Battery and power system in Drone Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Calculate Remaining Battery Percentage

What is the output of this code that calculates the remaining battery percentage after a flight segment?

Drone Programming

battery_capacity = 5000  # in mAh
used_capacity = 1250
remaining_percentage = (battery_capacity - used_capacity) / battery_capacity * 100
print(f"Remaining battery: {remaining_percentage:.1f}%")

A Remaining battery: 80.0%

B Remaining battery: 25.0%

C Remaining battery: 75.0%

D Remaining battery: 50.0%

💡 Hint

Remember to subtract used capacity from total capacity before calculating percentage.

The remaining battery is calculated by subtracting used capacity (1250 mAh) from total capacity (5000 mAh), then dividing by total capacity and multiplying by 100 to get the percentage.

🧠 Conceptual

intermediate

Battery Voltage and Power Output

If a drone battery outputs 11.1 volts and the drone consumes 20 amps, what is the power output in watts?

A 222 watts

B 31.1 watts

C 2200 watts

D 2.22 watts

💡 Hint

Power (watts) = Voltage (volts) × Current (amps).

Power is calculated by multiplying voltage (11.1 V) by current (20 A), which equals 222 watts.

🔧 Debug

advanced

Identify the Error in Battery Status Update Code

What error does this code raise when updating the battery status?

Drone Programming

battery_status = {'voltage': 11.1, 'current': 20}
# Update voltage
battery_status['voltage'] = 11.5
# Calculate power output
power_output = battery_status['voltage'] * battery_status['current']
print(power_output)

A No error, prints 230.0

B KeyError: 'voltage'

C TypeError: unsupported operand type(s) for *: 'str' and 'int'

D AttributeError: 'dict' object has no attribute 'voltage'

💡 Hint

Check how dictionary keys are accessed in Python.

Dictionaries require bracket notation for key access; dot notation causes AttributeError.

📝 Syntax

advanced

Find the Syntax Error in Battery Check Function

Which option contains the correct syntax for this battery check function?

Drone Programming

def check_battery_level(level):
    if level < 20
        return "Low battery"
    else:
        return "Battery OK"

A

def check_battery_level(level):
    if level < 20
        return "Low battery"
    else
        return "Battery OK"

B

def check_battery_level(level):
    if level < 20:
        return "Low battery"
    else:
        return "Battery OK"

C

def check_battery_level(level):
    if level < 20:
    return "Low battery"
    else:
        return "Battery OK"

D

def check_battery_level(level):
    if level < 20:
        return "Low battery"
    else
        return "Battery OK"

💡 Hint

Remember to put a colon ':' after the if condition.

Python requires a colon after the if statement and proper indentation for the return statements.

🚀 Application

expert

Calculate Flight Time Based on Battery and Power Consumption

Given a drone battery capacity of 6000 mAh and an average current draw of 15 amps at 11.1 volts, what is the approximate flight time in minutes? (Assume 1 Ah = 1000 mAh and ignore efficiency losses.)

A 24 minutes

B 44 minutes

C 40 minutes

D 22 minutes

💡 Hint

Convert mAh to Ah, then divide capacity by current draw to get hours, then convert to minutes.

6000 mAh = 6 Ah. Flight time (hours) = 6 Ah / 15 A = 0.4 hours = 24 minutes. Alternatively, battery energy = 11.1 V × 6 Ah = 66.6 Wh, power = 11.1 V × 15 A = 166.5 W, time = 66.6 / 166.5 = 0.4 hours = 24 minutes.

Practice

1. What is the main purpose of a battery in a drone?

easy

A. To send signals to the controller

B. To control the drone's speed

C. To store energy so the drone can fly

D. To cool down the drone's motors

Solution

1. Step 1: Understand the battery's role

   A battery stores electrical energy that powers the drone's motors and electronics.

2. Step 2: Compare options to battery function

   Only storing energy matches the battery's main purpose; other options describe different parts.

3. Final Answer:

   To store energy so the drone can fly -> Option C

4. Quick Check:

   Battery = Energy storage [OK]

Hint: Battery stores energy for flight power [OK]

Common Mistakes:

• Confusing battery with motor controller
• Thinking battery controls speed
• Mixing battery with communication parts

2. Which of the following is the correct way to check if the battery level is below 20% in drone code?

easy

A. if battery_level == '20%':

B. if battery_level < 20:

C. if battery_level > 20:

D. if battery_level = 20:

Solution

1. Step 1: Identify correct comparison operator

   To check if battery is below 20%, use less than operator: <.

2. Step 2: Check syntax correctness

   if battery_level < 20: uses correct syntax and operator; others use assignment (=), wrong comparison (>), or wrong type ('20%').

3. Final Answer:

   if battery_level < 20: -> Option B

4. Quick Check:

   Use < for less than check [OK]

Hint: Use '<' to check if battery is below threshold [OK]

Common Mistakes:

• Using '=' instead of '==' or '<'
• Comparing to string '20%'
• Using '>' instead of '<'

3. What will be the output of this code snippet?

battery_level = 15
if battery_level < 20:
    print('Warning: Low battery')
else:
    print('Battery level OK')

medium

A. Battery level OK

B. No output

C. SyntaxError

D. Warning: Low battery

Solution

1. Step 1: Check battery_level value

   battery_level is 15, which is less than 20.

2. Step 2: Evaluate the if condition

   Since 15 < 20 is True, the code prints 'Warning: Low battery'.

3. Final Answer:

   Warning: Low battery -> Option D

4. Quick Check:

   15 < 20 triggers warning [OK]

Hint: Compare battery_level to 20 to decide output [OK]

Common Mistakes:

• Confusing output messages
• Thinking 15 is not less than 20
• Expecting syntax error

4. Identify the error in this drone battery check code:

if battery_level = 10:
    print('Battery low')

medium

A. Using '=' instead of '==' for comparison

B. Missing colon ':' after if statement

C. battery_level should be a string

D. print statement syntax is wrong

Solution

1. Step 1: Check the if statement syntax

   The code uses '=' which is assignment, not comparison.

2. Step 2: Correct comparison operator

   To compare, '==' must be used, so 'if battery_level == 10:' is correct.

3. Final Answer:

   Using '=' instead of '==' for comparison -> Option A

4. Quick Check:

   Use '==' to compare values [OK]

Hint: Use '==' to compare, not '=' [OK]

Common Mistakes:

• Using '=' in if condition
• Forgetting colon
• Wrong print syntax

5. You want to write a function that returns 'Safe to fly' if battery level is 30% or more, and 'Charge battery' otherwise. Which code correctly implements this?

hard

A. def check_battery(level):
if level >= 30:
return 'Safe to fly'
else:
return 'Charge battery'

B. def check_battery(level):
if level > 30:
return 'Charge battery'
else:
return 'Safe to fly'

C. def check_battery(level):
if level == 30:
return 'Safe to fly'
else:
return 'Charge battery'

D. def check_battery(level):
if level <= 30:
return 'Safe to fly'
else:
return 'Charge battery'

Solution

1. Step 1: Understand the condition for safe flight

   Safe to fly if battery level is 30% or more means level >= 30.

2. Step 2: Check each option's logic

   def check_battery(level): if level >= 30: return 'Safe to fly' else: return 'Charge battery' correctly returns 'Safe to fly' when level >= 30, else 'Charge battery'. Others reverse or misapply conditions.

3. Final Answer:

   def check_battery(level): if level >= 30: return 'Safe to fly' else: return 'Charge battery' -> Option A

4. Quick Check:

   Use >= 30 for safe flight check [OK]

Hint: Use '>=' to include 30% as safe [OK]

Common Mistakes:

• Using '>' instead of '>='
• Reversing return messages
• Checking only equality