Electric Cars and Gear Ratios: An Unnecessary Requirement?

Electric cars do not need a variety of gear ratios like combustion engine cars. This article delves into the reason behind this, explains why electric motors require only one gear ratio, and explores the unnecessary concept of a transmission in electric vehicles.

The Role of Gear Ratios in IC-Powered Cars

Combustion engine (IC) cars rely on transmission systems to manage the engine's power output efficiently. The engine typically produces its maximum power within a specific range of revolutions per minute (rpm). To operate effectively, the driver must adjust the gear ratios to balance between low speed and high torque, and between high speed and low torque, based on the car's speed and road conditions. This ensures the engine stays within its optimal rpm range.

Why Electric Motors Require Only One Gear Ratio

Electric motors, on the other hand, produce power from 0 rpm to their maximum almost seamlessly. They can drive the wheels without the need for multiple gear ratios. The fundamental reason for this is that electric motors can generate torque at nearly any speed, making a single gear ratio sufficient for various driving conditions.

Retention of Transmissions in Electric Cars

Even in electric vehicles, some manufacturers retain existing transmissions for a few reasons. For instance, a conversion from an internal combustion engine (ICE) car to an electric car can sometimes benefit from keeping the transmission to simplify the conversion process. This is particularly beneficial in rear-wheel-drive models, where the transmission structure can be reused.

Transmission in Electric Cars Isn't Necessarily Necessary

While adding a transmission can simplify the conversion process, it also adds unnecessary weight, complexity, and costs. Modern electric motors, especially those with induction motor systems and synthesized-AC drives, have greatly reduced concerns related to low-speed operation at high power and related back-EMF issues.

High-Performance Electric Cars and Overdrive

For high-performance electric cars like the Porsche Panamera Hybrid and Porsche Taycan, the need for improved gear ratios is acknowledged. The Panamera Hybrid uses an 8-speed dual clutch gearbox between the motor and the wheels, even in fully electric mode. The Taycan features a two-speed rear axle to enhance performance and efficiency, particularly for very high top speeds.

These examples illustrate that while most electric cars do not need multiple gear ratios, high-performance electric vehicles benefit from specialized gear configurations to optimize performance and efficiency.

Conclusion

The evolving landscape of electric vehicle technology has led to a situation where most electric cars do not require a transmission system. Manufacturers and drivers must weigh the pros and cons of retaining traditional transmissions in electric vehicles to determine the most efficient and effective solutions for modern automotive design.