Battery capacity (kWh) and range relationship in EV Technology - Mini Project: Build & Apply

Battery Capacity (kWh) and Range Relationship

📖 Scenario: You are learning about electric vehicles (EVs). One important factor is how the battery capacity in kilowatt-hours (kWh) relates to the driving range in kilometers (km). Understanding this helps people choose the right EV for their needs.

🎯 Goal: Build a simple data set that shows battery capacities and their corresponding ranges. Then, calculate the average range per kWh to understand how battery size affects driving distance.

📋 What You'll Learn

Create a dictionary called battery_data with exact entries for battery capacity (kWh) as keys and range (km) as values.

Create a variable called total_capacity initialized to 0 to hold the sum of battery capacities.

Use a for loop with variables capacity and range_km to iterate over battery_data.items() and sum the capacities into total_capacity.

Create a variable called average_range_per_kwh that divides the total range by the total capacity.

💡 Why This Matters

🌍 Real World

Understanding battery capacity and range helps consumers choose electric vehicles that fit their daily travel needs.

💼 Career

Knowledge of battery performance metrics is important for EV sales, maintenance, and design roles.

1

Create battery capacity and range data

Create a dictionary called battery_data with these exact entries: 40: 240, 60: 360, 75: 450, 90: 540.

EV Technology

# Create the battery_data dictionary with capacity as keys and range as values
# Your code here

Hint

Use curly braces {} to create a dictionary with keys as battery capacities and values as ranges.

2

Initialize total capacity variable

Create a variable called total_capacity and set it to 0 to start summing battery capacities.

EV Technology

battery_data = {40: 240, 60: 360, 75: 450, 90: 540}
# Initialize total_capacity to 0
# Your code here

Hint

Set total_capacity to zero before adding values.

3

Sum battery capacities using a loop

Use a for loop with variables capacity and range_km to iterate over battery_data.items(). Inside the loop, add capacity to total_capacity.

EV Technology

battery_data = {40: 240, 60: 360, 75: 450, 90: 540}
total_capacity = 0
# Use a for loop to add capacities
# Your code here

Hint

Use for capacity, range_km in battery_data.items(): and add capacity to total_capacity inside the loop.

4

Calculate average range per kWh

Create a variable called average_range_per_kwh that divides the sum of all ranges by total_capacity. Use sum(battery_data.values()) to get total range.

EV Technology

battery_data = {40: 240, 60: 360, 75: 450, 90: 540}
total_capacity = 0
for capacity, range_km in battery_data.items():
    total_capacity += capacity
# Calculate average_range_per_kwh
# Your code here

Hint

Use sum(battery_data.values()) to get total range and divide by total_capacity.

Practice

1. What does the battery capacity measured in kWh represent in an electric vehicle (EV)?

easy

A. The speed at which the EV can travel

B. The weight of the battery

C. The total amount of energy the battery can store

D. The time it takes to charge the battery fully

Solution

1. Step 1: Understand battery capacity meaning

   Battery capacity in kWh shows how much energy the battery can hold at full charge.

2. Step 2: Differentiate from other factors

   Speed, weight, and charging time are different characteristics, not battery capacity.

3. Final Answer:

   The total amount of energy the battery can store -> Option C

4. Quick Check:

   Battery capacity = energy stored [OK]

Hint: Battery capacity means stored energy, not speed or weight [OK]

Common Mistakes:

• Confusing capacity with charging time
• Thinking capacity means battery weight
• Mixing capacity with vehicle speed

2. Which formula correctly relates battery capacity (kWh), energy efficiency (kWh per mile), and driving range (miles)?

easy

A. Range = Battery capacity x Energy efficiency

B. Range = Battery capacity ÷ Energy efficiency

C. Range = Energy efficiency ÷ Battery capacity

D. Range = Battery capacity + Energy efficiency

Solution

1. Step 1: Understand units and relationship

   Energy efficiency is how many kWh are used per mile, so dividing capacity by efficiency gives miles.

2. Step 2: Apply correct formula

   Range (miles) = Battery capacity (kWh) ÷ Energy used per mile (kWh/mile).

3. Final Answer:

   Range = Battery capacity ÷ Energy efficiency -> Option B

4. Quick Check:

   Range = Capacity ÷ Efficiency [OK]

Hint: Divide capacity by efficiency to get range [OK]

Common Mistakes:

• Multiplying capacity by efficiency instead of dividing
• Adding capacity and efficiency
• Reversing the division order

3. An EV has a battery capacity of 75 kWh and an energy efficiency of 0.25 kWh per mile. What is its approximate driving range?

medium

A. 300 miles

B. 18.75 miles

C. 75 miles

D. 0.0033 miles

Solution

1. Step 1: Identify given values

   Battery capacity = 75 kWh, Energy efficiency = 0.25 kWh/mile.

2. Step 2: Calculate range using formula

   Range = 75 ÷ 0.25 = 300 miles.

3. Final Answer:

   300 miles -> Option A

4. Quick Check:

   75 ÷ 0.25 = 300 [OK]

Hint: Divide 75 by 0.25 to get 300 miles range [OK]

Common Mistakes:

• Multiplying instead of dividing
• Confusing units and calculating incorrectly
• Choosing the smallest number thinking it's correct

4. A student wrote this formula to calculate EV range: range = battery_capacity * energy_efficiency. What is wrong with this formula?

medium

A. It should multiply battery capacity by the square of energy efficiency

B. It should add battery capacity and energy efficiency

C. The formula is correct as is

D. It should divide battery capacity by energy efficiency, not multiply

Solution

1. Step 1: Recall correct formula for range

   Range equals battery capacity divided by energy used per mile, not multiplied.

2. Step 2: Identify error in student's formula

   Multiplying capacity by efficiency gives wrong units and wrong result.

3. Final Answer:

   It should divide battery capacity by energy efficiency, not multiply -> Option D

4. Quick Check:

   Range = Capacity ÷ Efficiency, not x [OK]

Hint: Range = capacity ÷ efficiency, not multiply [OK]

Common Mistakes:

• Using multiplication instead of division
• Assuming formula is correct without checking units
• Adding values instead of dividing

5. You want an EV that can travel at least 250 miles on a single charge. If the car's energy efficiency is 0.3 kWh per mile, what minimum battery capacity (in kWh) should you look for?

hard

A. 75 kWh

B. 83.33 kWh

C. 250 kWh

D. 0.0012 kWh

Solution

1. Step 1: Understand the requirement and formula

   Range = Battery capacity ÷ Energy efficiency. Rearranged: Battery capacity = Range x Energy efficiency.

2. Step 2: Calculate minimum battery capacity

   Battery capacity = 250 miles x 0.3 kWh/mile = 75 kWh. But check options carefully.

3. Step 3: Recalculate carefully

   250 x 0.3 = 75 kWh, but 83.33 kWh is 83.33 kWh, 75 kWh is 75 kWh. The correct minimum is 75 kWh.

4. Final Answer:

   75 kWh -> Option A

5. Quick Check:

   Capacity = Range x Efficiency = 75 kWh [OK]

Hint: Multiply range by efficiency to find capacity [OK]

Common Mistakes:

• Dividing instead of multiplying
• Choosing wrong option due to calculation error
• Confusing range and capacity units