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Battery Run Time Calculator

Estimate battery run time for portable devices by accounting for usable capacity, converter efficiency, and depth of discharge for accurate battery life planning.

Boost/buck converter efficiency. High-quality converters: 85�95%. Linear regulators: 60�80%.
Li-ion: 80% for longevity, 100% for max runtime. LiFePO4: 90�100%.

Results

Usable Capacity6,800 mAh
Estimated Run Time13.60 hours

📖What is it?

Battery run time depends on usable capacity (rated capacity � depth of discharge) reduced by converter inefficiency. Usable mAh = capacity � DoD% � efficiency%. Run time = usable mAh / load current. Manufacturer mAh ratings are at a slow 0.1C discharge; actual capacity decreases at higher currents and cold temperatures.

🎯How to use

Enter battery capacity in mAh, average current draw of your device, the efficiency of any voltage regulator/converter between battery and load, and the depth of discharge (how far you drain the battery before recharging).

💡Example scenario

10,000 mAh power bank, 500 mA load, 85% converter efficiency, 80% DoD: usable = 10000 � 0.80 � 0.85 = 6800 mAh. Run time = 6800/500 = 13.6 hours. Many power banks have an additional 20�30% internal overhead, so real-world may be 10�11 hours.

🏆Pro tip

For sleep-mode IoT devices, calculate average current: Iavg = (Iactive � t_active + Isleep � t_sleep) / (t_active + t_sleep). A device drawing 200 mA for 10ms every 10 seconds has Iavg � 0.2 mA � dramatically increasing battery life. Temperature also matters: Li-ion loses ~20% capacity at 0�C.