3.2: Battery

Step 1

Getting Started

Make sure that your drone is connected with Blockly before starting the lesson! If you are unsure of how to connect, go back to lesson 1.1 to review!

Step 2

Goals and Steps to Success

Goals:

By the end of this lesson, I will be able to:

Explain the importance of measuring battery level
Describe how the battery level is reported by your CoDrone EDU
Use the get_battery_percentage function to measure the drone’s battery level
Store and print the drone’s battery level
Use battery level to restrict flight movements
Use the LED to indicate battery level

Steps to Success:

Battery Indicator
Printing the Battery Level
Before and After
Limiting Takeoff
Adding the LED
Add Conditionals to Your LED Program
Adding elif Statements
Adding an else Statement
Final LED Code
Challenge 1: Battery Calculator
Challenge 2: Battery Charge Reporter

Step 3

Battery Indicator

Most electronic devices use batteries. Your laptop, cellphone, radio, tv remote, video game consoles, and even your car all have batteries. How do you know when your device needs to be charged or replaced?

Typically, a red battery icon or LED will let you know that a battery is running low. You may have noticed your CoDrone EDU flashing red and making a sound when the battery is running low. In this lesson, you will learn how to request the battery level and change the LED yourself!

Step 4

Printing the battery level

Requesting the battery level may not seem like a sensor reading, but you are actually measuring the battery’s voltage. Open the senior Sensors category to find the battery block near the middle of the list.

Step 5

Before and after

You probably won’t notice a big difference in the percentage yet, so add some flying! Print the battery percentage before and after hovering for 10 seconds.

What was the difference? You might notice that it drops a lot! This is because you are actually reading the voltage value at that moment in time. After your program ends, you will notice that the battery level comes back up after a few seconds.

Step 6

Limiting takeoff

In this exercise, you will write a program that will either takeoff or do nothing depending on the battery level.

First, include the program that you wrote in the last step which will print out your drone’s battery level. Next, write a conditional so that if the battery level is greater than 50, it will take off, hover for 2 seconds, and land. Else, it will print “Not enough power!” and stay grounded.

Try changing the battery level in the conditional to a different number. What happens?

Step 7

Adding the LED

The LED on your CoDrone EDU already acts as a battery indicator — when your battery is low, it flashes red. In this program, you will be adding more colors to indicate different battery percentages.

First, start with the code from the last step that will print the battery percentage.

Step 8

Add conditionals to your LED program

You are going to use conditionals to check your battery’s percentage. Depending on your battery level, your CoDrone EDU’s LED will turn a certain color. You can change them to whatever you want, but we recommend you make them easy to tell apart so you know when you need to charge your battery. This is what we’re going to use for this lesson:

100-76: solid green LED
75-51: solid yellow LED
50-26: solid red LED
25-0: will not fly

Next, write an if statement that will change your CoDrone EDU’s LED to green when the battery level is above 75%. Include a delay so flight movements after the LED change aren’t skipped, and then add a takeoff command.

battery-addconditional-senior-cde-blockly

Step 9

Adding elif statements

Do the same for 51-75% battery and then 26-50% battery, but with a few changes:

Instead of if statements, use else if statements.
Instead of the battery being greater than 75%, it should be greater than 50% and then 25%.

Step 10

Adding an else statement

Add an else statement to indicate that if none of the above statements are true and your battery is less than 25%, your drone does not have enough power to fly!

All of the conditionals above 25% have a takeoff command included, so include any flight commands you would like in your program after the else statement. Don’t forget to land and close your drone!

Step 11

Final LED code

Your final code should look like this:

Step 12

Challenge 1: Battery Calculator

For this challenge, we want to predict whether or not our drone will be able to fly the flight path we have programmed for it. To do this, repeat the step where we checked the difference in battery power after a takeoff, wait, and land. Figure out how much battery is lost per 5 seconds of flight time:

Takeoff, hover 5 seconds, land -> take before and after battery measurements
Takeoff, hover 10 seconds, land -> take before and after battery measurements
Take the difference of the battery usage between steps 1 and 2. This is your battery drain per 5 seconds of stationary flight.

Now, write a flight plan that has at least 5 movements and at least 30 seconds of flight time. Store the beginning and ending battery percentage. Also store the beginning and ending flight time. Print both of these values at the end of the flight, after landing.

When you run the program, time it and make a prediction as to how much battery life you will lose. Check your drone’s output versus your prediction. How close was your prediction? What could be causing any differences?

Step 13

Lesson Complete

In this lesson, you learned about the CoDrone EDU’s battery sensor, including how to access and print the data from the sensor! You can use this battery sensor data for a variety of things, such as limiting takeoff or forcing the CoDrone EDU to land depending on the battery level.

This lesson works with:

Grade level:

Approx. time required:

CSTA

CCSS