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Category Electronics

Power Source

Battery Capacity (mAh)

Efficiency Factor (0.1 - 1.0)Default 0.8 accounts for regulator loss/safety margin.

Components

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About

Power budgeting defines the viability of autonomous electronics. In IoT deployments or remote sensor nodes, underestimating the total current draw leads to premature field failures and costly maintenance. This tool aggregates the current consumption of individual components - microcontrollers, sensors, wireless modules, and indicators - to model the system's total load. It applies a safety derating factor to the battery capacity, accounting for non-ideal discharge curves, temperature inefficiencies, and self-discharge rates. Accurate estimation dictates whether a project requires a larger cell, a solar harvester, or aggressive sleep-mode optimization.

Formulas

The total system current is the sum of all individual component currents. For accurate lifecycle prediction, we apply an efficiency factor to the battery rating.

Total Current Load:

I_total = n∑i=1 I_i

Estimated Runtime:

T = C_batt × ηI_total

Where T is time in hours, C_batt is battery capacity in mAh, and η is the efficiency factor (typically 0.8).

Reference Data

Component Type	Typical Active Current (mA)	Sleep/Standby (mA)	Notes
Arduino Uno (ATmega328P)	45 - 50	0.15	5V logic, regulator dependent
ESP8266 (Wi-Fi)	80 (Tx: 170)	0.02	High spikes during RF transmission
ESP32 (Wi-Fi/BLE)	160 - 260	0.01	Dual-core active
Raspberry Pi 4 (Idle)	600	N/A	Linux OS overhead
OLED Display (0.96")	20	0.05	Varies with pixel brightness
Standard LED (Red)	20	0	Resistor dependent
Ultrasonic Sensor (HC-SR04)	15	2	Burst ranging
GPS Module (NEO-6M)	45 - 50	0.5	Satellite acquisition mode
LoRa Module (SX1278)	120 (Tx)	0.001	Long range, low idle
Temperature Sensor (DHT11)	2.5	0.1	During conversion
Servo Motor (SG90)	100 - 250	10	Load dependent
GSM Module (SIM800L)	250 (Peak 2000)	1	Requires high current capacitor

Frequently Asked Questions

Batteries rarely deliver their full rated capacity due to the Peukert effect, voltage regulators, and thermal losses. We apply a default derating factor (Efficiency) of 0.8 to account for these real-world losses, providing a safer, more conservative estimate for project planning.

For prototyping, estimate the "Average" current. If a device sleeps at 0.1mA for 90% of the time and runs at 100mA for 10%, the weighted average is (0.1 * 0.9) + (100 * 0.1) = 10.09mA. Use this weighted value in the current field for higher accuracy.

No. Linear regulators dissipate excess voltage as heat. If you are stepping down 9V to 5V with a linear regulator, the current drawn from the battery is roughly equal to the load current, but energy is wasted. Switching regulators are more efficient but complex. Adjust the efficiency factor downward (e.g., 0.7) if using inefficient linear regulators.

Lithium Polymer (LiPo) cells should not be discharged below 3.0V - 3.2V per cell to prevent permanent chemical damage. The usable capacity is often 80-90% of the label rating. Set the efficiency factor to 0.8 to respect this safety margin.