Battery Capacity Calculator
Estimate battery amp-hour and watt-hour capacity from voltage, current, and runtime for electronics and backup power.
What is a Battery Capacity Calculator?
A battery capacity calculator estimates the total energy storage capacity of a battery based on its voltage, current rating, and discharge time. It helps you determine the ampere-hour (Ah) or watt-hour (Wh) rating of batteries for electronics, vehicles, solar systems, and backup power applications.
How to Use the Battery Capacity Calculator
Enter the battery voltage and either the ampere-hour rating or the watt-hour rating to convert between them. The calculator also estimates runtime based on the load current. Use this tool to size batteries for your specific application or to compare different battery options.
Frequently Asked Questions
What is the difference between amp-hours and watt-hours?
Amp-hours (Ah) measure the charge capacity of a battery, while watt-hours (Wh) measure the energy capacity. The relationship is Wh = Ah x V, where V is the battery voltage. Watt-hours give a more complete picture of energy storage since they account for voltage.
How do I calculate battery runtime?
Runtime = Battery Capacity (Ah) / Load Current (A). For example, a 100Ah battery powering a 5A load would run for 20 hours. In practice, actual runtime is lower due to efficiency losses and battery discharge characteristics.
What is the C-rate of a battery?
The C-rate describes how fast a battery is charged or discharged relative to its capacity. A 1C rate means the battery delivers its full capacity in 1 hour. A 2C rate delivers the full capacity in 30 minutes. Higher C-rates reduce usable capacity due to internal resistance.
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