Battery Life Calculator

Battery life estimation uses the fundamental relationship between stored energy (capacity) and energy consumption rate (current draw). Battery capacity is measured in milliamp-hours (mAh) or amp-hours (Ah), representing the amount of current a battery can supply for one hour before depleting. The basic formula, Life = Capacity / Consumption, provides a theoretical maximum. Real-world battery life is typically 70-80% of this theoretical value due to several factors: battery voltage sag under load, temperature effects, self-discharge, and the inability to fully discharge without damaging the battery. Battery chemistry affects performance significantly. Lithium-ion batteries maintain relatively stable voltage throughout discharge but should not be drained below 20% for longevity. Lead-acid batteries can deliver high currents but lose capacity when discharged rapidly (Peukert effect). Alkaline batteries experience significant voltage drop during discharge. For devices with variable power consumption (like smartphones), the average consumption must account for different usage scenarios: screen-on time, wireless connectivity, GPS usage, and processor load. Manufacturers typically test battery life under specific standardized conditions that may not match your actual usage patterns. When designing electronics projects, it is good practice to add a 20-30% safety margin to your battery life calculations. This accounts for real-world inefficiencies and ensures the device operates reliably throughout its intended use period.