Battery Life Calculator
Estimate how long a battery will last given its capacity and the load current draw.
mAh
mA
%
Battery Life
11.3 hours
Battery Life (days)0.47 days
Usable Energy (at 3.7 V)6.29 Wh
Battery Life vs Battery Capacity
Battery Life Estimation
Formula
Life (hours) = Capacity (mAh) x Efficiency / Load (mA)
Efficiency accounts for losses from the battery internal resistance, DC-DC conversion, and temperature effects. Typical Li-ion efficiency is 80-90%.
Example Calculation
2000 mAh battery, 150 mA load, 85% efficiency.
- 01Usable capacity = 2000 x 0.85 = 1700 mAh
- 02Life = 1700 / 150 = 11.3 hours
- 03Life in days = 11.3 / 24 = 0.47 days
Frequently Asked Questions
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