Battery Life Calculator
Estimate how long a battery lasts from its capacity in mAh and the load current it drives.
Battery life17.00hrs
In days0.71days
Run time ≈ capacity (mAh) ÷ load (mA), then scaled by an efficiency factor for real-world losses. A 2000 mAh battery driving 100 mA gives 2000 ÷ 100 = 20 hours in ideal terms; at 85% efficiency that is ≈ 17 hours. Real life is shorter still — current spikes, self-discharge, temperature and the cut-off voltage all eat into capacity, so treat this as an upper-bound estimate.
Questions
How do I calculate battery life?
Divide the capacity in mAh by the load in mA to get hours. A 2000 mAh battery at 100 mA lasts about 2000 ÷ 100 = 20 hours before real-world losses.
Why is the real battery life shorter?
Datasheet capacity assumes ideal conditions. Current spikes, self-discharge, cold temperatures and converter inefficiency all reduce usable capacity, so apply an efficiency factor below 100%.