Battery Run Time Estimator
Estimate how long a battery will power a given load. Enter battery capacity (mAh or Wh) and device current draw to see hours of runtime.
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Applications
Essential for estimating battery life in portable electronics, drones, electric vehicles, solar battery banks, RC hobbies, camping gear, and any battery-powered device where runtime matters for planning and safety.
The Formula
Runtime (hours) = (Battery Capacity in Wh) ÷ (Load Power in W) × Efficiency. For mAh mode: first convert mAh to Wh using Wh = (mAh × V) ÷ 1000. Efficiency accounts for real-world losses from converters, regulators, heat, and battery chemistry — typically 80–90% for lithium-ion systems.
Fun Fact: A typical AA alkaline battery holds about 2,500 mAh at 1.5V — roughly 3.75 Wh of energy. That is enough to run a 3W LED for just over an hour, or keep a wall clock ticking for nearly a year.
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