Battery Life Calculator Runtime Estimator

Calculate battery runtime based on capacity, load current, and discharge rate

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📖 Battery Life Calculator

This battery life calculator helps you estimate the runtime of a battery based on its capacity, load current, and discharge characteristics. It supports various battery chemistries and provides runtime in hours, minutes, and days.

📐 Battery Life Formula

Capacity (mAh): C = Battery Capacity
Load Current (mA): I = Load Current
Runtime (hours): t = (C × 0.8) / I
Capacity (Wh): Wh = Ah × V
Power (W): P = I × V

📊 Typical Battery Capacities

DeviceCapacityVoltageTypical Runtime
Smartphone3000-5000 mAh3.7V6-12 hours
Laptop40-90 Wh11.1-14.8V4-8 hours
Power Bank10000-20000 mAh3.7VVaries
UPS Battery7-12 Ah12V10-30 min
Car Battery40-100 Ah12VHours
AA Alkaline2000-3000 mAh1.5VVaries

❓ Frequently Asked Questions

How do I calculate battery life? ▼
Battery life = (Battery Capacity × Discharge Depth) / Load Current. For example, a 2000mAh battery with 80% discharge depth and 500mA load gives 2000 × 0.8 / 500 = 3.2 hours.
What is discharge depth? ▼
Discharge depth is the percentage of capacity you use before recharging. For lithium-ion, 80% is recommended to extend battery life. Deep discharge (100%) reduces cycle life.
What is the difference between mAh and Wh? ▼
mAh (milliamp-hours) measures charge capacity at a specific voltage. Wh (watt-hours) measures energy capacity independent of voltage: Wh = Ah × V. Wh is more accurate for comparing batteries at different voltages.
How do I extend battery life? ▼
Keep lithium-ion batteries between 20-80% charge, avoid high temperatures, use appropriate chargers, and reduce high-current loads.