcome of researching on here will most likely conclude any threats will be caused by all, or one of, the following:

Brexit

Dry Tooling

Jacob Rees-Mogg

God

Tick Marks

I look forward to seeing the results.

 

 

The Lemming - on 05 Feb 2018
In reply to BnB:

> So you focused your research on a climbing forum.


Yes!

Is that so hard to fathom?

This site probably has the widest spectrum of skills and knowledge than any other forum on the internet by the very fact that climbers come from just about all areas of the working world.

This is a genuine question and I'd appreciate some helpful comments.  That is not too much to ask for, is it?

12
wercat on 05 Feb 2018
In reply to The Lemming:

I do know that apart from the very high currents that can flow in damaged Lithium Ion cell arrays, causing great heat, the electrolyte, unlike the majority of other cell technologies, is organic and inflammable.  I was reading a document about this the other day

http://www.sfpe.org/page/2012_Q4_2

 

[courtesy wercat Useless Information Mining Corp]

ps - in the case of the C5 the other hazard is of course looking funny

Post edited at 09:27
jkarran - on 05 Feb 2018
In reply to The Lemming:

> Do the electrics, especially the batteries cause any threats to safety if damaged?

Yes. They pose an electrocution risk if non-isolated parts are exposed during an accident or rescue. They pose a fire risk if the packs are damaged. The risks are in some ways different to vehicles powered by other energy stores but in others fundamentally similar, there's a lot of stored energy which can be released in an accident. As with other energy stores the risks are considered and mitigated during design.

jk

jezb1 - on 05 Feb 2018
In reply to The Lemming:

Register on PistonHeads.

timjones - on 05 Feb 2018
In reply to The Lemming:

> Yes!

> Is that so hard to fathom?

> This site probably has the widest spectrum of skills and knowledge than any other forum on the internet by the very fact that climbers come from just about all areas of the working world.

So do gardeners, have you tried asking here ;)

http://www.gardenersworld.com/forum/

 

paul__in_sheffield - on 05 Feb 2018
In reply to The Lemming:

600V DC link can also deliver life threatening current if compromised.

Impact damage to the battery cells can potentially be explosive if it allow the ingress of air.

The batteries will make any fire very difficult to put out.

This all assumes Lithium batteries. Some other solutions which I've worked with such as molten sodium-sulphur have similar issues post-impact, especially with water ingress.

Hydogen fuel cell gas tends to be in shaped carbon fibre  containment which has shown itself to be remarkably robust. There has also been some work on carbon nano-tube containment which has positive safety implications. Hydrogen doesn't hang around in outdoors applications, and tends to dissipate extremely quickly so you have to be unlucky to get an explosion, however a compromised DC system can provide that bad luck (you still need some level of battery or supercap transient energy storage to complement the fuel cells). Supercaps can give you lovely fat sparks!

Paul

Ex Poster 666 on 05 Feb 2018
In reply to The Lemming:

The batteries have sufficient energy to shift a tonne of metal at 90 mph, imagine what can they do to a bag of water like yourself?

Jamie Wakeham - on 05 Feb 2018
In reply to The Lemming:

The Prius has been on the roads for two decades now.  If there was a significant risk from the batteries we'd have spotted it by now (see also: Won't the batteries wear out after a couple of years?)

I'm more concerned about driving around sitting on a 50 litre tank filled with petrol!

jkarran - on 05 Feb 2018
In reply to paul__in_sheffield:

> Hydogen fuel cell gas tends to be in shaped carbon fibre  containment which has shown itself to be remarkably robust. There has also been some work on carbon nano-tube containment which has positive safety implications.

Any idea why carbon? I thought aluminium overwound with glass or aramid was the normal choice for composite pressure vessels? I guess the stiffness of carbon becomes useful as you move away from simple, basically self supporting spherical/cylindrical forms?

jk

paul__in_sheffield - on 05 Feb 2018
In reply to jkarran:

There are currently a lot of shape compromises to be made wrt chassis and battery pack shape which often precludes standard pressure vessel configurations.

The Lemming - on 05 Feb 2018
In reply to paul__in_sheffield:

> 600V DC link can also deliver life threatening current if compromised.

 

Its this bit that I am especially concerned about.  I've done a bit of googling and read accounts of First Responders of various countries going to traffic accidents with electric cars, touching those cars and being instantly electrocuted.

 

Is this all hyped up, down right myth, lies, scare mongering or a real and present danger when confronted with a electric car involved in an accident?

Post edited at 12:22
wercat on 05 Feb 2018
In reply to Jamie Wakeham:

One thing we heard on a trip to Germany a year or so ago was that the German Fire Brigade have become very cautious about fires in homes using solar power.   One news report while we were there said that they would leave the homes to burn themselves out rather than take risks with the batteries still active.

This sounds analagous to the risks to occupants and rescuers in car crashes involving electric power

Ex Poster 666 on 05 Feb 2018
In reply to wercat:

And the panels still generating (during the day!)

They don't like electricity, firemen, and dangling cables. I was rescued from a house fire and the first thing they did after breaking in was killing the power at the CU.

Post edited at 12:43
David Riley - on 05 Feb 2018
In reply to The Lemming:

>  touching those cars and being instantly electrocuted.

Unlikely unless you went out of your way to hold onto protruding wires with each hand. You watch out for hot bits with a normal engine.

I am happy to touch either side of 240V mains as long as not in contact with anything else.

2
The Lemming - on 05 Feb 2018
In reply to David Riley:

 I am happy to touch either side of 240V mains as long as not in contact with anything else.

 

Would you be happy to hold AC current or DC current?

My understanding is that electric cars are DC current.  I am interested to learn and research this project for my own development and safety.

 

David Riley - on 05 Feb 2018
In reply to The Lemming:

Makes no difference. No current flows unless you have two connections. Although one of them might be the ground. On its wheels a car is isolated from ground so that cannot be one of the two connections.

1
Philip on 05 Feb 2018
In reply to The Lemming:

https://en.wikipedia.org/wiki/Plug-in_electric_vehicle_fire_incidents

Start reading this. Then you need to juggle the risk of electric cars vs the alternative? If you're buying a new electric car, the simple act of buying a new car may increase your safety.

But then you may be a total idiot, run out of charge in Peaks and get eaten by the residents of Royston Vasey.

Bob Kemp - on 05 Feb 2018
In reply to BnB:

> So you focused your research on a climbing forum.

The forum that says "General non-climbing discussion'. What's the problem?

 

2
Bob Kemp - on 05 Feb 2018
In reply to plyometrics:

> The likely outcome of researching on here will most likely conclude any threats will be caused by all, or one of, the following:

> Jacob Rees-Mogg

And why not? An in-situ Rees-Mogg may well explode on contact with foreign vehicles. Are the risks greater with electric cars?

 

Bob Kemp - on 05 Feb 2018
In reply to The Lemming:

You'll probably find this useful - 

https://www.sciencedaily.com/releases/2017/05/170508083558.htm

 

jkarran - on 05 Feb 2018
In reply to David Riley:

> I am happy to touch either side of 240V mains as long as not in contact with anything else.

Really? That's not a very good idea, suggesting it is safe is downright reckless.

Lemming: I couldn't say whether the stories you've heard are myth, lies or whole honest truth. The battery packs in cars are easily capable of delivering lethal shocks, basic pack voltages are in the low hundreds of volts, often boosted up into the high hundreds in normal operation for efficiency. Unlike 'mains' electricity the pack isn't earth referenced so in some respects it's safer or at least harder to get a shock, it's fully isolated in normal use from earth and chassis (local earth) and you need access to both terminals or at least two nodes at significantly different voltage to get a shock. If it's seriously disrupted, full of water or foam and there are live wires/bus-bars exposed all bets are off, that thing could kill you in an instant. If it's neatly contained by design, the vehicle has detected the crash, shut down and opened the isolators disconnecting and splitting the pack up into safer (not safe) units then it's very hard to believe they're routinely killing firemen. It's like the difference in risk between a car scraped along the armco with the airbags blown and a stunned driver stood by it vs one skewered upside down in a tree with 80L of petrol splashed all over the scene and the engine still running flat out. One is likely to do you little harm, the other is extremely dangerous.

If you're worried about it from a work perspective request training!

jk

1
paul__in_sheffield - on 05 Feb 2018
In reply to The Lemming:

> Its this bit that I am especially concerned about.  I've done a bit of googling and read accounts of First Responders of various countries going to traffic accidents with electric cars, touching those cars and being instantly electrocuted.

> Is this all hyped up, down right myth, lies, scare mongering or a real and present danger when confronted with a electric car involved in an accident?

Interesting one this. My first exposure to EV research in the early ‘90s was based around 42V systems, which was absolutely the highest voltage allowed for use on the roads. We were doing integrated starter/flywheels as torque boost for downsized engines on trucks. Obviously at this voltage, currents were eye watering, and hence the size of cables etc. The lid to high voltage was lifted around 10 years later.

specialised training is required for anyone performing vehicle servicing , not just emergency services. The last development I was involved with was an all electric Evora demonstrator for Lotus running a 600V DC link. We were forced to fit a very obvious circuit breaker on the outside of the body in order to get road test approval. I would think this would be an obvious feature, but not one I’ve seen on EVs and HEVs I’ve driven.

David Riley - on 05 Feb 2018
In reply to jkarran:

I didn't suggest it was safe. I'm sure many on here are happy to hang by one hand over a 30m crag.

1
jkarran - on 05 Feb 2018
In reply to David Riley:

> I didn't suggest it was safe.

You said without meaningful further explanation you were happy to do something which could very easily get someone killed should they take you at your word. Not clever.

 

2
Bogwalloper - on 05 Feb 2018
In reply to The Lemming:

I'm glad you have started to get some sensible answers and started an interesting discusion after the first two clever-dick answers.

W

1
David Riley - on 05 Feb 2018
In reply to jkarran:

That's just silly. So if I say I am happy to hang on one hand over High Tor. You would say "Really? That's not a very good idea, suggesting it is safe is downright reckless." ?

1
jkarran - on 05 Feb 2018
In reply to David Riley:

> That's just silly. So if I say I am happy to hang on one hand over High Tor. You would say "Really? That's not a very good idea, suggesting it is safe is downright reckless." ?

I'd expect on a climbing forum people might reasonably be expected to understand the risk posed by pulling stunts on High Tor, frankly anyone with eyes and common sense could.

On a thread about electrical safety suggesting to someone asking elementary questions you'd be happy to touch live mains wiring without explaining *exactly* how, when and the risks that remain unmitigated is reckless.

jk

Post edited at 14:56
1
David Riley - on 05 Feb 2018
In reply to jkarran:

Don't try this at home kids.

David Barlow - on 05 Feb 2018

Read the Prius emergency responders guide,  which has specific guidance about the electricity supply.

https://techinfo.toyota.com/techInfoPortal/staticcontent/en/techinfo/html/prelogin/docs/1stprius.pdf 

Post edited at 15:49
DancingOnRock - on 05 Feb 2018
In reply to David Barlow:

Quite. 

The batteries consist of several separate 7.2v modules. The whole battery is sealed inside a metal container. 

People a lot cleverer than the UKClimbing bodgit and legit massif have been thinking about this for years. 

deepsoup - on 05 Feb 2018
In reply to Philip:

Peak.

(Well, to be fair, maybe the locals do say 'Peaks' in Royston Vasey.)

;-)

FactorXXX - on 05 Feb 2018
In reply to The Lemming:

One of them tried to kill Richard Hammond.
Whether that's a bad thing or not is another matter...

Toerag - on 05 Feb 2018
In reply to The Lemming:

There's a thread on facebook showing video of a Tesla embedded in armco outside an Austrian tunnel burning like a good-un (google "tesla fire austria"). The on-video commentary said there's two links for the battery which the firebrigade can access and cut to disable it, footage showed them going in with a disc cutter just in front of the left rear wheel to do it. The car was quarantined for 2 days in case it started burning again.

I don't think there's much difference if an EV is on fire or a fossil-fuelled one - the car's going to be a write off, and you're going to be burnt to death before it's put out if you're unconcscious and can't get yourself out in either situation.

wercat on 05 Feb 2018
In reply to Toerag:

Probably best to put it out of mind, as I suppose did the Me 163 pilots, for whom the hazard existed, after a flight at exhilarating speed, of any unused fuel entering the cockpit on crash landing and dissolving him or her.


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