The Efficiency Engineer: Optimizing Electric Vehicles

Introduction

Designing a high-performance electric vehicle (EV) is a “wicked problem.” If you increase the battery size to get more range, the car becomes heavier, which reduces efficiency. If you make the car larger for more passengers, air resistance increases. Engineers must solve these complex problems by breaking them down into smaller sub-problems. In this task, you are the Lead Efficiency Engineer for a new logistics company. Your mission: Design an EV capable of traveling 550 km on a single charge at a cruising speed of 100 km/h.

Part 1: Engage

Look at the Design Parameters in the simulation. We have many variables to control.

Initial Analysis Questions:

  1. List three variables that you think will decrease the vehicle’s range if their value is increased.
  2. Which variable do you think is the most “expensive” to increase (in terms of weight or cost)?
  3. The Sub-Problem Strategy: To solve the 550 km range goal, we can break it into three sub-problems:
    • Sub-Problem A: Minimizing Air Resistance (Drag)
    • Sub-Problem B: Minimizing Rolling Resistance (Friction)
    • Sub-Problem C: Balancing Energy Storage (Battery)

Part 2: Explore

Open the Electric Vehicle Optimization Simulation. Use the “Record Trial” button to log your data.

Sub-Problem A: Aerodynamic Efficiency

  1. Set Battery to 60 kWh, Mass to 1500 kg, and Speed to 100 km/h.
  2. Keep all other variables constant. Change the Drag Coefficient (Cd) from 0.15 to 0.50 in steps of 0.05.
  3. Record the Efficiency (Wh/km) for each. Which Cd value allows for the best range?

Sub-Problem B: The Weight Penalty

  1. Set Drag to 0.25 and Battery to 60 kWh.
  2. Increase the Base Mass from 800 kg to 2500 kg.
  3. Observe how the Total Mass changes as you increase the Battery Capacity. How much mass does a 120 kWh battery add compared to a 20 kWh battery?

Sub-Problem C: The Speed Factor

  1. Pick your “best” vehicle design so far.
  2. Test the range at 60 km/h, 100 km/h, and 140 km/h.
  3. How does high-speed travel impact your efficiency? Use the Power Loss Breakdown chart to see which force becomes dominant at high speeds.

Part 3: Explain

  1. Interconnectedness: Explain why adding a larger battery doesn’t always result in a linear increase in range. Use the “Total Mass” and “Efficiency” metrics from your data to support your answer.
  2. Trade-offs: If you were forced to use a less aerodynamic body (Cd = 0.40), what specific design changes would you make to other parameters to still achieve a 500 km range?
  3. System Modeling: Based on the “Power Loss Breakdown” chart, which system (Aerodynamics, Rolling, or Accessories) should engineers focus on most if the car is primarily used for slow city driving? What about fast highway driving?

Part 4: Elaborate & Evaluate

The Final Design Challenge: Design a vehicle that meets the following Criteria and Constraints:

Your Solution:

  1. List your chosen parameters (Battery, Cd, Area, Crr, Mass).
  2. Provide your final Range and Efficiency data.
  3. Justification: Write a short rationale for your design. How did you prioritize certain criteria (like weight vs. battery size) to achieve the goal? Explain how you solved the sub-problems to meet the final requirement.