Published on April 1st, 2018 | by Nicolas Zart0
Do Electric Vehicles Have Better Overall Safety? Part 2
April 1st, 2018 by Nicolas Zart
In the first part of our series on whether or not electric vehicles (EV) are safer than comparable gasoline cars, EVs seem to beat traditional cars at least on paper in terms of drivetrain layout freedom. Given that the overall appearance of electric cars typically isn’t a dramatic departure from gas/diesel vehicles, normal people probably have no idea how this new vehicle layout can be so different, but it can. We’re going to look at another aspect of electric cars’ greater flexibility and superior design in this piece — structural benefits.
Today’s Electric Cars Are Like Today’s Gas Cars, Except Better
Most BEVs are structurally safer than conventional cars. Overall, they have fewer components needed to run the car, meaning less wear and tear and less space used within the infrastructure of the vehicle. This allows a rethink of some of the safety features we take for granted today and puts ICE cars at a disadvantage. There is little layout “elbow room” in an ICE drivetrain, but an electric car’s motor(s) can be placed in various locations (as indicated in part 1) and so can the batteries.
For the purposes of this discussion, a BEV is a vehicle designed from the ground up to run completely on electricity stored in a battery, a vehicle with no onboard range extender systems. It is electric only and only uses electricity as its means of energy — period. We are talking about a Chevy Bolt, not a Chevy Volt; and a BMW i3, not a BMW i3 REx. The reason in part is that, in this case, the space saved from not having internal combustion engines and related components is what makes EVs better. When you don’t have to pack that stuff in front of, behind, under, and around the driver and passengers, you have more freedom to protect them from various threats.
In the US, the National Highway for Testing Safety Administration (NHTSA) shows that in 2016 there were 37,461 people killed in 34,436 motor vehicle crashes for an average of 102 deaths per day. Around 90% of those fatalities are “in-vehicle” casualties. Approximately 174,000 gas/diesel cars go up in smoke every year in the United States, according to the National Fire Protection Association (NFPA). EV fires have been almost nonexistent compared to the number of fires that occur in gasoline cars. There was one fire death in a Tesla Model X recently — just one — and it resulted in numerous headlines and apparently an National Transportation Safety Board (NTSB) investigation. Indeed, even one death is a tragedy, but 1 vs. 37,461 is a big difference. Furthermore, one or a few EV fires doesn’t compare to 500,000 gas/diesel car fires per year, even if we were to make the figures proportional to number of cars on the road.
Notably, vehicle safety has been improving, and we see the results of that in fewer deaths per capita and per mile of travel, but EVs offer an even further improvement, and we’ll explain why.
According to How Safe Is Your Car, an Australian crash safety website, the key components of good crash safety design are:
- Strong occupant compartment: “The cabin of the car should keep its shape in frontal crashes to protect the driver and passenger spaces. The steering column, dashboard, roof pillars, pedals and floor panels should not be pushed excessively inwards, where they are more likely to injure drivers and passengers. Doors should remain closed during a crash and should be able to be opened afterward to assist in the quick rescue, while strong roof pillars can provide extra protection in rollover crashes.”
- Side impact protection: “Increased side door strength, internal padding, and better seats can improve protection in side impact crashes. Most new cars have side intrusion beams or other protection within the door structure. Some cars also have padding on the inside door panels.”
- Crumple zones: “Modern cars protect drivers and passengers in frontal, rear and offset crashes by using crumple zones to absorb crash energy. This means that the car absorbs the impact of the crash, not the driver or passengers.”
Sticking the bulk of a car’s powertrain under the car (as can be done with BEVs) opens up interior design space. Electric cars — if designed well with this in mind — add a lot to key crumple zones. The most famous example of this is the frunk of the Tesla Model S and Model X. It is a trunk in the front of these vehicles where the engine would normally be. Aside from extra storage capacity, it is basically a large extra crumple zone. While not as large as the frunks in the Model S and Model X, some other electric cars have frunks as well. Even for those that don’t, the electric motors and other devices located under the hoods of electric cars almost never take up as much space as the engines of gasoline/diesel cars, thus resulting in more crumple space under the hood.
Getting back to design freedom, it should be noted that batteries could be stuffed under hoods where engines are, but more logical and common is to stick the battery pack on the bottom of the car, leaving more empty space and carefully planned crumple zones into the front and back of the car at the height of the humans sitting inside.
Of course, the lower center of gravity from sticking batteries under the floor of the car also improves handling and prevents rollover accidents, but that’s a topic we’ll come back to in a coming article.