| name | power-budget-calculator |
| description | Calculates total power consumption and battery life for Arduino/ESP32/RP2040 projects. Use when user asks about battery life, power requirements, current draw, or needs to estimate runtime. Includes sleep mode analysis, power optimization tips, and battery sizing recommendations. Run scripts/calculate_power.py for accurate calculations. |
Power Budget Calculator
Estimates power consumption and battery life for embedded projects.
Resources
- scripts/calculate_power.py - Python calculator with component database, duty cycle support, battery life estimation
- references/component-database.md - Comprehensive current draw reference from datasheets
- assets/example-project.json - Sample project configuration
Quick Start
Run the calculator interactively:
uv run --no-project scripts/calculate_power.py --interactive
Or calculate for a single component:
uv run --no-project scripts/calculate_power.py --component ESP32 --mode deep_sleep --duty 95
Load a project configuration:
uv run --no-project scripts/calculate_power.py --json assets/example-project.json --output report.md
List all components in database:
uv run --no-project scripts/calculate_power.py --list
When to Use
- "How long will my battery last?"
- "What size battery do I need?"
- "How much current does my project draw?"
- Planning battery-powered projects
- Optimizing for low power
Workflow
Step 1: Gather Component List
Ask user for:
- Microcontroller (model and operating mode)
- All sensors and modules
- Displays
- Actuators (motors, LEDs, relays)
- Communication (WiFi, Bluetooth, LoRa)
- Operating profile (always on vs. duty cycle)
Step 2: Calculate Power Budget
Run scripts/calculate_power.py --interactive for guided calculation, or use this template:
# Power Budget: [Project Name]
## Operating Conditions
- Supply Voltage: [V]
- Operating Modes: [Active/Sleep cycles]
- Duty Cycle: [X% active, Y% sleep]
## Component Current Draw
### Always-On Components
| Component | Voltage | Current | Power | Notes |
|-----------|---------|---------|-------|-------|
| [name] | [V] | [mA] | [mW] | [conditions] |
| ... | ... | ... | ... | ... |
| **Subtotal** | - | **[mA]** | **[mW]** | - |
### Active Mode Only
| Component | Voltage | Current | Power | Duty % |
|-----------|---------|---------|-------|--------|
| [name] | [V] | [mA] | [mW] | [%] |
| ... | ... | ... | ... | ... |
| **Subtotal** | - | **[mA]** | **[mW]** | - |
### Peak Current Events
| Event | Current | Duration | Frequency |
|-------|---------|----------|-----------|
| [WiFi TX] | [mA] | [ms] | [per hour] |
| ... | ... | ... | ... |
## Power Calculations
### Average Current
I_avg = (I_active × t_active + I_sleep × t_sleep) / t_total
I_avg = ([X]mA × [Y]s + [Z]mA × [W]s) / [T]s
I_avg = [result] mA
### Battery Life Estimate
Capacity: [X] mAh
Efficiency factor: 0.8 (80% usable)
Effective capacity: [X × 0.8] mAh
Runtime = Effective capacity / I_avg
Runtime = [X] mAh / [Y] mA
Runtime = [Z] hours ([days] days)
## Recommendations
- [Power optimization suggestions]
- [Battery type recommendation]
- [Sleep mode configuration]
Current Draw Database
Microcontrollers
Arduino (ATmega328P @ 5V)
| Mode | Current | Notes |
|---|
| Active (16MHz) | 15-20mA | No peripherals |
| Idle | 6mA | CPU stopped, peripherals on |
| Power-down | 0.1µA | Only WDT/external interrupt |
| With USB-Serial | +50mA | CH340/FTDI chip always on |
ESP32 (WROOM-32)
| Mode | Current | Notes |
|---|
| Active (WiFi TX) | 160-260mA | Peak during transmission |
| Active (WiFi RX) | 95-100mA | Listening |
| Active (no WiFi) | 20-68mA | CPU only |
| Modem-sleep | 20mA | WiFi off, CPU on |
| Light-sleep | 0.8mA | CPU paused |
| Deep-sleep | 10µA | RTC only |
| Hibernation | 5µA | RTC off |
ESP32-C3
| Mode | Current | Notes |
|---|
| Active (WiFi TX) | 320mA peak | Brief spikes |
| Active (BLE) | 50-100mA | During advertising |
| Active (no radio) | 25-35mA | CPU at 160MHz |
| Light-sleep | 130µA | Auto wake |
| Deep-sleep | 5µA | RTC on |
RP2040 (Pico)
| Mode | Current | Notes |
|---|
| Active (both cores) | 25-50mA | Depends on clock |
| Single core | 15-25mA | One core dormant |
| Dormant | 0.18mA | Wake on GPIO/RTC |
| Sleep | 1.3mA | |
RP2040 (Pico W)
| Mode | Current | Notes |
|---|
| WiFi active | 50-150mA | During TX |
| WiFi idle | 30-40mA | Connected, listening |
| WiFi off | 25-50mA | Radio disabled |
Sensors
| Sensor | Active | Sleep | Notes |
|---|
| DHT22 | 1.5mA | 50µA | During read |
| BME280 | 0.35mA | 0.1µA | Forced mode |
| BMP280 | 0.27mA | 0.1µA | |
| MPU6050 | 3.8mA | 5µA | All axes |
| DS18B20 | 1.5mA | 1µA | During conversion |
| HC-SR04 | 15mA | 2mA | No true sleep |
| VL53L0X | 19mA | 5µA | During ranging |
| MAX30102 | 600µA | 0.7µA | Low power mode |
| BH1750 | 120µA | 1µA | Power down mode |
| GPS (NEO-6M) | 45mA | 11mA | Backup mode |
Displays
| Display | Active | Off/Sleep | Notes |
|---|
| 16x2 LCD (backlight) | 80-120mA | 1mA | Backlight dominates |
| 16x2 LCD (no backlight) | 1-2mA | 1mA | |
| SSD1306 OLED 128x64 | 8-20mA | 10µA | Depends on content |
| SSD1306 OLED 128x32 | 5-15mA | 10µA | |
| ST7735 TFT | 20-40mA | 20mA | Backlight always on |
| ILI9341 TFT | 50-80mA | 50mA | |
| E-Paper 2.9" | 8mA | 0µA | Only during refresh |
Communication Modules
| Module | TX Peak | RX/Idle | Sleep | Notes |
|---|
| ESP8266 (module) | 170mA | 70mA | 20µA | Deep sleep |
| NRF24L01 | 11.3mA | 13.5mA | 0.9µA | |
| HC-05 Bluetooth | 40mA | 8mA | 2mA | |
| RFM95 LoRa | 120mA | 10mA | 0.2µA | |
| SIM800L GSM | 2A peak | 15mA | 1mA | Needs big cap! |
Actuators
| Component | Current | Notes |
|---|
| LED (typical) | 10-20mA | Through resistor |
| RGB LED (each color) | 20mA | Per channel |
| WS2812B NeoPixel | 60mA max | Full white |
| SG90 Servo (idle) | 10mA | No load |
| SG90 Servo (moving) | 200-500mA | Under load |
| MG996R Servo | 500-900mA | Under load |
| Small DC motor | 100-500mA | Varies with load |
| 5V Relay module | 70-100mA | Coil energized |
| Buzzer (passive) | 30mA | |
Sleep Mode Configurations
ESP32 Deep Sleep Template
#include <esp_sleep.h>
#define uS_TO_S_FACTOR 1000000ULL
#define TIME_TO_SLEEP 60
void setup() {
esp_sleep_enable_timer_wakeup(TIME_TO_SLEEP * uS_TO_S_FACTOR);
esp_deep_sleep_start();
}
void loop() {
}
Arduino Power-Down Template
#include <avr/sleep.h>
#include <avr/wdt.h>
void enterSleep() {
set_sleep_mode(SLEEP_MODE_PWR_DOWN);
sleep_enable();
sleep_mode();
sleep_disable();
}
ISR(WDT_vect) {
}
Power Optimization Checklist
Hardware
Software
Design Patterns
Power Gating:
VCC
│
[P-MOSFET] ← GPIO (LOW = ON)
│
[Sensor/Module]
│
GND
Duty Cycling Formula:
I_average = (I_active × T_active + I_sleep × T_sleep) / T_total
Example: Sensor reads every 5 minutes
- Active: 50mA for 2 seconds
- Sleep: 10µA for 298 seconds
I_avg = (50mA × 2s + 0.01mA × 298s) / 300s
I_avg = (100 + 2.98) / 300
I_avg = 0.34mA
With 2000mAh battery:
Runtime = 2000mAh × 0.8 / 0.34mA = 4706 hours = 196 days
Battery Reference
Common Battery Types
| Type | Voltage | Typical Capacity | Notes |
|---|
| CR2032 | 3V | 220mAh | Very low current only |
| 2x AA Alkaline | 3V | 2500mAh | Good for low power |
| 3x AA Alkaline | 4.5V | 2500mAh | Direct to 5V systems |
| 4x AA Alkaline | 6V | 2500mAh | With LDO to 5V |
| 18650 Li-ion | 3.7V | 2000-3500mAh | Rechargeable, popular |
| LiPo 1S | 3.7V | Various | Flat, light |
| 9V Alkaline | 9V | 500mAh | Poor energy density |
Voltage Over Discharge
18650/LiPo Discharge Curve:
Capacity% Voltage
─────────────────────
100% 4.2V
80% 3.9V
50% 3.7V
20% 3.5V
0% 3.0V (cut-off!)
Never discharge below 3.0V - damages cell!
Alkaline AA Discharge:
Capacity% Voltage (per cell)
─────────────────────────────
100% 1.5V
50% 1.2V
0% 0.9V
Many devices stop working below 1.1V/cell
Quick Calculator
Enter your values:
Always-on current: ______ mA
Active current: ______ mA
Active time: ______ seconds
Sleep current: ______ mA
Sleep time: ______ seconds
Battery capacity: ______ mAh
Average current = (Active_mA × Active_s + Sleep_mA × Sleep_s) / Total_s
= (_____ × _____ + _____ × _____) / _____
= _____ mA
Runtime = Capacity × 0.8 / Average_current
= _____ × 0.8 / _____
= _____ hours
= _____ days
