Here’s an insane question: If you were the mayor of a major city and an electric car caught fire in a local underground parking lot, how would you respond? Well, Seoul has recently found itself in that position, and the city’s responding by banning all EVs with a state of charge above 90 percent from entering parking garages. I’m sorry, what?
A Mercedes-Benz EQE electric sedan caught fire while parked in an underground garage in Seoul, damaging or destroying a reported 140 cars and evacuating residents of the building above the parking garage. This incident sparked such a national conversation that the CEO of Mercedes-Benz Korea met with residents of the affected building, and the government of Seoul has put new rules in place to try and keep everyone calm. As reported by newspaper Korea JoongAng Daily, here are those rules:
The city government earlier this month said that EVs will be advised to be charged at 90 percent or less to enter underground parking areas. As for public parking areas, an 80 percent charging limit will also be piloted at rapid chargers in the capital, with plans to extend this to private operators. Both rules are scheduled to take effect by the end of September.
This just doesn’t make sense. First of all, 100 percent on the dash doesn’t mean 100 percent as far as actual battery voltage goes. Every EV comes with battery buffers that prevent the state of charge from getting dangerously low or high, so 100 percent is still well within the safe operating range of the equipment.
Secondly, 90 percent state of charge isn’t a universal standard, because many different types of EVs use different cells and cell arrays, ergo you’re looking at different stored chemical energy across the board. A base Hyundai Kona Electric’s 48.6 kWh battery pack will have a whole lot less total energy in it at 90 percent state of charge than a GMC Hummer EV’s 212.7 kWh battery pack.
Thirdly, established protocol for the safe transport and storage of loose lithium ion batteries generally requires far lower states of charge than Seoul’s 90 percent on the dash rule. For instance, the International Air Transport Association states that lithium ion batteries transported by themselves “must be shipped at a state of charge (SoC) not exceeding 30% of their rated capacity.” So why did Seoul set the limit at 90 percent?
I’m not the only one trying to reason with this legislation, because at least one energy expert seems equally perplexed over Seoul’s new rules. Citing the aforementioned battery buffers, Professor Yoon Won-sub of a battery research centre at Sungkyunkwan University, told Korea JoongAng Daily that “Excessive charging isn’t the governing factor with a fire,” adding that ““It seems a bit like a ‘witch hunt’ blocking EV owners with cars charged 90 percent from entering underground parking lots.”
Indeed, these new policies reek of desperation to do anything to try to keep the general public happy regardless of scientific soundness. There’s no proof that an electric car charged to 90 percent has a substantially lower risk of thermal runaway than one charged to 100 percent, assuming everything’s equal and that either neither or both battery packs are defective or damaged.
You know what could help? Modern equipment both installed in structures and employed by emergency services, investing in further training on first responders, and a science-based information campaign for the general public. There are ways of saving face in the wake of such a thermal incident, but limiting EVs parked in garages to 90 percent state of charge or less ain’t it.
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In Germany, many underground garages or car park buildings don’t allow any vehicles with CNG or LPG tanks. You can see the signage at the entrance, prohibiting gasbetriebende KFZ (gas-powered motor vehicles).
Perhaps we should do the same for EV, too.
Can you just drive all the way
So how do they plan on policing this? An attendant who verifies SOC for every vehicle parking there? What if it’s at 91%? Can you just drive all the way to the end of the garage to drop your battery level enough?
A high-nickel cathode of a lithium ion battery (like most automotive NMC, NMCA, and NCA cathodes) is considerably more reactive at 100% SOC than at lower SOCs (even just 10% lower), making the likelihood of a thermal robbery event from a manufacturing defect or cell mechanical or thermal abuse less likely or harder to initiate, regardless of the overall size of the pack or individual cell within the pack. Also, the energy released is proportional to the electrical energy stored by the cell, so lower SOC will reach lower temperatures, making the risk of propagating the fire from the initial cell to others lower.
So basically, an SOC limit makes sense as a way of reducing risk until batteries improve, but LFP cells should be exempt, other in-cell innovations can help too, and I’m not sure how they’re going to monitor incoming vehicle SOC for actual implementation
If they want to be scientific about it, lithium-ion batteries must be shipped with 30% SoC or less.
If they’re gonna piss off all the EV owners out there, might as well get some actual benefit out of the law, right?
EV’s and parking structures just don’t mix. Not being a grumpy old man but its just asking for trouble.
Maybe this is just me not being up to snuff on EV’s, but if a battery at 90% charge caught fire, would that fire last longer than a battery that was only charged to 30%?
Or does it come down to the actual size and material of those batteries versus the amount of charge?
The state of charge absolutely does matter. It changes the internal chemical composition inside the battery.
A charged battery has an internal chemistry that is reactive, whereas when discharged it’s mostly inert.
A not very good analogy would be water electrolysis. Passing a d/c current through it through a cathode and anode (i.e charging it) breaks it down into hydrogen and oxygen.
Learn something new every day, thanks!
I wasn’t sure if it was just the material that dictated the strength of the fire compared to the amount of energy it was holding.
But now that I type that, it seems rather obvious.
Classic “What can we do to look like we did something without actually doing something?” move
Absolutely. I was about to post something very similar before I saw your post.
If you look further down, many others had the same thought.
I mean, this probably shows how misunderstood I am about EV’s (and the true nature of why this law now exists), but I thought it’d be a way to force owners to not constantly recharge their vehicles to 100%, because the recommended SOC I keep hearing is between 30-80% for the best battery life, and if battery degradation is high as the vehicle ages, wouldn’t the chances of thermal runaway increase by a good amount?
Damn, if I were mayor, I’d have stopped at just appointing a city Electric Vehicle Safety Commission to bring visibility to the issue, and applied to the national government for a grant to pay for it
If in an election year, maybe also call a press conference to announce a huge lawsuit against Mercedes that may or may not go anywhere
This does seem like half-assed policymaking to respond to public outcry. But something has to be done to curb the public perception of EVs as fire hazards, because every time an incident happens, the anti-EV crowd grows larger and larger.
A couple of weeks ago a whole parking lot burned down at the main international airport in my country. Fire started in a parked Telsa, and apparently insurance will not cover anything because there’s some licensing issues with the parking lot. Ultimately everyone’s gonna get fucked over either by the insurance company or the parking lot administration, but what resonates with people is that an EV started the fire, and all other parked EVs catching fire caused firefighters to contain the fire from outside the parking lot rather than going in to extinguish it – somehow fire departments are still not equipped to properly extinguish EV fires.
The transition to EVs has been pushed by policy; I sure as hell hope policy re: EVs isn’t limited to BUY MOAR going forward.
To be fair, Korea has Hyundai, and the first Bolts were partially created there with LG Chem, who have allll had battery recalls, and the recommendations were don’t charge to 100, don’t let charge go less than 10, but it’s been a few years so not sure why all the sudden, unless they’re just trying to be pro-active when all cars are EVs?
I actually leave my Bolt in ‘hilltop’ charge mode so it never does more than 90% at home, and have only ever used level 2 charging for it so hopefully I never get the thermal runs.
The first course of action is do something without any cost to the city or the citizens.
Politicians gonna politician.
The mayor of Seoul my have read my guide to electrical safety which starts with some important advice, “Volts are tricky little buggers, leave a socket switched on overnight and, come the morning you find yourself knee deep in the things”
Obviously a case of politicians deciding they needed to do “something” without resorting to any facts. However, I will point out that your proposition (“Modern equipment both installed in structures and employed by emergency services, investing in further training on first responders, and a science-based information campaign for the general public.”) is not inexpensive and requires procuring a lot of equipment and training. Is that what needs to be done long-term? Yes. Will any of that mollify the public as much as some BS “we did something”? No, not at all.
Architect here, I will expand on that. There is currently no idea of what you could do to “modify the structure”. The few EV fires testing NFPA has done hasn’t revealed a need for more sprinklers or different design in a space. Sprinklers don’t extinguish fires. They contain fires. The fire and heat is more intense, but the jury is still out on if that will increase structural damage risk. And of course the building was evacuated. That is what you do in a fire.
Should we implement firewalls in a garage? Maybe? All that does is limit spread. Given that the fire lost 100+ cars, it wasn’t the EV fire that caused that, but the cascading fire from one ICE/EV to the next. The fire fighters likely need a way to easily remove vehicles from the garage, create fire breaks between parked cars.
Fighting EV fires in an enclosed space is something that needs to be investigated further. But we don’t have good ideas out there yet.
Obviously (eye roll), they just need to ban EQE models from the parking structure.
Actually, just ban them everywhere. They’re hideous.
So a fully gassed up ICE is still coo? The benefits keep piling up to just use an ICE.
PART of the instructions we were given with our Bolts prior to the 2022 battery recall service was to manually limit them to 90% or put them in “Hilltop Mode” which if I recall correctly capped at 85%. Maybe this dude heard just that part of the news from a couple of years ago and stopped listening; it’s not unheard of for politicians to make broad policy decisions based on a partially-comprehended shadow of a memory (or one fed to them by a Wormtongue with their own agenda).