[Jayne]

I'm looking for opinions on carrying a fire extinguisher in an EV.

I actually looked at the old one that was in my boot today and discovered it was made in 2004 and warranty expired 2009. So it really should be replaced. Or should it?

Most fire extinguishers are tiny. I can't imagine they'd put out much. And my first instinct is if there's a fire in the car get out and move as far away as possible while phoning 999. But I do go to very rural areas where it could easily take 30+ min for help to arrive. And it would be a shame for the whole car to go up in flames if I could prevent it.

So opinions on what, if any, fire extinguisher should I get please. And what size?

 

[cah197]

Probably CO2 or HFFF. But I doubt you’d ever get one big enough to put out a battery fire, more to stop a small fire getting out of hand.

However I’ve come across about three ICEs on fire in the past 6 months, so I was rather thinking to get one so I could help with one of these fires, next time I came across one.

Thanks for the reminder.

 

[Jayne]

Yeah, a battery fire will do whatever it wants to do. I don't think anything consumer grade will stop it. I am just about to look up where my car's HV battery emergency disconnection switch is though. That might help.

Fire extinguisher would just be for any small fires to reduce the chance of things getting out of hand. Good point about helping other vehicles though.

 

[cah197]

Just looked on Amazon and they’re all powder, which are very messy. I suppose they’d do the job though.

Is there an HV disconnect? I thought is was automatic on the contractors? Or by the fire brigade cutting a cable.

 

[Jayne]

they’re all powder, which are very messy.

I think I'll just go with powder and accept the mess. We'll, actually, I hope I'll never need it. But mess can be cleaned. A burnt out car needs replaced.

Is there an HV disconnect? I thought is was automatic on the contractors? Or by the fire brigade cutting a cable.

I'd seen it mentioned about Teslas and Leafs. A quick Google found this. It's from an American site, but other than the steering wheel being on the wrong side I expect its similar. I've not been out to have a look in the car yet.

 

[Bol d'or]

I can vouch for the fact powder ones are messy, I once had one go off in the boot of my (then) Renault 19.
Ironically, it was such a mess after that that setting it on fire seemed a good answer.

 

[RunningStrong]

Get a water mist (dry water) extinguisher with de-ionised water. Good upto 1000V electrical fires.

 

[cah197]

The other thing to bear in mind is powder will do little to cool the fire, which is usually what keeps battery fires going. Thermal runaway.

Powder is good for fuel fires.

 

[RunningStrong]

The other thing to bear in mind is powder will do little to cool the fire, which is usually what keeps battery fires going. Thermal runaway.

Powder is good for fuel fires.

No fire extinguisher is going to be sufficient to stop a battery pack on thermal runaway.

 

[cah197]

No fire extinguisher is going to be sufficient to stop a battery pack on thermal runaway.

Yes, we mentioned this at the start of the thread.

Do keep up.

 

[RunningStrong]

Yes, we mentioned this at the start of the thread.

Do keep up.

So why mention powder specifically when the same can be said of all extinguishers, old chum?

 

[richtrash]

Lidl had fire extinguishers recently I think they were 1 kg powder fire extinguishers for £7.99, checked and they weren't cheap Chinese they were cheap Italian.

 

[Grumpy-b]

Other than a simple 12v related fire , there is no point in getting involved with a main pack fire.
Water is the only solution and a great deal of it.
If you are thinking of an extinguisher for a car, many people dont really get the pointlessness of fire extinguishers being suitable for Electrical fires, because they are aimed at AC mains fires. Not DC stand alone fires.
If you use water on a mains fire you will get hurt, if you use water on a DC fire in a battery pack, its just giving a pathway through the battery circuits not through you, so unless you are connected to one of the battery poles you will be OK. But water is what is needed to reduce the temperature and remove the sustainers of the self maintaining fire .
On a pack fire the cells are a bit like setting of a flare, they will self generate all they need to cause combustion, until they either burn out or are cooled below the temp at which the gasses will be generated.
If your EV somehow catches fire, move it to open ground, call the fire brigade and keep away from the smoke. Dont faff around trying to squirt any form of extinguisher at the car, you will make no difference at all, but could get a lung full of fairly unfriendly smoke and gas.
Just squirting an extinguisher at the burning exterior plastics, might look good but wont do anything of real value.
Spend you time getting other cars moved and keeping people away.

 

[dialcottage]

Just as a bit of boring chemistry, the powder used in extinguishers is sodium hydrogen carbonate - the same chemical often used in baking, and sometimes called bicarbonate of soda.

When heated above about 80 degrees C, sodium hydrogen carbonate thermally decomposes. The decomposition reaction absorbs considerable energy, thus cooling the fire. The products of the decomposition are sodium carbonate (aka washing soda, so alkaline, but washawayable), carbon dioxide and water vapour (steam). The carbon dioxide in particular acts as a blanket to prevent oxygen reaching the fire.

Dry powder extinguishers are pretty effective, but the best thing for a fire is really half a dozen fireman and a big red fire engine.

: o )

 

[Grumpy-b]

Believe me powder will do nothing effective on a pack fire and you cant of course get anywhere near the pack anyway. Its in a casing hidden away, the best you will do is to cover the metal casing and that will do nothing of value.
As an example, I had some 160ah Lifepo4 Cells (Dont burn, get hot and melty) that were still pouring out smoke after 5 mins of total immersion with the hose still running.
Really believe me there is no point of messing around with a pack fire, you cant get to the cells, and neither can a fire hose, the best you can do is to douse the fire and keep the heat down so you dont completely destroy the road surface.
It would be really good if all packs had an emergency watering hole, but then there would be the issue of errant chemicals, but thats ignoring whats going to get washed out with a full blown fire.
EV fires are not an issue that makers seem to take on board, so not really making for solutions to be incorporated. There are not any standards being applied by all makers, to for example install and have a common dousing point/ connection.
I got involved with one UK car company to comment on a Lifepo4, meltdown they had. This discussion also involved the local fire brigade who attended the initial event. They actually made things worse by cutting cables, not realising the cables led to a separate part of the pack, so were in effect still live and 30v at potentially 400+ amps will do a lot of damage. But they did douse the main source of heat, so good work.

 

[Jayne]

Excellent lessons up there folks, I hadn't realised powder fire extinguishers are basically baking soda.

Looking back I realise I didn't make it clear in my original post that I know a battery fire will do whatever it wants and nothing I do, bar getting the fire brigade, will do anything to stop it. And even then it's not a given it'll go out and stay out.

But is the consensus for other small fires either cheap and messy powder or expensive, much less messy water mist?

 

[dialcottage]

But is the consensus for other small fires either cheap and messy powder or expensive, much less messy water mist?

In an earlier life I was sent on a fire brigade organised course where I had the opportunity to use a range of different extinguishers to attempt to put out a range of small fires. It was, I must confess, a great day out!

My choice is definitely for a dry powder extinguisher. The mess caused by dry powder is minimal compared to any fire damage, and shouldn't come into your calculations. Excess powder can be vacuumed or washed away with water. Dry powder can be used on just about any fire - except a chip-pan type fire which would result in burning oil being spread around - without making decisions about whether it's safe to use, and anyone can use it.

Really, though, the message I got from the fire brigade on my day out was to call 999 as soon as you realise you have a problem, and that fire extinguishers are very limited in what they can do.

 

[donald]

Fire extinguishers in cars are mandatory in some countries. This is for the same reason as carrying a first aid kit; that reason is not for you but to help others.

If your car is on fire, run away and call fire services. If you can't get out of the car then no point having one in the boot. So only reason for everyone else to carry one is to help you get out when you can't by yourself.

 

[RunningStrong]

But is the consensus for other small fires either cheap and messy powder or expensive, much less messy water mist?

Water mist is still quite new, but it is widely replacing powder.

 

[zap fizzle]

People who steal from cars have been known to empty any extinguishers found into or over the car or surrounds.

Powder is VERY messy.

I wouldn't carry a powder one for this reason alone. I've seen the aftermath and the broken window was nothing in comparison.