Why Has No Production Car Hit 300 MPH? Electric Cars

Why Has No Production Car Hit 300 MPH? Electric Cars


Hello everyone and welcome! This is the fourth of a Five-Part Series where I have partnered with Formula E to talk about electric car technology and in this video we’re answering the question could an electric production car be the first to hit 300 mph. Now the premise for this video stems originally from an older video I did asking the question “Why has no production car ever hit 300 miles per hour?” And in this video we learned a big part of why cars haven’t hit this 300 mph mark is because of the drag, the aerodynamic drag placed on the vehicle. And with internal combustion engines you need a lot of cooling, and that cooling means you need additional drag because you have to pass air through the vehicle. And so a lot of people in the comments asked you know “Would It be easier to achieve this 300 mph goal using an electric car?” Because they’re far more efficient and then perhaps they wouldn’t have that aerodynamic drag because they wouldn’t need as much cooling. So that’s what we’re going to discuss in this video. Now as was discussed in the previous video this is our equation for power, how much power we will need to reach a certain speed. That’s being V for velocity here in this case 300 mph. Now you have to break this down into three different sections. Here we’ve got drag, rolling resistance, and your drivetrain efficiency. But The biggest part of what’s going to cause you to need a lot of power to reach a high speed is aerodynamic drag. And so If you look at this equation right here the most critical component is this coefficient of drag multiplied by the front surface area of your vehicle. Because as you can see it’s multiplied by V squared and V. So you have to multiply the coefficient of drag by the frontal area of the car by velocity cubed. So as speed gets higher the amount of energy you need to overcome that aerodynamic drag goes up by velocity cubed, so obviously it’s extremely important to minimize the coefficient of drag in the frontal surface area to keep this number right here low so you don’t need all that much power. Now with internal combustion engines, this coefficient of drag is heavily influenced by the cooling system because you need all of that extra air to cool down you know the engine, the transmission, things like that, and so could you know an electric vehicle have an advantage in this scenario?
And one of the interesting things to think about and something that’s not often thought about when comparing these two systems is the fact that internal combustion engines operate at a pretty high temperature. So about 200° Fahrenheit or about 95°C Versus electric vehicles, i’ve actually worked on a cooling system for an electric vehicle and for some of the components they were allowed to get up to 60°C, for some of the other components they were allowed to get up to 65°C in Formula E you really don’t want your battery temperatures exceeding 62°C. So we’re just going to say that our maximum coolant temperature here is about 60°C. Now if we have the same exact size radiator and we have ambient air at 20°C, passing through that radiator you can tell that you’re going to reject a lot more heat with this radiator than with this one even though they are exactly the same, and the reason being is because your temperature differential between Your inlet coolant which is 95 versus your ambient air Which is 20 so about 75°C here, Versus 60 going in the inlet for your electric vehicle 20°C ambient air means you only have a temperature delta of 40°C so this is going to reject a lot more heat, this isn’t going to reject as much heat, and these kind of play you know to balance out because the internal combustion engine needs to reject more heat it’s far more inefficient so it has a lot more heat to reject but it’s better at rejecting that heat because it operates at a higher temperature. On the flip side the electric vehicle has less energy to reject because it’s far more efficient but it’s more difficult to reject that heat, because the temperature delta between ambient air and the coolant going Into your radiator is going to be lower. And when I was developing a cooling system for an electric vehicle what I noticed is that I was using basically the same sized radiators as our internal combustion equivalent vehicles were using, even though we were using an electric vehicle that was far more efficient. Now let’s dive a little more into the cooling systems on Formula E cars and these have two separate cooling circuits. The radiators will be housed in the side pods of the vehicle and you’ll have one cooling circuit for the battery, one for the motor and the inverter. And actually because you know Formula E races are relatively short and they switch cars halfway through so you know we’re thinking about 45 minutes to an hour somewhere in that range of time that these races last and only that in one car they actually don’t cool their transmissions because they can get away with it you know it’s only running out there maybe 25 or so minutes, and as a result it’s not going to get hot enough in that duration. It’s efficient enough that they don’t have to worry about It and they can run out there. Of course some teams are only using one gear so it’s even less of A concern you know not as much moving components in there, but regardless they don’t actually have to cool their transmissions since the duration of that run is relatively short. They do of course have to cool the battery and the motor and inverter and one of the challenges they run into is that this battery cannot exceed 62°C or they start to get reduced performance of their vehicle and so there are races in which Formula E goes of course all around the world where their air temperatures are as high as 32°C so remember this temperature differential is getting smaller and smaller and so what that means is this cooling circuit is less and less effective at rejecting that heat and so when they do run in scenarios where ambient temperatures are so high you know some of the strategy changes they have to make they have to reduce the amount of regen that they use, because that regen is putting heat back into the battery pack and ultimately if you know reducing regen isn’t enough they will have to limit throttle if the cooling system isn’t capable of rejecting all that heat the first thing of course you want to do is reduce regen but if that’s not quite enough then you would go into you know scenarios where you want to lift and coast and maintain energy in that battery and not get it too hot. So going back to our original question, ‘Will an electric production car be the first to hit 300 mph?’ It’s really not any less of a challenge than it is for internal combustion engines and reason being is because you’re still going to need significant cooling as a result of those lower coolant temperatures which will influence your coefficient of drag and that means you know ultimately you’re going to need similar power levels as an internal combustion engine to reach those high speeds that said it does have an advantage from an energy standpoint internal combustion engines throw about a third of their energy out the exhaust another third of that energy just into heating the coolant surrounding the engine block wasted as heat and then a third of that you know turning eventually into useful work of course you have those drivetrain losses, but much less efficient than using an electric car. So the electric car will need less energy but It will still need very close to the same amount of power if not the exact same amount of power in order to achieve something like this. So thank you all for watching if you have any questions or comments deel free to leave them below. be sure to check out Formula E’s channel, they’ve got all kinds of neat information about how these electric cars work that kind of thing and i’ll also include links to the previous videos of this series which I made, hope you enjoy them thanks for watching!