Safety of battery packs in electric vehicles during collisions

peter67 · Guru

Safety of battery packs in electric vehicles during collisions

Bicyclecamper · Guru

When, I was a Firey, every accident we attended, no matter how bad, we did out best to disconnect the battery, as it is the battery first , then fuel second that starts a fire. Not always possible or safe to disconnect the battery, but even so, their was always a fire fighter, with a hose, primed , and ready to go, on the engine and battery compartment. Out of the 27 accidents that I attended, only 4 burst into flames, and they were 1 fuel related and 3 battery related fires. One thing, nigh on impossible to put out when they have ignited are aluminium engines and wheels. You think, they are out but they constantly re-ignite.

-- Edited by Bicyclecamper on Thursday 4th of March 2021 03:38:09 PM

-- Edited by Bicyclecamper on Thursday 4th of March 2021 03:42:39 PM

erad · Guru

Peter67: There is a possibility that the car will catch fire die to the battery pack shorting out. It is unlikely that you would be electrocuted by touching the car because the car would earth through the tyres. However, we are talking here about 800 volts of batteries in a Tesla, so you would have to be careful, but I would not expect it to be too dangerous. Now, if the battery pack did decide to short out whilst you were in or near the car, well then I would stand well back because there is a fearful amount of energy stored in the batteries. A 12 V battery is bad enough, but 800 volts? Wow!

Jaahn · Guru

peter67 wrote:
I was wondering if anyone here could tell me how much energy is typically stored in an suv battery pack, their construction and propensity to burn or suddenly discharge when damaged after the vehicle has suffered significant damage in an accident. Is there a possibility the car could become "live" or perhaps it's towed to a panel shop and poses problems for repairers there?

Hi Peter smile

I like to think of the danger like this. hmm

Yes there is a risk and having a serious accident increases the chances. But the manufacturers know the risks better than you and i and do testing and crashes etc to quantify the risks. And procedures are published in the rescue and repair fields to handle the risks. I am happy with all that. After all for the past 50 years we have been driving around with up to 100 ltrs of very volatile high octane fuel suspended underneath and in later years only plastic tanks and fuel lines, and how many problems were actually caused by that fuel compared to the Kms travelled. Insignificient numbers !! So I am happy to drive new cars whatever the technology !

Jaahn

-- Edited by Jaahn on Thursday 4th of March 2021 06:05:03 PM

oldbloke · Guru

Bicyclecamper wrote:
When, I was a Firey, every accident we attended, no matter how bad, we did out best to disconnect the battery, as it is the battery first , then fuel second that starts a fire. Not always possible or safe to disconnect the battery, but even so, their was always a fire fighter, with a hose, primed , and ready to go, on the engine and battery compartment. Out of the 27 accidents that I attended, only 4 burst into flames, and they were 1 fuel related and 3 battery related fires. One thing, nigh on impossible to put out when they have ignited are aluminium engines and wheels. You think, they are out but they constantly re-ignite.

-- Edited by Bicyclecamper on Thursday 4th of March 2021 03:38:09 PM

-- Edited by Bicyclecamper on Thursday 4th of March 2021 03:42:39 PM

Yep, believe it or not,,,it has been used in some solid rocket fuels. Burns really great.

Pommies found that out when the ally ships went up in flames fighting over the Forlkland Is.

City of Melbourne and a few others when the cladding on some of the building went up in flames. (Ally and Styrofoam/plastic) you gotta be joking. Unfortunately the ones who died aren't laughing. What's astounding is its a very well known fact it burns really good esp if a little mag is added.

The world is full of greedy idiots

Aus-Kiwi · Guru

Not just accidents ! The batteries grow little spikes in them , they can
Short out themselves too ! Tesla is having issues with their batteries right now !!

rgren2 · Guru

car would earth through the tyres.

No, tyres are insulators.

Peter_n_Margaret · Guru

rgren2 wrote:
No, tyres are insulators.

Tyres are full of carbon black. They are VERY poor insulators. Any high potential would flow through them.

Cheers,

Peter

rgren2 · Guru

Ill remember that next time I get a static shock.

KFT · Guru

rgren2 wrote:
Ill remember that next time I get a static shock.

That is most likely you discharging through the vehicle rather than the other way around.

Aus-Kiwi · Guru

The earth to ground has nothing to do with it ! The batteries are shorting ir the loom is shorting on its own . Voltages are still low even with DC .. 330,000V transmission just blows the tyres ! Fortunately theres good earth faults on transmission network !!!

rgren2 · Guru

KFT wrote:
rgren2 wrote:
Ill remember that next time I get a static shock.
That is most likely you discharging through the vehicle rather than the other way around.

Woo hoo, Im a shocking person.

Greg 1 · Guru

Quite a few incidences in the US of Tesla's catching fire following an accident. Towie's don't like them as some have caught fire on the tilt tray taking the truck with it. Welcome to the new world.

oldbloke · Guru

Some types of batteries have a habit of igniting spontaneously. Been banned on aircraft for years. Lithium i think.

peter67 · Guru

Thank you for the replies all. A friend is looking for a small hybrid car/shopping trolley so that is why I asked the question. My only experience is with lipo batteries, a friend left one on a top quality balance charger in his under ground garage, and burnt the whole house down. I've also seen a large lipo battery start swelling with a little smoke so it was dumped in a bucket of cold water. A half hour later they took it out and it started smoking again. Cheers

Edit, old bloke I read an article some time back where the Boeing Aircraft Company acknowledged that the huge battery packs in their aircraft could not be extinguished if they caught fire, so they are enclosed in a special container inside the aircraft and vented to the aircraft exterior via a large pipe. If it caught fire in flight I'm thinking the 800kph slip stream would lead to charring of the aluminium aircraft skin, at the very least.

-- Edited by peter67 on Sunday 7th of March 2021 06:20:50 PM

Peter_n_Margaret · Guru

oldbloke wrote:
Some types of batteries have a habit of igniting spontaneously. Been banned on aircraft for years. Lithium i think.

Banned for years? Oh come on! One fire, or was it 2? Deaths, Nil.

These are batteries that are nothing like those used in cars. MUCH higher power density and different chemistry entirely. There are 5 different common lithium battery chemistries. The ones we use in RVs and in cars (LiFeO4) are the safest of all 5 and probably safer than lead acid batteries we have used for years because they produce hydrogen. The much higher power does require respect.

But don't let a good story get in the way of the facts.

Anything new of different will be a problem for some people. They will want someone walking in front of electric cars with fed flags next. Now there is a new idea. blankstare

Cheers,

Peter

oldbloke · Guru

PnM I worked in the Industry on a short contract about 15 years ago. It was a big deal transporting them in aircraft in OZ back then. But I can't remember the details. The industry is very risk averse. A good thing IMO.