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  • May 7, 2020

  • 6 min read


Electric cars and safety

Contrary to a common belief which is purported in certain sections of the media, electric cars really are super safe. The way most electric cars are designed now (which, admittedly, wasn't always the case) means they’re conceptualised from the ground-up, with some of the newest safety technology already in place rather than being shoehorned into older systems.

The standard safety system for vehicles is the Euro NCAP safety tests. These tests represent, in a simplified way, real-life vehicle accident scenarios that could result in injuries or deaths. Each car that undergoes these tests receives a star rating out of 5. Of the major electric vehicles, the vast majority have attained a 5-star rating (this mirrors the general theme of automotive development, as cars, in general, are getting increasingly safer).

Electric motors and batteries change the way manufacturers have looked at building vehicles. Firstly, you don’t need to design around a lump of metal that’s a certain size and shape (aka “an engine”) and that needs to be placed in an area of the vehicle. Traditionally the engine in front of the driver, which is why cars have long bonnets (with some notable exceptions, like the Porsche 911 which houses its engine over the rear wheels). Internal combustion engine cars have had to design around the fact that engines get hot and can cause things to catch fire, designers have had to dictate a lot of the design process to where to put FIREWALLS and how to safely route fluids (*ie fuel) and wiring which really don’t cope well with getting hot.

A FIREWALL is a bit of a scary word for a piece of metal between the thing that can catch fire, and something the manufacturer wants to stop from going on fire. (This is where the computing term comes from, etymology fans). So, you’d place a FIREWALL between the cabin and the engine, and between the fuel tank and everything else.

We need to remember that petrol is highly flammable and volatile. Fires still happen, there are about 100,000 vehicle fires a year in the UK. This is through misuse of petrol pumps, crashes, hot things coming into contact with petrol and many other reasons but most of these are from cars being inverted.

The placement of the engine in the front of the car also leads to there being a lack of a crumple zone, or at least means that the crumple zone needs to be smaller. In an accident you want to dissipate energy, which is why Formula One cars blow themselves into lots of little tiny pieces when they crash, each piece of the car that comes off takes a little bit of energy with it effectively making the crash last longer and therefore decreasing the pressure / force on the driver.

Electric cars have two huge advantages in these situations

-The heavy piece in an electric car is the battery. Most manufacturers sit that along the floor of the car creating a really low and solid platform. This gives them low centres of gravity, making them very hard to roll onto their roofs. This keeps the car flat and with a much more even weight distribution (how much weight is over each set of wheels) and is much closer to 50/50 than most other petrol or diesel vehicles. This by and large stops them from rolling. Even if they were to roll, they should be much safer because there isn’t flammable fluid (for instance, petrol) that could leak out.

-The other advantage electric cars have is crash structures. The space on a typical car where an engine would be found is filled with clever tech to dissipate all the unwanted force of a frontal impact. An electric car uses the strength of the battery to absorb a side impact, because you don’t want the side of the car crumpling into the survival cell. (the space in which the humans in the car need to have to stay safe)

Believe it or not the car is supposed to look totalled after a crash, as it’s designed to take the impact and absorb that force. But in a side impact you don’t want intrusion. So in a side impact the battery is used as a stress plate, and the car stays strong.

Finally lets talk about the elephant in the room: fire. Most reports relating to EV safety are around fire; particularly how they seemingly spontaneously burst into flames. If you google certain words (like “thermal runaway”), you may see certain scary photos and videos of electric cars.

Thermal runaway is when a battery just gets hotter and hotter. It is really hard to stop, but it also takes a long time to occur, this gives plenty of time to vacate the vehicle. Certain reports would have you believe this happens in most electric cars. Don’t be fooled. This is a huge misrepresentation of the numbers of electric cars on the market. On average in the USA 4% of all petrol cars end life on fire. That is a significant proportion (but, given the reasons outlined above, understandable). *From 2012 – 2018, there has been approximately one Tesla vehicle fire for every 170 million miles traveled. By comparison, data from the National Fire Protection Association (NFPA) and U.S. Department of Transportation shows that in the United States there is a vehicle fire for every 19 million miles traveled.

Finally, although by no means a scientific argument, consider this: Renault have built over 50,000 all-electric Zoes and not a single one has gone on fire. Why? The electric car’s trump card! Because they have a big lump of non-flammable electricity running the car, rather than a highly flammable liquid stored right next to a big burny hot thing that uses fire to push the car forward.

If you want to learn more about electric cars, or ask us any questions, please do drop us a note at hello@octopusev.com or give us a call on 020 3870 3892.