Charging time calculation in EV Technology - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the formula to calculate charging time in hours.

EV Technology

charging_time = battery_capacity [1] charging_power

Drag options to blanks, or click blank then click option'

A/

B*

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication instead of division.

Adding or subtracting values which does not give time.

The charging time is calculated by dividing the battery capacity (in kWh) by the charging power (in kW).

2fill in blank

medium

Complete the code to calculate charging time when battery capacity is 60 kWh and charging power is 7.2 kW.

EV Technology

charging_time = [1] / [2]

Drag options to blanks, or click blank then click option'

A7.2

B60

C12

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping numerator and denominator.

Using incorrect values for capacity or power.

Charging time = battery capacity (60 kWh) divided by charging power (7.2 kW).

3fill in blank

hard

Fix the error in the formula to correctly calculate charging time.

EV Technology

charging_time = battery_capacity [1] charging_power

Drag options to blanks, or click blank then click option'

A+

B-

C/

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication or addition instead of division.

Confusing units of power and energy.

The correct operation is division to find charging time.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps battery capacities to charging times for powers above 5 kW.

EV Technology

charging_times = {capacity: capacity [1] power for capacity, power in data.items() if power [2] 5}

Drag options to blanks, or click blank then click option'

A/

B>

C<

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication instead of division.

Using wrong comparison operator in filter.

The comprehension divides capacity by power and filters powers greater than 5 kW.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps battery capacities to charging times only for capacities above 40 kWh and charging powers above 6 kW.

EV Technology

charging_times = { [1]: [2] [3] power for [1], power in data.items() if [1] > 40 and power > 6 }

Drag options to blanks, or click blank then click option'

Acapacity

C/

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication instead of division.

Using wrong variable names or missing filter conditions.

The comprehension uses 'capacity' as key and value divided by power as value, filtering capacities > 40 and powers > 6.

Practice

1. What is the basic formula to calculate the charging time of an electric vehicle?

easy

A. Charging time = Battery capacity ÷ Charging power

B. Charging time = Charging power ÷ Battery capacity

C. Charging time = Battery capacity x Charging power

D. Charging time = Battery capacity + Charging power

Solution

1. Step 1: Understand the formula components

   Charging time depends on how much energy the battery holds (capacity) and how fast the charger can deliver power (charging power).

2. Step 2: Apply the correct formula

   Charging time is calculated by dividing battery capacity by charging power, meaning how many hours it takes to fill the battery at that power.

3. Final Answer:

   Charging time = Battery capacity ÷ Charging power -> Option A

4. Quick Check:

   Charging time = Capacity ÷ Power [OK]

Hint: Divide battery capacity by charging power to get time [OK]

Common Mistakes:

• Swapping numerator and denominator
• Multiplying instead of dividing
• Adding capacity and power
• Confusing units of measurement

2. Which of the following correctly represents the units for charging time if battery capacity is in kWh and charging power is in kW?

easy

A. Kilowatt-hours (kWh)

B. Kilowatts (kW)

C. Hours (h)

D. Minutes (min)

Solution

1. Step 1: Analyze units in the formula

   Battery capacity is in kilowatt-hours (kWh), charging power is in kilowatts (kW).

2. Step 2: Calculate resulting units

   Dividing kWh by kW leaves hours (kWh ÷ kW = h), which is the unit for charging time.

3. Final Answer:

   Hours (h) -> Option C

4. Quick Check:

   kWh ÷ kW = hours [OK]

Hint: Divide energy (kWh) by power (kW) to get hours [OK]

Common Mistakes:

• Confusing kW with kWh
• Choosing power units instead of time
• Ignoring unit conversion
• Selecting minutes without conversion

3. An electric vehicle has a battery capacity of 60 kWh and is charged with a 12 kW charger. What is the approximate charging time?

medium

A. 5 hours

B. 0.2 hours

C. 72 hours

D. 720 hours

Solution

1. Step 1: Identify given values

   Battery capacity = 60 kWh, Charging power = 12 kW.

2. Step 2: Calculate charging time

   Charging time = 60 ÷ 12 = 5 hours.

3. Final Answer:

   5 hours -> Option A

4. Quick Check:

   60 ÷ 12 = 5 [OK]

Hint: Divide 60 by 12 to get 5 hours [OK]

Common Mistakes:

• Multiplying instead of dividing
• Confusing units
• Choosing unrealistic large or small values
• Ignoring decimal points

4. A user calculates charging time as Battery capacity x Charging power instead of dividing. If the battery is 40 kWh and charger is 8 kW, what error will this cause?

medium

A. Charging time will be zero

B. Charging time will be overestimated

C. Charging time will be underestimated

D. Charging time will be correct

Solution

1. Step 1: Calculate correct charging time

   Correct time = 40 ÷ 8 = 5 hours.

2. Step 2: Calculate incorrect charging time

   Incorrect time = 40 x 8 = 320 hours, which is much larger than correct time.

3. Final Answer:

   Charging time will be overestimated -> Option B

4. Quick Check:

   Multiplying inflates time, so overestimation [OK]

Hint: Multiplying instead of dividing inflates charging time [OK]

Common Mistakes:

• Using multiplication instead of division
• Ignoring units
• Assuming multiplication reduces time
• Confusing battery capacity and power

5. An EV owner wants to charge a 75 kWh battery using a charger that provides 50 kW for the first hour, then slows to 10 kW for the remaining charge. What is the total approximate charging time?

hard

A. 2.5 hours

B. 5.5 hours

C. 4.5 hours

D. 3.5 hours

Solution

1. Step 1: Calculate energy charged in first hour

   Energy charged = Power x Time = 50 kW x 1 hour = 50 kWh.

2. Step 2: Calculate remaining energy and time

   Remaining energy = 75 - 50 = 25 kWh. Charging power now is 10 kW, so time = 25 ÷ 10 = 2.5 hours.

3. Step 3: Calculate total charging time

   Total time = 1 hour + 2.5 hours = 3.5 hours.

4. Final Answer:

   3.5 hours -> Option D

5. Quick Check:

   1 + (25 ÷ 10) = 3.5 hours [OK]

Hint: Add fast charge hour plus remaining energy ÷ slow power [OK]

Common Mistakes:

• Ignoring change in charging power
• Adding powers instead of times
• Calculating total energy incorrectly
• Forgetting to subtract charged energy