🔋 Battery Life Calculator

Runtime estimation for Li-ion, LiFePO4, LiPo & alkaline batteries

Battery Presets

🔋 18650
3.7V / 2000mAh

🔋 21700
3.7V / 3500mAh

🟢 LiFePO4
3.2V / 3200mAh

⚡ LiPo
3.7V / 1200mAh

🔌 AA Alkaline
1.5V / 2500mAh

🔲 9V Block
9V / 550mAh

Battery Capacity (mAh)

Nominal Voltage (V)

Load Current (mA)

Efficiency (%)
Typical: 85–95%

Battery Chemistry (Peukert Factor)

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0%50%100% capacity

Usable Energy

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Load Power

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C-Rate

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Runtime (w/ Peukert)

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Runtime = (Capacity × Efficiency) / Load Current

Peukert: t = (C / Iⁿ) where n = Peukert exponent

Energy (Wh) = Capacity (Ah) × Voltage

C-Rate = Load Current / Capacity

Actual runtime may vary due to temperature, age, and discharge curve shape. Li-ion retains ~80% capacity after ~500 cycles.