Source: https://mokxi.com/teachers/plans/low-power-products Updated: 2026-11-11 Lesson plan # Low power products lesson plan Make a battery last years: where an Uno’s current goes, sleep modes and wake sources, a power budget on a bare chip, measuring with a meter and an INA219, battery life checked against a draining cell, and a coin cell node. 4 chapters, 7 lessons, about 6 hours, on the Arduino Uno R3. Every lesson runs in the browser, with nothing to install. Start a class from this course The unit ## Objectives and materials ### By the end, students can - A meter in series, and what an Uno draws asleep and awake. - Microamps, a power budget, and the tools that measure it. - Predict a battery’s life, then watch it drain. - A coin cell sensor node that sleeps for years. ### Materials for the whole unit - Arduino Uno R3 - ATmega328P, 16 MHz crystal - ATmega328P, 8 MHz internal clock - Battery: AA, coin cell, LiPo - Current monitor, INA219 - Full-size breadboard - Half breadboard - LED - Multimeter - Potentiometer - Pushbutton - Resistor Every part is already on the simulator’s bench, so there is nothing to buy or hand out. The counts are the most any one lesson uses, if you build it on real breadboards too. Chapter 1. About 2 h 35 min ## Where the current goes A meter in series, and what an Uno draws asleep and awake. Lesson | Time | What students do Where the current goes An Uno on a 9 V battery with a meter in series on VIN: 44.9 mA running, what the board takes and what the chip takes, what an LED costs, and what delay() saves. | 45 min - Run it: a meter in series - Most of it is not the chip - The LED - Stop spinning - The honest truth about an Uno Sleep modes Running, idle and power-down on the same Uno, read on the meter: what each sleep mode switches off, what wakes it, and why millis() stands still in power-down. | 55 min - Run it: three ways to spend two seconds - Running - Idle - Power-down - Time stands still - The modes in between Wake sources Sleep in power-down until something worth waking for: the watchdog on a timer, or a pin change from a button. Which interrupt woke it, and the race you must close before sleeping. | 55 min - Run it: asleep until needed - Asleep, the meter - The watchdog wakes it - A pin change wakes it - Wake more often - Close the race ### Materials - Arduino Uno R3 - Battery: AA, coin cell, LiPo - Half breadboard - Multimeter - Pushbutton ### Check for understanding Each student finishes "Wake sources" on their own, without opening the hints. The simulator checks 6 of its 6 steps as they go. Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Close the race". Chapter 2. About 1 h 40 min ## The bare chip Microamps, a power budget, and the tools that measure it. Lesson | Time | What students do A power budget A bare ATmega328P on three AA cells wakes once a second, works and sleeps: microamps asleep on the meter, why the meter cannot catch a short wake, and a budget that turns a duty cycle into days. | 55 min - Run it: no board at all - Microamps - What the meter misses - Measure the wake - Work less - Your budget table Measuring with the INA219 An INA219 in the node’s supply, read by an Uno over I2C: it catches the 10.4 mA wake the meter averages away, cannot see 7 uA of sleep, and the meter in series covers that. | 45 min - Run it: a power analyzer you built - It catches the wake - Peak, floor, average - What the INA219 cannot see - Pick the tool ### Materials - Arduino Uno R3 - ATmega328P, 16 MHz crystal - Battery: AA, coin cell, LiPo - Current monitor, INA219 - Full-size breadboard - LED - Multimeter - Resistor ### Check for understanding Each student finishes "Measuring with the INA219" on their own, without opening the hints. The simulator checks 5 of its 5 steps as they go. Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Pick the tool". Chapter 3. About 45 min ## Batteries Predict a battery’s life, then watch it drain. Lesson | Time | What students do Battery life math Predict how long a battery lasts, then watch it drain: an Uno counts the charge through an INA219, checks the prediction, and finds out why the battery outlives the simple sum. | 45 min - Run it: a tiny battery - The prediction - Watch it sag - Half gone, late - Real batteries ### Materials - Arduino Uno R3 - ATmega328P, 16 MHz crystal - Battery: AA, coin cell, LiPo - Current monitor, INA219 - Full-size breadboard - LED - Resistor ### Check for understanding Each student finishes "Battery life math" on their own, without opening the hints. The simulator checks 5 of its 5 steps as they go. Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Real batteries". Chapter 4. About 55 min ## Boss project A coin cell sensor node that sleeps for years. Lesson | Time | What students do Boss: a coin cell sensor node An 8 MHz ATmega328P on one CR2032 wakes on the watchdog, powers its sensor from a pin, reads it, reports and sleeps, and works out from its own wake time how many days the cell will last. | 55 min - Run it: a node on a coin - The sensor costs more than the chip - Its own budget - Raise the alarm - Sleep longer - Ship it ### Materials - ATmega328P, 8 MHz internal clock - Battery: AA, coin cell, LiPo - Full-size breadboard - LED - Multimeter - Potentiometer - Resistor ### Check for understanding Each student finishes "Boss: a coin cell sensor node" on their own, without opening the hints. The simulator checks 6 of its 6 steps as they go. Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Ship it". Your class ## Teach this unit as a class Start a class from this course and its 7 lessons are assigned in one go, in order. Students join with a six-character code or printed login cards, and each one’s work comes back to you. The class tools are free for 30 days for one class of up to 20 students, with no card. The lessons themselves are free either way. Start a class from this course See the demo class More units ## Other lesson plans Electronics basics 20 lessons, about 10 h. Embedded on the Arduino Uno 16 lessons, about 12 h. Embedded on the ESP32-C3 13 lessons, about 11 h. Embedded on the Raspberry Pi Pico 7 lessons, about 6 h. Build your own fight stick 5 lessons, about 4 h. Embedded on the STM32F411 6 lessons, about 6 h. C++ on a board 13 lessons, about 10 h. Digital logic and memory 4 lessons, about 4 h. Interactive devices on the Uno 9 lessons, about 8 h. From gates to a computer 23 lessons, about 16 h. Build a claw machine 8 lessons, about 6 h. Every unit All the courses as ready-made units, on the teachers page.