California crews use 4,500 gallons of water to put out Tesla fire | Hacker News Reader

California crews use 4,500 gallons of water to put out Tesla fire

ktvu.com

4 pointslando231917 comments

The Tesla emergency guide mentions using lots of water, or as a backup, dry chemicals, but not foam or submersion. (Why not?)

Thinking way outside the box:

- Can these fires be extinguished with sand? Large air-powered sand pumps exist for metal casting. A "battery-fire truck" could haul tons of sand, an air powered sand pump, and a metal "hose" to deliver sand onto the vehicle from a distance. (https://www.macawber.com/products/pneumatic-conveying/sandpu...)

- What about letting it burn out in a safe way, like a covered grease fire? Winch the vehicle into a fire-proof box (a shipping container lined with refractory brick.) Let it be until it burns out, or if insulated well enough, transfer it to a safer location.

Sand is a good heat insulator. It may take a very long time before the car cools down enough that it doesn't catch fire again once re-exposed to air.

I don't know why Tesla doesn't recommend submersion.

Here's a Dutch solution - a water container for storing a car for 24 hours while it cools down. https://www.techeblog.com/bmw-i8-water-container-firefighter... Looks like it also needs a crane, and is done after the fire appears to be put out.

We had some car fires here recently (arson, alas). The smoke can be toxic. We were advised to close our windows. Best there to put it out rather than let it burn even in a fire-proof box.

The fire-proof box still needs cooling.

From the Tesla First Responders guide ...

USE WATER TO FIGHT A HIGH VOLTAGE BATTERY FIRE. If the battery catches fire, is exposed to high heat, or is generating heat or gases, use large amounts of water to cool the battery. It can take between approximately 3,000-8,000 gallons (11,356-30,283 liters) of water, applied directly to the battery, to fully extinguish and cool down a battery fire; always establish or request additional water supply early. If water is not immediately available, use CO2, dry chemicals, or another typical fire-extinguishing agent to fight the fire until water is available. NOTE: Tesla does not recommend the use of foam on electric vehicles. Apply water directly to the battery. If safety permits, lift or tilt the vehicle for more direct access to the battery (see chapter 2). Water may be applied onto the pack from a safe distance ONLY if a natural opening (such as a vent or opening from a collision) already exists. Do not open the battery for the purpose of cooling it. Tesla does not recommend placing the vehicle in a large tank of water. The use of a Thermal Imagery Camera or Infrared (TIC or IR) is recommended to monitor battery temperatures during the cooling process. Continue to use water until the battery has reached ambient temperatures or below, indicated by the thermal imagery camera. When utilizing a thermal imaging camera, allow enough time, once the application of water has stopped, to allow for heat within the battery to transfer to the battery enclosure.

That's like two bags of almonds worth of water.

is that true? if so, that's scary.

Drive down CA I-5 and you'll see groves of dead almond trees and angry signs from growers bemoaning the fact they can't continue to suck the life force from the surrounding area for profit. Makes great firewood, though.

I think the intent is for this to be outrage inducing? That's actually an astonishingly small amount for an industrial fire.

Shouldn't the comparison be to an ICE car fire? An industrial fire would include factories and other large buildings.

"Normally a car fire you can put out with 500 to 1,000 gallons of water" - https://www.businessinsider.com/tesla-crash-fire-lithium-bat...

"By comparison, a typical fire involving an internal combustion car can often be quickly put out with approximately 300 gallons of water" - https://www.nbcnews.com/business/autos/federal-regulators-wa...

"Crews were able to put the flames out using about 600 gallons of water in about an hour," - https://patch.com/massachusetts/westford/car-catches-fire-we...

"Firefighters quickly extinguished the blaze with about 300 gallons of water." - https://kiwaradio.com/lightssirens/car-destroyed-in-friday-m...

"Candy said it takes about 2-to-3 hundred gallons of water to put out a fire in a car with a combustion engine, but that an electric car fire can require 10 times more water." - https://globalnews.ca/news/6484767/electric-car-fire-trainin...

Last i heard, an electric car can burn for days.

Yes, the linked-to news piece end with "It can take as long as 24 hours to put out, according to a guide for first responders for the Tesla Model S."

However, my point was that "industrial fire" isn't a useful comparison.

That sounds like a lot until you learn that the average homeowner uses about that much to water the lawn. Once.

I would really be interested in seeing a source for that. That is three times the amount of water my household uses in a month (granted I dont water my entire lawn).

Rule of thumb is 1 inch of water, which works out to 623 gallons per 1,000 square feet. In the United States, residential lawns average 10,871 square feet[1]. 10,871 / 1000 * 623 = 6772.633

1 https://www.homeadvisor.com/r/average-yard-size-by-state/

That's 1 inch of water per week.

Most people don't live in a desert, so some of that 1 inch of water comes from rain. That is, assume each watering uses 1 inch and the watering is one per week, then:

  6772 gal / week * 52 weeks = 352,000 gallons per year.

The average American family uses about 300 gallons of water per day at home, says https://19january2017snapshot.epa.gov/www3/watersense/our_wa...

  300 gal/day * 365.25 days / year = 110,000 gallon per year

which means the average family isn't putting 1" of water on their 10K sq ft lawn per week.

Furthermore, the same source says "Nationally, outdoor water use accounts for 30 percent of household use", so that should be more like 33,000 gal / year on outdoor use.

It therefore seems like your estimate is off by quite a bit.

As an example adjustment for rain. Boston gets 3-4 inches of rain per month, so that's about 0.5 inches of extra watering needed per month, or 0.125 inches per week, or 1/8th of your estimate.

Fair enough.

But to the point of the original story: if electric cars become ubiquitous, firefighters are going to need to start using something besides plain water for car fire. Battery fires are Class B fires, and water isn't great for them. Strictly speaking, ICE car fires are Class B if the fuel and oil are taken into account. I wonder if the battery and associated components carry enough electricity to be considered "energized electrical equipment", which puts the fire into Class C territory.

In any case, I think a fully-equipped fire response for car fires is going to get more complicated.

No way.

4500 gallons = 600 cubic feet

600 cubic feet of water spread out over a quarter acre is .5 inches.

That's a moderate rain for roughly 45 minutes.

Looks like the avg pressure for a home is 2 gallons per minute. Watering your lawn for an hour would be 120 gallons.

You are wildly off.

Not in Arizona where the yards are rocks, which seems super ugly to me.

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