236 - The EV Fire Episode

Gary C:

Hi, I'm Gary and this is EV Musings, a podcast about renewables, electric vehicles and things that are interesting to electric vehicle owners. And on the show today, we'll be looking at electric vehicle fires. Before we start, I wanted to remind you of the roundtable episode at the end of the season.

Lots of great guests and great interviews. So keep an ear out for that one. Now our main topic of discussion today is EV fires.

So in July of last year, there was a large transporter ship, the Fremantle Highway, in the North Seas just off the Dutch coast. It was carrying approximately 3,000 cars, most of German ones, heading for Singapore. Amongst the 3,000 cars were 500 electric cars.

A fire broke out. It burned for a long time and one crew member was tragically killed as he tried to make his escape. Naturally, the press were all over this and the word went out immediately that it was an electric car that caused it.

And with absolutely no evidence whatsoever, this spread like, if we'll excuse the pun, wildfire until everyone was convinced that the fire was caused by an electric vehicle. The logic seemed to be, despite the fact the number of vehicles carrying explosive and flammable liquids on board outnumbers those without by a factor of 5, it must be the lithium ion batteries that caused the fire. The uproar on social media was fierce, with fossil fuel supporters saying that EVs were a hazard and shouldn't be allowed on the road, etc, etc.

Except it wasn't true. When they finally got the ship to port and investigated the cargo, they found that all the cars that were alight were on the higher decks, they were all fossil fuel cars, and the 500 electric cars were untouched on lower decks. But by then the damage was done.

It was magnified when, a short while later, a massive fire broke out at Luton Airport in one of the car parks there. Hundreds of cars burned and, without a shred of evidence, the rumour went round that it was an EV that caused it. Once again, the subsequent investigation showed that it was actually a fossil fuel vehicle that caused it.

Now, before we go any further, I need you to put your mind to rest. For many years, people have been driving around in vehicles that need highly explosive fuel to work. They operate using an internal combustion engine, and they have a tank of explosive fuel sitting somewhere in the vehicle, usually underneath or slightly behind the rear passenger seat.

For some reason, this has not seemed to be an issue with anybody, despite the ridiculously huge number of vehicle fires that happen worldwide. This is particularly apparent when you put dodgy electric wiring in the mix, where sparks can happen without warning. But as soon as we moved across to an electric powertrain, the whole world suddenly became concerned that the batteries powering EVs would be a huge fire risk and that the safety of the population was in danger.

Now it is, of course, absolute rubbish. But as we've just said, it didn't stop citizen journalists jumping on social media and decrying the fact that the Luton Airport fire was started by an EV. It wasn't.

It was a diesel Land Rover, not even a hybrid. And that the Fremantle Highway of Holland was also an EV fire. It wasn't.

In fact, we're at the stage now where any vehicle fire that makes its way onto social media will habitually be labelled as an electric vehicle fire, regardless of the truth. You may have heard recently that a fire engine burst into flames in Germany as a result of a battery fire burning down the fire station in which it was located. The implication was that this was a battery electric vehicle where the traction battery had ignited.

In fact, it was a diesel vehicle, and there was a power tool nearby with a lithium battery and that ignited and burnt down the fire station. The statistics show that you're almost, well, anything between 11 and 60 times more likely to experience a vehicle fire in an internal combustion engine than you are in an electric car, depending on where in the world you live. Recent figures released by the AA indicate that the actual number of car fires in the UK is dropping, and they attribute this to the fact that there are more and more plug-in vehicles on the road, which means less and less opportunity for internal combustion engine fires to occur.

om the UK indicate that since: 2010

Now it's worth at this point stopping for a moment and mentioning that there will be fires in electric cars where the cause is nothing to do with the battery. It could be wiring-related for something else in the vehicle, it could be due to something flammable inside the vehicle igniting, it could be any number of reasons which are not related to batteries. Now records show that there have been a few fires in electric cars that are along this sort of vein, but very, very few of them caused the battery to ignite.

A recent post by Australian EV safety organisation EV FireSafe indicated that they've been able to identify and report on 511 incidents of thermal runaway, which is a fire in the traction battery of a battery electric vehicle or a plug-in hybrid electric vehicle. 511 incidents globally in 14 years, which comes out at 0. 7 fires per week.

So that's 0. 7 fires per week globally for electric vehicles compared with 400 per week just in the UK for fossil fuel cars. Now there are currently approximately 40 million electric vehicles on the road if we include plug-in hybrids.

The four leading causes of battery fires have not changed in the last 12 months. 119 have been caused by collisions, 28 have been caused by the vehicle being submerged in water, 45 have been due to a battery fault in manufacturing and 22 were an external fire that spread to the EV. The vast majority of these fires were the jet-like flame type where the battery heats up and spits flame out from under the car.

EV battery fires since: 2021

Of the 8 fires noted in the report, only one of them was from an EV that was plugged in and charging at the time. The report is also at pains to note that a normally operating electric car connected to a compliant electric car service provider. car charger that is installed to a relevant wiring standard by a qualified and experienced person cannot cause a battery fire.

Listen for the thunk when the charge starts. That's the systems checking for ground faults, overheating, voltage, positive connections etc. There are another three Australian EV battery fires they've been looking into.

Two took place in EV conversion workshops and one happened where a pack was left on the ground for several months i. e. not in normal operation.

Those are not included in the figures I've quoted. But it also has to be said that there have been examples of electric vehicle fires where the cause of it was the battery and those are the ones I want to talk about today because they're the nasty ones. But let's start by talking about why a battery actually burns, how it burns and what the issues are relating to putting it out.

I'm joined today by Dr Ewan McTurk.

Euan M :

king on and driving EVs since: 2009

Gary C:

So let me start by asking the key question around battery fires. What causes them and how do they spread?

Euan M:

the very least throughout the: 2010

So they contain cobalt which ironically is in there to improve stability but generally if it's a cobalt containing chemistry it tends to be more flammable. So if you were to do something really stupid like massively overcharge it and then poke it with a big stick, a big metal conductive stick, then you could get that NMC cell to undergo thermal runaway whereby even if you were to remove any external load from it, any external charge or discharge, it would continue to heat itself up because it's rapidly discharging itself through any kind of internal short. That results in a build up of flammable gases, quite a large build up of flammable gases at that.

And inevitably you've got your triangle of fire, your fuel, your heat and the thing about NMC is, as I said, is lithium nickel manganese cobalt oxide. So there's oxygen in there and the oxygen is not particularly tightly bound to it so it gives up quite a lot of that oxygen and that's the last part of your triangle of fire and you've got yourself a jet of flame. And admittedly there are potentially ways that you could control where that jet of flame goes and you can manage it a bit like managing the burning of a forest fire and you can actually control the situation quite effectively by letting itself burn out.

But there are firefighting techniques that we'll inevitably come back to in a minute that can tackle that.

Gary C:

Now batteries are a combination of different materials, some related to the anode, some related to the cathode. Are different combinations more likely to burn?

Euan M:

If you look, lithium iron phosphate, so that is lithium rust and a bit of fertiliser that's in those. They're super cheap materials, super ethical, longer lasting, etc, etc and generally regarded as being safer. So what happens if they undergo thermal runaway?

Well there's a volume of flammable gas that is produced but not as much of a volume, typically speaking, as there is with an NMC cell. But when that gas is venting there's not as much oxygen in it because oxygen is bound far more tightly to the LFP cathode positive electrode structure. So that triangle of fire isn't quite complete.

Yes, there's oxygen in the air but it's far less likely to spontaneously combust. That said, you know, that is a gas cloud or a vapour cloud of flammable gases. So if it's in an enclosed space you want to make sure that you've got a very good ventilation system to extract that in case there is a spontaneous explosion of that vapour cloud.

But generally speaking LFP is considered safer than NMC, although there is a lot of research going on into not just improving the fire safety of the fundamental electric industry so it doesn't catch fire, but also into firefighting techniques and the causes of fires and best techniques to put them out. So yeah, LFP is generally safer. I have seen some videos of LFP EVs that have managed to catch fire but it could be because there was some faulty electrical systems that started it.

And LFP, much like my wooden office desk, if I was to stand there for long enough it would go, okay then I'll join in and it would catch fire. And quite a lot of these LFP fires in comparison to the jet of flame you get from NMC do look as if, and I exaggerate a little bit here, but it does look as if you could fill up a bucket of water and chuck it over it and that would deal with it, much like a smouldering wooden office desk.

Gary C:

So now you know chapter and verse on the battery side of things.

Let's talk about what's the state of play when it comes to EV fires and extinguishing them. As Dr. Matturk already mentioned, one of the issues that arises with battery fires is that in certain chemistries they tend to produce their own accelerant with a combination of fuel, heat and oxygen.

This triangle of fire tends to be pretty difficult to extinguish without a great deal of water. The commonly accepted way of dealing with this is to drop the vehicle into a skip filled with water and let it sit there until it stops burning. But that's not always feasible or even possible.

So what else is out there? One of the more popular solutions is a tool called a lance. This is effectively a really powerful jet wash system with a hyper-localised outlet.

This outlet can be aimed directly at the battery to cool it down. But what makes this even more effective is that the fluid that's used is laced with tiny granules of sand that turn the water jet into an abrasive cutting stream. This stream penetrates the battery casing and delivers the cold water directly to the inside of the battery, hereby cooling it down and removing one of the three elements of the fire triangle, heat.

This lance solution can be fitted to a small truck with a water source on the back. On one truck about the size of a Toyota Land Cruiser can carry enough water to extinguish four battery fires. The benefit of this solution is that it can go into low-roofed car parks and extinguish fires that can't be reached by traditional fire engines.

Initial testing indicates thermal runaway can be controlled in minutes due to direct application of water to cells. However this does involve firefighters getting quite close to a burning vehicle and if the lance were to touch any live parts of the car there could be an electrocution risk. Another option is a fire blanket.

Fire blankets have been around for decades but this particular version is particularly effective. It's made of a strong fire resistant material obviously. The aim is for the fire brigade to walk either side of the burning vehicle with this blanket and drape it over the car.

It doesn't extinguish the fire but what it does is it contains the heat, the flames and the gases and this reduces the risk to nearby structures and allows the car to burn without spreading the fire. I'll link a video in the show notes that demonstrates how effective a fire blanket can be. There are downsides to this of course.

The toxic fumes do not disappear and if a blanket is in the area where wind could attack it a lifting effect could release these toxic clouds into the neighborhood of the incident which isn't good. There are however only three actual recommended solutions for battery fires. Cool, burn, submerge.

So let's go through those in a little bit more detail. Cooling a fire is a simple case of dousing the vehicle with water. Get the fire brigade in, turn the hoses on and just let the thing cool down.

Now the downside to this it uses a lot of water, nominally about 10 000 liters per car. Burn is, no prizes for guessing, is when you literally leave the vehicle to burn. Oftentimes what you can do if the vehicle is in the right location is tip it on its side, allow it to burn and you can then use thermal cameras to more easily monitor the heat.

The pros to this are that it doesn't use any water, the fire will remove all the energy in the battery and the risk of second re-ignition. However, there are risks associated with pollution from the fire, toxic fumes etc and the time taken could be quite extensive. The third option, submerge, is when the vehicle is literally lifted into a tank filled with water and left there.

This is usually a quick solution that will solve the problem, the fire, in the shortest length of time. However, it too will use a lot of water and the submerged vehicle will need to be left there for several weeks. Now I mentioned secondary ignition just then, let's talk a little bit about that shall we.

Once a traction battery fire is out the safe removal of the vehicle from the scene is the next priority and this is where the risk of secondary ignition comes in. When a battery cell has gone into thermal runaway and ignited it's usually destroyed and it cannot ignite again but other nearby cells that were not ignited but were heat impacted by the fire might go into thermal runaway later on and these bits of the battery produce what's called stranded energy. According to EV Firesafe, which is an Australian-based organisation that researches electric vehicle battery fires and emergency response by establishing the world's only detailed and verified incident database for firing EVs, they say quote, our research found 13% of the vehicles we studied reignited following initial suppression with two reports stating that the vehicle reignited multiple times over a period of several hours, in five cases the vehicle reignited while on a tow truck, additionally one vehicle had four separate re-ignition events and another reignited 68 days after the initial incident close quotes.

So stranded energy and the risk of re-ignition is still something of a risk that's why of the three solutions we mentioned already burn is the one that minimises this risk almost completely. So there you have it, EV fires do occur a tiny tiny minority of them are related to the battery itself most of them are collateral damage caused by something else such as a collision or a building fire. Worldwide the number of thermal runaway events is tiny compared with a the number of fires in internal combustion engines proportionally and b the number of EVs on the road.

If an EV does set on fire chances are the easiest solution is to either let it burn, douse it with water or submerge it for a couple of weeks. Either solution will cause the same result a written off EV. But bear all this in mind when you see some video or photo on social media or even mainstream media which purports to show an EV on fire.

There's a very good chance it's not actually an EV, there's a reasonable chance that if it is an EV it's not a battery fire but a fire caused by some other factor such as a collision or arson and there's a tiny chance it is an EV battery fire caused by the battery itself. If you do come across an EV fire make sure you stay away from it, poisonous fumes can surround it, call the fire department and clear everyone away from it. They'll come and either smother it with a blanket, dunk it in water or just let it burn and that's about the only thing you can do with it.

This season we're looking at raising the awareness of carbon literacy with our listeners and one way we're doing that is with a carbon fact as read by carbon literacy trainer Anne Snelson.

Anne S:

To save money, fuel, electricity and emissions try eco-friendly driving if you possibly can. Accelerate and brake less and make sure that if you're driving a petrol or diesel car you're using higher gears.

Check your tire pressure before you travel long distances and drive at 70 on motorways rather than sneaking over the limit.

Gary C:

It's time for a cool EV or renewable thing to share with you listeners. Two EV experts drove a Lucid Grand Touring from Los Angeles to New York covering over 2,800 miles with only seven charging stops.

They found that charging infrastructure has improved significantly in the US making long distance travel in electric vehicles more feasible. Despite some minor issues they concluded that with proper planning coast-to-coast EV trips are now very doable. Now we've seen trips like this done with Teslas as well as a record-breaking trip done by a Porsche Taycan with the shortest charging time.

This is the first to be done based on charging stops rather than charging speed and it proves that the infrastructure is getting there. By the way if you read the comments on the linked article in the show notes you'll find at least one comment along the lines of I can drive 1,300 miles in one go in my 16 year old Passat 1. 6 TDI and refuel in three minutes.

Now obviously this is without considering the fact that total distance you can drive without needing to replenish your fuel source is irrelevant and it does not correlate at all to total distance you can drive without needing to physically stop.

I hope you enjoyed listening to today’s show.

It was put together this week with the help of Dr Euan McTurk and the good folks at EV Fire Safe in Australia. Many thanks for their input. If you want me to get EV Fire Safe on to talk in more detail about EV Fires let me know and I’ll see what I can do for next Season.

If you have any thoughts, comments, criticisms or other general messages to pass on to me I can be reached at info@EVMusings.com

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Check out the links in the show notes for more information as well as a link to my regular EV Musings newsletter and associated articles.

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Thanks as always to my co founder Simone. You know he posted photos of himself on the beach last year wearing his Speedos. He marked it #sexybeast. I asked his wife if she still found him attractive and she told me it’s a different kind of appeal.

Euan M:

Much like a smoldering wooden office desk.

Gary C:

Thanks for listening Bye!