Tool description

The Battery Life Calculator helps you estimate how long a battery will last based on its capacity, the current draw of your device, voltage, and efficiency factors. This tool is essential for electronics projects, portable device design, power consumption analysis, and understanding battery runtime in various applications.

Features

  • Multiple Capacity Units: Support for mAh (milliampere-hours), Ah (ampere-hours), and Wh (watt-hours)
  • Multiple Current Units: Calculate with mA (milliamperes), A (amperes), or W (watts)
  • Voltage Configuration: Adjust voltage for accurate power calculations (default: 3.7V for Li-ion batteries)

What is Battery Capacity

Battery capacity is the amount of electrical energy a battery can store and deliver. It's measured in different units:

  • mAh (milliampere-hours): Common for small batteries (smartphones, power banks). 1000mAh = 1Ah
  • Ah (ampere-hours): Used for larger batteries (car batteries, solar systems)
  • Wh (watt-hours): Energy capacity that accounts for voltage. More accurate for comparing different battery types

Calculation Details

The calculator uses the following approach:

  1. Convert to Wh: All capacities are converted to watt-hours using the formula: Wh = (Capacity × Voltage)
  2. Convert to Watts: All current draws are converted to watts: W = (Current × Voltage)
  3. Apply Efficiency: Real-world batteries don't deliver 100% of their rated capacity. The efficiency factor (typically 80-95%) accounts for this
  4. Calculate Runtime: Battery Life (hours) = (Effective Capacity in Wh) / (Power Draw in W)

Example Calculation:

  • Battery: 2000mAh at 3.7V = 7.4Wh
  • Device draws: 100mA at 3.7V = 0.37W
  • Efficiency: 90%
  • Runtime: (7.4 × 0.9) / 0.37 = 18 hours

Supported Units

Capacity Units:

  • mAh (milliampere-hours)
  • Ah (ampere-hours)
  • Wh (watt-hours)

Current Units:

  • mA (milliamperes)
  • A (amperes)
  • W (watts)

Voltage:

  • Common voltages: 1.5V (alkaline), 3.7V (Li-ion), 12V (lead-acid), 5V (USB)

Efficiency:

  • Percentage from 1% to 100%
  • Typical values: 80-95% for most rechargeable batteries