Battery Runtime Calculator
Calculate battery runtime, capacity requirements, and charging time for various load conditions
About this calculator
The Battery Runtime Calculator helps you determine how long your battery will power a device, what battery capacity you need for specific runtime requirements, and how long it takes to charge your battery. This tool is essential for engineers, technicians, and anyone working with battery-powered devices who needs to optimize power management, plan backup power systems, or ensure adequate battery life for critical applications.
How to use
Enter your battery capacity in amp-hours (Ah) or watt-hours (Wh), then input the power consumption of your load in watts or amps. The calculator will instantly show you the expected runtime. You can also reverse the calculation by entering desired runtime to find required battery capacity.
Frequently asked questions
What factors affect actual battery runtime?
Temperature, battery age, discharge rate, and battery chemistry all impact runtime. Cold temperatures and high discharge rates typically reduce actual runtime below calculated values.
How accurate are battery runtime calculations?
Calculations provide good estimates but actual runtime may vary by 10-20% due to battery efficiency curves, environmental conditions, and load variations during operation.
What's the difference between Ah and Wh ratings?
Amp-hours (Ah) measure current capacity over time, while watt-hours (Wh) measure energy capacity. Wh = Ah × voltage and is more accurate for power calculations.