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Are electric cars fire hazards?

Volunteer

There seem to be a lot of reports about electric cars catching fire while charging, after striking a piece of road debris, or just sitting unplugged in the garage. Tesla has said that several of the fires with their vehicles were not related to the charging system. That may or may not be true but the car still burned down to ashes. A couple of homes have been totally destroyed but no one has burned to death as yet. Point is, maybe architects should think twice about putting bedrooms over a garage on a two-story house?

 
May 19, 17 4:38 pm
fictional\_/Christopher

the bedroom over the garage is be fire rated, 2hrs, so you have 2hrs to get out....

May 19, 17 5:08 pm
chickaletta

Is that code?

fictional\_/Christopher

depends.

Non Sequitur

^that.

May 19, 17 5:12 pm
fictional\_/Christopher

i imagine, surely could research it, but "combustion" engines with fuel tanks probably blew up a lot in the early days.....i know this from reading building code, specifically NYC 1938 building code which seperates out as a seperate category from all other Commercial (COM) uses the following" (5) Commercial buildings –
Garages, motor vehicle repair shops and gasoline selling stations." with regard to material (construction type), height, and area limitations

May 19, 17 5:40 pm
s=r*(theta)

Good question, I often think about these cell phone batteries overheating and exploding, imagine something like that happening in your hybrid or elec.!?!?

May 19, 17 5:51 pm
RickB-Astoria

In the early 1900, early garages intended for automobiles were usually required to be a detached structure made of non-combustible material... (CONCRETE). Other structures similar to garages either built into an existing house or as a separate structure was for carriage storage. A lot of those were at some point re-purposed for cars. 

As for electric cars, the danger is more a matter of type of batteries used. LiPo is your biggest risk. Li-on is not as risky but not completely the case. 

There could become options in the future for new batteries that are less fire risk. A 2-hr fire rated separation barrier and appropriate fire extinguishing setup maybe needed. Large LiPo or lithium batteries would probably require a lot of sand and dirt to sufficate the fire. Water suppression does not work very effective.

May 19, 17 6:26 pm
gwharton

Gasoline is actually very safe and stable in relation to its energy density (44 megajoules per kg). Liquid gasoline is actually not flammable. It won't burn unless it's in a vapor state mixed with oxygen. The whole "exploding gas tanks" trope is a hollywoodism, not something that actually happens without very unusual circumstances.

Batteries have a much lower energy density. One 10 gallon gas tank contains as much energy as 7 or 8 Tesla battery banks, which are much larger and weigh a lot more. Most batteries off-gas hydrogen, which is very flammable stuff and needs to be vented (a lot of boat fires start with battery banks). Higher-density battery technologies, such as the Lithium ion batteries used in most electronic devices and Teslas, push the limits of energy storage density with modern chemistry. By doing so, they run the risk of overheating and bursting into flames, even when not in use. In fact, Lithium-ion battery fires are so common that most airlines won't allow them to be checked as luggage anymore.

So, physics is working against electric vehicles on two fronts here:

  1. Unless there are massive, revolutionary developments in battery technology, batteries will never be as powerful as gasoline, and,
  2. Batteries are actually a lot less safe than gas tanks in cars.
May 19, 17 6:50 pm
RickB-Astoria

However, gasoline off-gases and the vapor is the greater danger but also consider octane level of the gasoline. However, I am not saying batteries are safer but the type of battery in question used in electric cars at this time do pose a particular risk and I do agree. Lead-acid and many other types of batteries do not have the same energy output/storage capacity of coloumb charge load capacity for it's weight & size ratio as the lithium batteries. There is a newer kind of cell/battery technology that I am curious about. A power cell with a long-term energy retention is what we typically call a "battery" but you know... a single AA battery is actually just a cell. Battery denotes multiple-cells in proper word use. Note: the key word.... cell must be there when you are talking about a single cell. In the case of photovoltaic cells, it's not usually useful as a battery because it does not retain the electrical charge. I am curiously looking at the concept: https://www.youtube.com/watch?v=ghQZ1Wtj9hc and https://www.youtube.com/watch?v=K-PkoJrs5n8 and where things could go with the technology.

RickB-Astoria

At this stage, I doubt it is ready for use in full electric cars. At least not at this time. If there is a means of implementing some level of continuous load for being able to hold enough charge capacity to drive a car at least for the time during night at any speed from city stop & go lower speed driving to highway speed. It can be interesting nonetheless. I do see this tech to be particularly interesting for home and building design. I see this technology being of particular interest for solar based building design.

mightyaa

The whole "exploding gas tanks" trope is a hollywoodism, not something that actually happens without very unusual circumstances.

Suggest you google Ford Pinto.. that one was notorious because not only did the gas tank rupture at a low speed rear end, but the body buckled and jammed the doors shut.  Also it was a known design defect that could have been solved for very little money.  There have been instances of electric cars burning.  Gas cars burn too, steam engine boilers have exploded, SUV's have flipped, air bags deploying while driving, cars that accelerate without driver input, cars that slip out of gear and roll, etc.  

Basically... define "safe" and it doesn't mean you won't find exceptions.  btw; there is also a video of a idiot driving a Tesla through a flooded tunnel.... 

May 22, 17 12:54 pm
RickB-Astoria

mightyaa, 

While the Ford Pinto did have a relative weak spot hey didn't really go *BOOM* by just a little ding to the bumper like in the Top Secret! film. It was because of this: https://www.youtube.com/watch?v=x43ixEeh4b0 or https://www.youtube.com/watch?v=-9GGDOUDLhc and some other programs and TV commercials that depicted it that a Pinto would go *boom* with just in a slight tap of the bumper. In reality, it took more than just a little *ding* to the bumper. You actually had to have a rear end collision. In fact, you had to be rear ended with a vehicle at some speed.

https://www.youtube.com/watch?v=_stpBzOAcWw

Here, a Pinto is rear ended by a Impala at 35 MPH. If anything were to hit your gas take at some speed, there's a chance it would combust.

Most of the Pintos would have the upgrades made and later model Pintos (after '78) would have safer fuel system. Again, there is one inherent factor of safety that did come out of it for the Pinto driver, the idea of just a slight ding of the bumper would result in a big explosion meant if you were driving a Pinto, you would have fewer people riding up close behind you so the risk of a rear-end collision was significantly lower and also when you park on the street, you would likely not find as many people parking in the parking space behind your Pinto. Now, this might not register in the minds of the young kids who didn't even grow up in those times so you still have that risk.

It wasn't quite as bad as the PR damage was but it was something that would warrant being sure you have the fuel tank setup reinforced with a reinforced bumper and all the safety measures that goes with it to improve the safety of the Pinto while doing so in a way that doesn't appear outward to the public that you did the upgrades so you can still enjoy driving without as many people tailgating you. 

May 22, 17 1:21 pm
mightyaa

Why choose this Rick?..  

Some of the damning evidence is that Ford conducted it's own low speed rear impact (20 mph).  9 out of 11 of the test cars had the fuel tank rupture and several of them caught fire, so Ford knew there was a problem.... So... um... should you avoid small cars and only drive land yachts?  Tell me small car safety isn't still a concern and the PR damage was just to the Pinto....

The point was.... Safety is a relative term and there are multiple incidents of fatalities due to faulty design / engineering.  Just because there have been a handful of incidents, it doesn't remotely mean a entire technology is unsafe... however I wouldn't suggest traveling by being shot out of a cannon; the clown makeup alone doesn't justify the time savings.  

May 22, 17 3:00 pm
Beehelp

There are inherent risks when you store enough energy to propel a two-ton car at 75 miles an hour for hundreds of miles. After all, thousands of gasoline-powered cars catch fire in collisions each year. In principle, those risks can be managed through structural design and cooling. But could the lithium-ion battery cells themselves be made safer?

Jun 12, 17 10:38 am
Volunteer

Some model Jeeps have had their gas tanks explode on impact also. One instance was on an Interstate near me a couple of years ago where several people were burned to death. The gas tank was located well aft of the rear axel on this model. The auto company was evading and prevaricating when a credible eyewitness came forward and said she saw everything and would be happy to testify in court. They settled quickly after that.

Jun 12, 17 11:58 am

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