Battery Capacity Calculator

Calculate battery capacity, runtime, and energy

Enter battery specifications to calculate capacity, runtime, and energy consumption

Common Battery Examples

Click on an example to load the values

Smartphone Battery

Smartphone

Typical smartphone battery specifications

Voltage: 3.7 V

Current: 0.5 A

Capacity: 3 Ah

Power: 1.85 W

Runtime: 5.4 h

Efficiency: 90 %

Laptop Battery

Laptop

Standard laptop battery configuration

Voltage: 11.1 V

Current: 2 A

Capacity: 4.4 Ah

Power: 22.2 W

Runtime: 1.87 h

Efficiency: 85 %

Power Bank

Power Bank

Portable power bank specifications

Voltage: 3.7 V

Current: 1 A

Capacity: 10 Ah

Power: 3.7 W

Runtime: 8 h

Efficiency: 80 %

EV Battery Pack

EV Battery Pack

Electric vehicle battery pack example

Voltage: 400 V

Current: 100 A

Capacity: 75 Ah

Power: 40000 W

Runtime: 0.675 h

Efficiency: 95 %

Other Titles
Understanding Battery Capacity Calculator: A Comprehensive Guide
Learn how to calculate battery capacity, energy, and runtime for various applications

What is Battery Capacity?

  • Definition and Units
  • Types of Battery Capacity
  • Importance in Electronics
Battery capacity is a measure of how much electrical charge a battery can store and deliver. It's typically measured in ampere-hours (Ah) or milliampere-hours (mAh) for smaller batteries. The capacity determines how long a battery can power a device before needing to be recharged.
Key Capacity Metrics
There are several important metrics when discussing battery capacity: nominal capacity (theoretical maximum), actual capacity (what you get in practice), and energy capacity (measured in watt-hours). Each serves different purposes in battery analysis and selection.
Energy capacity, measured in watt-hours (Wh), is often more useful than charge capacity because it accounts for both voltage and current. This gives a more accurate picture of how much work a battery can perform.

Capacity Examples

  • A 3000mAh battery at 3.7V has an energy capacity of 11.1Wh
  • A 100Ah car battery at 12V provides 1200Wh of energy

Step-by-Step Guide to Using the Battery Capacity Calculator

  • Input Requirements
  • Calculation Process
  • Interpreting Results
To use the battery capacity calculator effectively, you need to understand what information to provide and how to interpret the results. The calculator can work with various combinations of inputs to provide comprehensive battery analysis.
Required vs Optional Inputs
At minimum, you need voltage and either current or capacity to perform basic calculations. Additional inputs like power, runtime, and efficiency allow for more detailed analysis and optimization of battery performance.
The calculator automatically handles unit conversions and provides results in multiple formats for easy comparison and understanding.

Usage Examples

  • Enter 3.7V and 3000mAh to calculate energy capacity
  • Add 2A current to determine runtime under that load

Real-World Applications of Battery Capacity Calculation

  • Consumer Electronics
  • Electric Vehicles
  • Renewable Energy Systems
Battery capacity calculations are essential in numerous real-world applications, from small consumer electronics to large-scale energy storage systems. Understanding these calculations helps in selecting the right battery for specific applications.
Consumer Electronics
Smartphones, laptops, tablets, and other portable devices rely heavily on accurate battery capacity calculations for optimal performance and user experience. Manufacturers use these calculations to design batteries that provide adequate runtime while maintaining reasonable size and weight.
Power banks and portable chargers also benefit from capacity calculations to ensure they can provide sufficient backup power for various devices.

Application Examples

  • Calculating smartphone battery life based on usage patterns
  • Determining power bank capacity needed for travel

Common Misconceptions and Correct Methods

  • Capacity vs Energy Confusion
  • Runtime Calculation Errors
  • Efficiency Factors
Many people confuse battery capacity (Ah) with energy capacity (Wh), leading to incorrect calculations and poor battery selection. Understanding the difference is crucial for accurate battery analysis.
Capacity vs Energy
Capacity in ampere-hours tells you how much charge a battery can store, while energy in watt-hours tells you how much work it can perform. For accurate runtime calculations, energy capacity is often more useful.
Another common mistake is ignoring efficiency factors. Real-world batteries don't operate at 100% efficiency, so calculations must account for losses in charging, discharging, and internal resistance.

Common Mistakes

  • A 3000mAh battery doesn't always provide 3000mAh of usable capacity
  • Energy capacity (Wh) is more reliable for runtime predictions

Mathematical Derivation and Examples

  • Basic Formulas
  • Advanced Calculations
  • Practical Examples
The fundamental relationship between battery parameters is governed by Ohm's Law and power equations. Understanding these relationships allows for accurate battery capacity calculations and optimization.
Core Formulas
Energy (Wh) = Voltage (V) × Capacity (Ah), Power (W) = Voltage (V) × Current (A), Runtime (h) = Capacity (Ah) ÷ Current (A). These formulas form the foundation of battery capacity calculations.
For more accurate calculations, efficiency factors must be included: Actual Runtime = (Capacity × Efficiency) ÷ Current. This accounts for real-world losses and provides more realistic estimates.

Calculation Examples

  • Energy = 3.7V × 3.0Ah = 11.1Wh
  • Runtime = (3.0Ah × 0.9) ÷ 0.5A = 5.4 hours