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Battery Run Time Calculator

Estimate how long your battery will last under a specific electrical load, accounting for battery chemistry and discharge safety limits.

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Battery Run Time Calculator

Estimate battery life and runtime under load

Volts (V)

Estimated Runtime

Recommended Safe Runtime
0 hours
Keeps battery above target discharge safety limit
Total Energy Capacity
0 Wh
Theoretical Runtime (100% discharge): 0 hours
Equivalent Amps drawn: 0 A
Send output to:
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How to use Battery Run Time Calculator

  1. Enter the Battery Capacity in Amp-hours (Ah) or Milliamp-hours (mAh).
  2. Enter the Battery Voltage (e.g., 12V, 3.7V).
  3. Enter the Load either in Watts (W) or Current in Amps (A).
  4. Select the battery type or specify a custom discharge depth percentage.
  5. View the estimated battery run time in hours, minutes, and days.

What is Battery Run Time Calculator?

Battery capacity is measured in Amp-hours (Ah) or Milliamp-hours (mAh). The theoretical run time is Capacity / Current. However, real-world battery discharge curves, Peukert's law, inverter efficiency, and safety guidelines mean batteries should not be fully discharged to 0% (especially Lead-Acid batteries, which are typically discharged to 50% max; lithium batteries can go up to 80-90%).

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FAQ

Why shouldn't I discharge a battery to 0%?
Discharging a battery fully can severely reduce its lifespan or cause permanent damage. Lead-acid batteries should not exceed 50% depth of discharge, while Lithium-ion batteries can safely discharge up to 80-90%.
How does voltage affect battery run time?
Total energy stored is Capacity (Ah) × Voltage (V) = Watt-hours (Wh). A 12V 100Ah battery stores 1200Wh, twice as much energy as a 6V 100Ah battery (600Wh).

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