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Comment by ClumsyPilot | Hacker News Reader

Lithium battery fire cannot be 'put out'- in a normal sense. A fuel tank of petrol needs oxygen to burn, and when you spray foam on it your cut off the oxygen and the fire stops.

A battery already contains energy, all the chemicals required for the reaction are already present, and once the energy release starts, sealing it from the environment does not stop the process.

Ebike and drone batteries are large enough to be properly dangerous and fire departments make noises about them but offer no solutions. A fire extinguisher large enough for a 500wh battery weighs 12 kilos - most people can barely lift that!

We have no traceability in the battery supply chain and there is no 'battery safety box' that I could readilly buy. It is not clear if an average metal furniture would contain it. And the regulator is sleeping on the job.

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> A fire extinguisher large enough for a 500wh battery weighs 12 kilos - most people can barely lift that!

Almost everyone can lift that overhead. 90% of men and more than 50% of women can lift a bit more than twice that overhead. It's a common job requirement.

There would have to be something really wrong for an adult to struggle lifting 12kg. That's a large watermelon, and unlike the melon, the fire extinguisher got a handle.

Handheld fire extinguishers top out at that weight - because the vast majority of people will be able to use them and it's better to have two than make them any bigger.

Where on earth do you get 12 kg watermelons? Genuine curious, the ones imported here in Denmark I would guess are big if they're around 3 kg.

Warmer countries. E.g. in Italy the common water melons are at least half a meter long.

The same in Portugal. Ours can be very big.

I guess we can conclude a watermelon is a really bad weight reference unit!

  $ units 
  You have: 1 watermelon
  You want: grapes
        * 907.19
        / 0.0011023

Is there anything "units" can't convert?

  $ units 
  You have: 1 VIM user
  You want: Emacs users
        St4ck 0verflow...

Sitting even further north than Denmark, the OP did say that their melons are imported. Although it's possible to grow them in Denmark (especially in a greenhouse) perhaps it's not commercially viable.

Regardless, I guess the OP just needs to find a better grocer, local "fruit mongers" up here in frigid Sweden certainly routinely handle watermelons that are way bigger than 3 kg. :)

I get them from my garden but I weigh them in pounds. Larger ones can grow in excess of 40 lbs (close to 20 kg).

Am from the Southeastern United States.

> ...I would guess are big if they're around 3 kg

Before making a guess, try to weight them. I have hard time imagining watermelon (watermelon is the green thing unlike yellow melon) with only 3kg :) Your full water kettle already weights 2+kg.

In Istanbul the watermelons we get from the grocery store are about 4kg, the ones we buy from the road-side watermelon trucks in the summer can be 10-15kg (if their scales aren't rigged).

First source I found claims 9-11kg[1]

1: https://www.whataboutwatermelon.com/index.php/2018/08/how-he...

Most job applications for positions with any sort of physical aspect (grocery, hardware stores, maintenance) ask whether the applicant can lift 50 lbs (23 kg) over their head.

Including (I heard) semiconductor engineers. Imagine carrying dozens of kg while wearing PPE.

Not where I come from (UK) and not where I live (Norway). Can anyone else comment on how widespread this sort of requirement actually is?

Every job I've applied for that required any level of physical work had "must be able to lift 50 lbs" as a requirement. It's a little heavier than a step ladder, bags of potatoes, flour, cement and gravel are typically in that range as well. It's not an unreasonable requirement. You typically won't lift them overhead, but floor-to-shoulder is a very common lift.

> there is no 'battery safety box' that I could readilly buy

Take a look at Bat-Safe LiPo boxes. They are designed to contain the heat and prevent your entire house from going up from a drone battery fire.

okay, their largest box is actually big enough to deal with am ebike battery, this could work!

Bought one of these a while ago, super happy with the peace of mind these things provide. (I am using it mostly for drone batteries). I hope I'll never have to find out how well it actually works first hand though.

I think the standard procedure in EV car fires is to just dump water on it to conduct the heat away as fast as possible, and to keep dumping water on it until the batteries can no longer self-ignite -- which can take awhile.

Possibly amateurish take: dumping water on an alkali metal seems like not a great idea (unless you want _more_ fire, in which case by all means go for it)

The good news is, water is cold (generally), doesn't combust (generally), and there is a LOT of it.

So spraying water, while it can make it spicier for a bit, allows you to suck away enough heat fast enough that it works okayish. It's the scalable, but not ideal, solution generally.

Current guidance is don't bother with anything else, just spray it until the flames stop.

I've wondered if maybe it's possible to pack batteries with a relatively harmless material that undergoes a very energy-intensive phase change. Water's the obvious choice, but it tends to drain away rather than stick around long enough to turn to steam. Maybe there's a better material, or ways to design battery cooling systems so that a burning battery turns into a very efficient steam generator, and thus can be cooled adequately with much less water.

I've also wondered if maybe EV's should be designed with an easy-to-access coolant loop. For instance, maybe you have a fixture you can connect a garden hose to in order to pump cold water through channels in the battery modules for emergency cooling. (Most EVs have liquid cooling already, so this could be in addition to that, or maybe you hook into the existing system and the already-present coolant gets flushed out.)

>Water's the obvious choice, but it tends to drain away rather than stick around long enough to turn to steam.

just add something gel-forming into the water or some fiber/dust (even just gluten flour) that absorbs a lot of water and turns into kind of watery dough.

My Tesla caught fire but at least I now have a year's supply of sourdough bread

Problem with that is, it might block the addition of more water. If the 'way in' for the water gets blocked, but the battery continues to burn.

They do this at airports. The easy answer is foam.

The problem it turns out is making large quantities of water based foam (without making it flammable somehow) is easiest when using perflourinated compounds.

Oops.

In buildings they call your hose idea a “standpipe”

The phase transition of water from liquid to gas requires an enormous amount of energy. It’s a very good substance for cooling very hot things.

It is, but I've wondered about whether there are even better materials?

Let's say you have a battery immersed in a tank of water (aside from the contacts), and you wanted to match the amount of water to the stored energy of the cell, such that, in the event that the stored energy is accidentally released, the last of the water boils away when the battery is empty.

Apparently it takes about 2.37 kwh to boil a gallon of water. That's a lot of energy, but if you have a car with an 80kwh battery pack, you'd need about 33 gallons of water, which is probably too heavy to be a realistic option.

(Granted this is oversimplistic because the energy that comes from a burning battery might be more than the electrical energy you could get out of it just by discharging it the normal way.)

I found a wikipedia article that lists joules per gram required to vaporize various substances:

https://en.wikipedia.org/wiki/Enthalpy_of_vaporization

Water is way up there. Iron and aluminum are even higher, but it's hard to imagine even an EV fire being enough to vaporize large amounts of those. I don't think I'd want to be breathing that either, though given the "battery fire" scenario I guess that's already a given.

only if you have enough water.

if you don’t have enough water, it will just spread the fire

Luckily, one of the first criteria for if a place is habitable or not is ‘easy access to large quantities of water’, and building code wise, access to large enough quantities to put out fully formed full structure fires is required too.

It’s also relatively simple training and equipment wise (‘spray it with water until the bad flames stop’), and most locations have teams of people on call and ready to do it.

Not perfect, but it’s the best we’ve been able to come up with outside of specialized industrial environments. shrug

I wonder if they could add a "water flooding port" to the battery packs, to allow firefighters to hook up a water hose and flood that battery compartment directly. Seems like it'd be much more targeted/effective/efficient than trying to spray the exterior.

Teslas (and maybe others, I don't know) already have liquid cooling passages and piping leading to the batter pack. I do not know how feasible it would be to add a tap to that system.

The challenge of course is that there is a very small window of time where you might suspect the pack will catch on fire and it’s feasible to be close enough to a battery pack to be able to plug something into it, without being horribly burned because it’s on fire.

That length of time may be zero if the reason it is on fire is due to traumatic damage to the battery pack from a crash or similar.

It’s easier and less error prone to spray it from a distance. If it isn’t on fire yet, maybe it keeps it cool enough it never starts. If it is on fire, just keep spraying until the bad flames stop.

Lion (as me and others have come to call them, due to their "ferocious" nature) batteries contain no metallic lithium.

It's important to actually know the battery chemistry here. Lithium batteries contain metal lithium and as you say dumping water on them is not a good idea. Lithium-ion and lithium polymer on the other hand only contain lithium polymers that don't combust with water.

Lithium-Ion Battery Fires in Electric Vehicles - Safety Risks to Emergency Responders

https://youtu.be/J6eS6JzBn0k

Or just submerge the whole car:

https://www.firehouse.com/operations-training/news/21236083/...

Some people started setting cars on fire in a number of neighborhoods randomly in my city the last few weeks during the night. One of these fires happened next to my bedroom. First car was traditional ICE but the second car was hybrid and water was useless on it. The firefighters came up with a second truck and stopped the battery fire using a special foam.

Interesting note, the fire was propagating from the back to the floor - where I imagine most of the batteries lies - to the front engine bay but never burned in the cockpit area. I guess those battery equipped cars have some additionnal isolation to protect the passengers.

What model hybrid was that? Sounds like a great safety feature.

I know here in Germany some fire departments have recently bought "dunk tanks" for EV car fires. Essentially large swimming pools that they just throw the whole car in once it's on fire

The main reaction in a 'lithium battery fire' is the solvent for the electrolyte vaporizing and burning.

So actually a battery can be put out by removing oxygen.

After the electrolyte has vaporised, the problem is the anode and cathode being permanently shorted, which will keep generating heat and igniting other things. I guess you can prevent the initial fire from breaking out, but if the fire has already started, it's too late.

I'm not an expert, so I could be wrong.

>Ebike and drone batteries are large enough to be properly dangerous and fire departments make noises about them but offer no solutions.

A suitable fireproof containment bag + fire-resistant gloves is about $1200 AUD (Brimstone Preventer [1], but I'm sure alternatives are available. This one is small phone/tablet sized and rated for 10k mAh). But most people won't purchase a < $100 fire extinguisher, let alone a battery fire containment device.

>A fire extinguisher large enough for a 500wh battery weighs 12 kilos - most people can barely lift that!

SafeWork Australia (our national OSHA body) recommend loads be kept below about ~16 to 20kg for a single person without mechanical assistance[2] (or up to 55kg with), and most packaging for heavy boxes recommends two person lift starting around 25 to 36kg. 12kg should be trivial for most adults.

[1] https://www.powdersafe.com.au/fire-containment-bag-small-tab...

[2] https://www.safeworkaustralia.gov.au/system/files/documents/...

Yes, proper ones are super-expensive. I’ve seen people also use ammo cases with vents cut out, but those won’t stop gases and might actually inadvertently function as a flame thrower.

The standard weight (derived by US NIOSH studies) that can be lifted in workplaces is 30 kg, hence most heavy packages are 25 kg (think of a bag of cement/plaster/etc.) in most EU, see:

https://news.ycombinator.com/item?id=31465982

> This Bag Has Contained 10,000 mAh Thermal Runaway Events.

Is it just me, or is their choice to use mAh—a meaningless unit in this context—a major red flag? Five figures for a bag, and they can’t even get their units right? Is there some “standard voltage” of which I’m not aware?

> Our bags were tested on 4 separate occasions with an overheated laptop, each containing a 3,500mAh - 4500mAh Lithium-Ion battery. The computers melted and burned during these 1 hour tests. The bags showed zero exterior damage. The pull over flaps combined with our carbon liner also absorbed a significant amount of smoke.

That’s meaningless unless we know the voltage. Amp-hours don’t measure energy.

> Tests were conducted with an overheated laptop and cell phone battery (combined capacity of 8,000 mAh- twice as much power as a typical laptop). Our bag passed this test with 100% containment.

Amp-hours don’t measure power—that’d be watts. Neither are measures of energy. This is misleading at best.

Maybe I’m being pedantic, but if I’m paying five figures for a bag and trusting my life with this company, I think it’s fair to expect technical correctness in the product description. This reads like a scam—maybe it isn’t, but the wording is far from reassuring.

> Is it just me, or is their choice to use mAh—a meaningless unit in this context—a major red flag? Five figures for a bag, and they can’t even get their units right? Is there some “standard voltage” of which I’m not aware?

Most lithium-based rechargeable cells are nominally between 3.2 and 3.8 volts and are rated in mAh[1]. I would much prefer that they were rated in watt-hours, but they are not.

1: I've seen LMOs with nominal voltages as high as 3.8; LiFePO4 are Nominally 3.2; I think there are some exotic electrode chemistries that are nominally under 3V, but 3.2-3.8 is a fairly solid range for the nominal voltage; voltages at full charge and "empty" will be higher and lower respectively.

> But most people won't purchase a < $100 fire extinguisher, let alone a battery fire containment device.

$1,100 to contain fire from a phone? No-one is buying it because that's is a terrible deal!

An E-bike battery is like 20x larger, is a containment for e-bike going to cost as much as a car?

But yeah let's blame the consumer, the industry can't be at fault!

Also I had a fire extinguisher, they have an expiration date and now I don't have one.

> 12 kilos - most people can barely lift that!

Not that I'm disagreeing with your overall point, but this I find particularly surprising? My electric scooter weighs 14 kilograms and I carry it everywhere.

That said, adding an extra 12 kilos to my backpack would be annoying, for sure.

Huh. I add 15kg of weight plates to my backpack, for fun. And I walk to work.

Huh, I put 30kg of lead on each leg for fun when hiking, when jogging to work, anytime, really. Plus that heavy backpack, of course!

I considered doing that, but it was more easier to just gain 15kg of weight to my actual body.

I often wonder about this while hiking or riding my dirt bike out on the trails. Gas powered dirt bikes are prohibited almost everywhere due to risk of fire and chemical contamination.

However, more and more I am seeing e-bikes ripping around on hiking trails that would get me and my dirt bikes a hefty fine and impound. The risk of fire and contamination is practically the same. And these e-bikes are typically driven by the same people who would call the cops on a gas powered bike on the same trail. The irony is they ride and do peaceful yoga on trails that were made by motor vehicles whose owners were probably gentrified out of their homes. Go figure.

I’m surprised e-bikes are allowed, they’re also prohibited on the trails here and considered OHV.

Regarding fire I’d be worried about the hot exhaust on a dry 100+ day.

Most trail bikes come from the factory with spark arrestors with the major exception being cheap Chinese branded bikes.

And I don't think the temperature of the exhaust stream would be enough to light a match 6" away from the tip of the muffler. You'd have to reef on the bike and park it in a pile of dry leaves up to the exhaust header for temperature alone to start a fire.

The problem is when you dump the bike. If you dump it on a tree or a rock you can fracture the gas tank (releasing fuel) or the crankcase (releasing oil). Or if you tip the bike completely over the fuel will eventually be released. Releasing these doesn't imply fire is inevitable. You still need ignition. If a fire starts you can try to smother it.

On an electric bike the same situation applies. If you dump the bike and fracture the battery (that is often attached to the downtube of the frame) then you will have a catastrophic chemical reaction. Thermal runaway is almost guaranteed. You can't even put it out by smothering it.

Furthermore, most lithium battery controllers in consumer devices are proprietary and most consumers have no idea what their true capabilities and thresholds are. Some batteries might be inherently safer than others due to simple firmware that they don't know exists and have no visibility into. There's really no hiding the capabilities of an analog machine.

> Most trail bikes come from the factory with spark arrestors

And most riders immediately remove them because they gunk up with soot and restrict the exhaust.

It's my understanding that e-bikes which can ride on traditional "bike" trails (I'm used to this rule for bike lanes) are limited to a relatively human-accessible speed, usually 15 or 20 mph in the US. Are these e-bike riders going faster than that? If so, they might be breaking the law.

I had assumed dirt bikes were banned on these trails due to weight and speed, leading to damage to the trail, risks to other trail users and potential structural failure of the often wooden bridges. The risk of fire with a modern gasoline engine is quite small, though air quality effects are significant.

There are many people bypassing the limit using hacks or on some cheap chinese kits just by going in the settings (usually a button combo, knowledge widely available on the internet).

Yes it is illegal but in the same way the 50cc mopeds are supposed to be limited at 45kph (27mph) and all the kids always modified them to go faster. I believe there has always been more unrestricted 50cc mopeds than legal ones in the street. Only some old people kept them restricted.

Most people are willing to take the risk of not getting insurance coverage and a fine once in a while to gain a few minutes per day and be the king of the road. Most only have third party insurance anyway and a bicycle or a moped don't usually create that much physical damage to other vehicules. It only becomes ugly when people hit pedestrians but thankfully and for obvious reasons it is a much rarer event than car drivers doing it.

50cc moped is over 2000W, thats almost 10 times the power of a typical ebike at 250W

> The risk of fire and contamination is practically the same.

Source? There's very little risk of an e-bike catching fire unless you're charging the battery. Most of the risk will be at home.

Battery fires gets a lot of attention because they're a new thing, but they're far safer than ICE alternatives in almost all circumstances. At least that's what the fire department here in Norway says, and they have pretty good experience with EVs by now.

You obviously don't trail ride.

When you ride trails you sometimes fall down. Sometimes you catch a branch with your bars. Sometimes your bike lands on rocks or logs.

The down tube of an ebike frame is often where the batteries are located. This area takes a lot of abuse from the front wheel and is in perfect position to take damage during frontal impact.

Look up my YT @Platinum_Racing to see an example of terrain that could very easily destroy an ebike or gas bike.

> Gas powered dirt bikes are prohibited almost everywhere due to risk of fire and chemical contamination.

All gas powered bikes generate heat and pollution. (dry grass + hot pipes for example)

Only defective ebikes will generate heat and pollution

Firefighters struggle lifting 24.5 lbs?

Firefighters aren't 'most people'.

I'd guess that most people can lift 12kg. But lifting and wielding ain't the same.

12kg is like a two year old child or a small-to-medium sized dog.

Yes.

12kg shouldn't be much of a problem for most people, if the weight comes in the shape of a dumbbell and stuff ain't on fire.

But wielding a toddler-sized implement awkwardly in front of a fire while you are a bit panicking yourself, might be a struggle for many people.

Especially since you probably never practiced this, and you might even have to hold the thing one-handed, so you can aim with the other hand

When you get to 12kg it usually mean a cylinder and a hose. You have the cylinder with handle in one hand and the hose in other.

Fire extinguishers are easier to carry than a dumbbell. They're a tall cylinder with a handle at the top.

Also it only takes 10-30 seconds to discharge a 30lb fire extinguisher[1] with no pause. This is not a marathon.

[1] scroll down to table in https://blog.qrfs.com/66-ultimate-guide-to-fire-extinguisher...

I mean average housewife and grandpa.

Also you are not benchpressing in optimal position, you need to hold it at an awkward angle.

In doubt, take two metal buckets, fill both of them half with sand, and when a lithium device starts smoking put it in one bucket and smother it with sand, or at least place the charger in the bucket. Friend of mine does that with e-cigarette batteries.

I think the commercial aircraft solution is to just put them in jugs of water.

12kg is 26 pounds. Most people can hold a bowling ball, which weights about half that, in one hand without too much difficulty.

A 5 gallon (18.9 L) jug of water weighs... well, almost 19 kilos, and most people have no problem lifting one.

So what happens after the next big earthquake in a place like SF?

Why would an earthquake directly cause batteries to set on fire? They are already subjected to significantly more vibration and movement in EVs

Crushing.

Big earthquake implies things like UMBs collapsing.

What are UMBs?

Upper Memory Blocks, the area between the 640 KiB and 1 MiB range that becomes available on 286+ machines in real mode once the A20 address line is no longer held low by the keyboard controller.

Thanks, I should add MEMMAKER.EXE to my earthquake kit.

No idea, but from context, maybe they meant https://en.wikipedia.org/wiki/Multiple_Dwelling_Unit? Really weird phrasing either way.

Ureinforced Masonry Building, any firefight in SF will tell you the city is full of them.

https://en.m.wikipedia.org/wiki/Unreinforced_masonry_buildin...

Ureinforced Masonry Building, any firefight in SF will tell you the city is full of them.

https://en.m.wikipedia.org/wiki/Unreinforced_masonry_buildin...

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