Electric cars represent a fundamental change in drivetrain architecture. Using motors instead of an internal combustion engine greatly simplifies car design. So do Electric cars have gears like a regular car?
The large majority of electric cars have no gears or a transmission. However some do, such as the Porsche Taycan.
The reason gear boxes are not required on electric cars is the due to the nature of electric motors. Motors are able to produce a tremendous amount of torque at very low RPM. That torque does not drop off significantly as the revolutions of the motor increases.
Tesla’s drive motor for example can spin up to 18000 RPM, while maintaining suitable torque through out that range. Although it does start to drop over 6000 RPM. This allows the motor to be coupled directly to the car.
The car is able to accelerate quickly due to high torque at low RPM and achieve highway speeds at higher RPM’s where less torque is required. Essentially the motor is able to propel the car from zero to top speed using only it’s available rev range.
Why do regular cars need gears?
A gasoline engine works quite differently than an electric motor. Engines have a much narrower power and torque range. The average engine does not begin to make it’s highest rated torque and horsepower numbers until higher in the rev range. Engines also spin at a lot lower maximum RPM than an electric motor can. My S2000 for example has one of the highest redlines ( Maximum engine RPM ) of any production car at 9000 RPM. Which is only half of what the Tesla Motor can do.
Gears are required to keep the engine rotating at it’s optimal speed to create the required amount of power to move the car at wide range of road speeds. Having such a limited RPM and power range means that gears are required to give the car a mechanical advantage.
First gear will give the car a lot of initial thrust but the engine will then start to rev too high before you have reached your desired speed. So you select second gear and do that same process over again until you reach your desired speed and to conserve fuel economy drive at the lowest RPM possible.
Do any Electric Cars have gears?
Yes, the Porsche Taycan has a 2 speed gearbox. Stephan Demmerer, who runs ZF’s E-Mobility engineering division says “For automakers willing to take on a bit more complexity, the two-speed setup can either improve an EV’s range by 5 percent, or push its top speed beyond the typical cap.”
Essentially Porsche has decided to implement multiple gears to increase efficiency and increase top speed.
The original Tesla Roadster also had a 2 speed gearbox. This car you may remember as the electrified Lotus Elise. Certainly ahead of its time.
As electric car companies continue to try and differentiate them from the rest, perhaps gear boxes will become more common place. The argument could be made that they do provide some benefit.
In the mean time I don’t hear too many complaints about performance.
Oh and it’s one of the reasons that they don’t need oil either. You can read about that over here!