Battery Life Calculator
Estimate runtime, required capacity, or maximum current for battery-powered devices.
Advanced Settings
Enter values to see results
Tips for Accuracy
- • Use actual measured current, not datasheet typical values
- • Account for all power modes (active, sleep, deep sleep)
- • Consider temperature effects on battery capacity
- • Add 20-30% safety margin to your estimates
Battery Chemistry Reference
| Chemistry | Nominal V | Max DoD | Self-Discharge | Notes |
|---|---|---|---|---|
| Li-ion / LiPo | 3.7V | 80-90% | 2-3%/month | Most IoT applications |
| LiFePO4 | 3.2V | 80% | 1-2%/month | Long cycle life |
| Alkaline | 1.5V | 90% | 2-3%/year | Primary (non-rechargeable) |
| NiMH | 1.2V | 90% | 15-20%/month | High self-discharge |
| Lead Acid | 2V/cell | 50% | 3-5%/month | Deep cycle rated |
| CR2032 (Lithium) | 3V | 90% | 1%/year | Coin cell, very low self-discharge |
Understanding Battery Life
Battery runtime depends on capacity, average current draw, and efficiency factors. For devices with multiple power modes, the duty cycle of each mode determines the average current consumption.
Basic Formula
A 2000mAh battery at 100mA gives 20 hours. But real-world factors reduce this.
Duty Cycle Average
If a device uses 50mA for 10% of the time and 10µA for 90%, average = 5.009mA.
Power Optimization Strategies
Use Sleep Modes
Modern MCUs can drop to µA levels in sleep. Wake only when needed using interrupts or timers.
Reduce Transmit Time
Radio transmission is the biggest power consumer. Batch data, use compression, and minimize TX power.
Lower Clock Speed
Run at the minimum clock speed needed. Many MCUs scale power linearly with frequency.
Power Gating
Use MOSFETs to completely disconnect unused peripherals like sensors, LEDs, or communication modules.
Efficient Regulators
Switching regulators are more efficient than linear regulators, especially with large voltage drops.
Measure Real Current
Datasheet values are typical. Use a current meter or power profiler to measure actual consumption.
Example Scenarios
IoT Temperature Sensor
- • Battery: CR2032 (225mAh)
- • Active: 15mA for 100ms every 10min (0.017% duty)
- • Sleep: 2µA (99.98% duty)
- • Average: 2.6µA
- • Runtime: ~8 years theoretical
GPS Tracker
- • Battery: 18650 (2600mAh)
- • GPS Fix: 35mA for 30s every 5min (10% duty)
- • Transmit: 150mA for 2s every 5min (0.67% duty)
- • Sleep: 50µA (89.3% duty)
- • Runtime: ~20 days