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Comment by samatman | Hacker News Reader

I'm not really seeing a scenario where an out-of-control car fire has worse results in a garage for gasoline vs. lithium ion.

In both cases it's an absolutely massive thermal conflagration, with no hope of putting it out using anything a homeowner has on hand, and it will proceed so rapidly that the house is going to be totaled by the time the fire department shows up.

I have to figure this is just bias toward the familiar. I will grant you that I don't refill an ICE car inside my own garage, so maybe charging genuinely makes the electric more dangerous. But it probably doesn't do so in fact, I would guess in both cases the biggest risk is something like leaving rags soaked in linseed oil and getting spontaneous combustion.

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This is a good discussion on StackExchange about the fire risk of Li-Ion batteries:

https://electronics.stackexchange.com/questions/230155/why-i...

Many newly built homes have automatic sprinklers - capable of containing and localizing the damage from fires.

A sprinkler system running on regular water supply pressure is not going to put out a lithium ion fire.

This is not common by any stretch. I have never seen a residential home with automatic sprinklers, only commercial real estate and apartments. The cost is prohibitive, and in many climates (where freezing is a norm) would be useless in garages.

California is a big EV market. Sprinklers are required in new construction in CA.

https://www.nahb.org/-/media/NAHB/advocacy/docs/top-prioriti...

Your link shows that 48 out of 50 states don't require sprinklers. I would guess that less than 5% of SFR in the US have sprinklers.

>Your link shows that 48 out of 50 states don't require sprinklers.

Partial Mandate: NY, Mass Full Mandate: CA, Maryland

Those are 2 big states in there. By population the four are ~73 million, or a fifth of America.

Massachusetts only requires them in townhomes and houses over 14K square feet. In other words mansions. NY only requires them in three story buildings, otherwise it's up to the buyer. So these are nonsense arguments. Considering how many existing houses are exempt from all of this, I would estimate that less than 10% of the homes in CA have them, and less than 2% in these other four states.

All post 2018 construction in my area (including single family residential) is required to have automatic sprinklers).

The cost is absolutely not prohibitive, it's about $1-2/sq ft in a new home or $5-6/sq ft if you're retrofitting an old home[1]. For a new 2000 sq ft house that would be around $4000 dollars. Probably <1% of the overall house value given recent housing prices.

[1] https://www.bobvila.com/articles/465-residential-sprinkler-s...

This would depend on house prices. Where I live, you can buy a 2000 sq ft house for $300K or less. That's 1.3% increase in price to add sprinklers, and I would wager that 99% of homeowners would prefer not to spend $4K on this.

This is true.

I mean, it's also true that water will not put out a gasoline fire, only spread it around and make it worse.

But what you said is true also.

I haven't heard of any ICE engines spontaneously combusting. I have heard of many lithium batteries, primarily in phones, combusting. We're better at keeping gasoline safe than charged electrical energy.

Electrical fires regularly kick off gasoline fires in ice vehicles.

When I was a kid in the early 90s our family car caught fire while parked in the driveway and turned off.

It'd been parked for an hour or two, and the trigger was something electrical in the engine cavity.

They are fairly common. 233,300 fires and 329 deaths per year in the US according to http://www.nfpa.org/news-and-research/fire-statistics-and-re...

That covers the number of times vehicles have caught fire. It doesn't reference the cause (e.g. spontaneous combustion vs. as a result of a crash).

I personally have had the car I was driving catch fire spontaneously. Once I was inside, once nearby. Funny thing, same car, different causes.

I'm glad you got out safely. Judging by all the replies it's far more likely than I guessed. I've been lucky.

The NFPA has data on that too. Fire causes are:

- 47% mechanical

- 21% electrical

- 7% intentional

- 6% exposure

- 4% crash, overturn, run-over

- 2% smoking

So crashes are a relatively rare cause. They also break it down by the area the fire started:

- 63% engine area, running gear, or wheel area

- 11% passenger/operator area

- 5% cargo/trunk

- 3% exterior

- 2% fuel tank or line

Interpolating between those numbers, you might guess that between 20% and 40% of fires could be described as "engine spontaneously combusting." That would be 45,000 - 90,000 per year in the US.

So despite you never having heard of it, it does happen.

[0] https://www.nfpa.org/vehiclefires, numbers above from report table 8 & 9

Thanks for finding that data. That's interesting. I'm amazed that that happens, because absent people bringing it up when talking about Tesla I've never really heard that before.

Most interesting is that the first part of an ICE to catch on fire is most frequently the electrical wiring. And even if it is a flammable liquid (the second most likely cause), it's only a 42% chance that liquid was gasoline!

Thanks again, it's interesting reading.

Likely the reason you’ve never heard of car fires before is that they are so common that they are not news.

FWIW, a friend's Aston Martin V8 Vantage spontaneously combusted in front of his house a few years ago. Car was a total loss and took the insurance and manufacturer months to sort out who was liable for damages (fortunately, just replacement of the car - no other cars were parked nearby, and friend kept it in the street).

My friends house burned down due to a car fire inside his garage. The engine didn't spontaneously combust (any more than the Tesla power-ask in the article), but having a car in a garage does pose some risk.

I had a friend whose block heater shorted out while the car was in his garage. He was alerted by a smoke detector, went out in his PJ's, opened the garage door, and pushed the car outside, whereupon it burst into a pillar of flame.

He noticed significant tingling in his feet while pushing the car out. This was in the days before GFCIs. He's lucky he wasn't electrocuted.

Cars have stopped catching on fire nearly as often since GFCIs were introduced. My guess is that is coincidence.

You've never heard of any ICE car spontaneously combusting? You must not follow any car recalls, tons of cars have been recalled in the past due to fire risks.

https://www.caranddriver.com/news/a35782883/kia-cadenza-spor...

https://www.autosafety.org/ford-ignition-switch-fires/

https://www.mlive.com/news/2021/03/2021-ram-truck-owner-enco...

https://www.industryweek.com/operations/safety/article/21963...

https://www.auto123.com/en/news/gm-recall-risk-of-fire/61360...

ICE vehicles can have strange failure modes leaking flammable fluids places where they should go where its really hot. Sometimes this gets mixed with a spark from a bad electrical connector, sometimes it drips on something hot.

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