Tools · Battery & Power
🔋 Battery & Power Budget
Estimate how long a battery will run your circuit, work out series/parallel pack voltage and capacity, and total up a multi-device power budget. Practical bench math for any battery-powered build.
Battery Life Estimator
The basic estimate is capacity divided by load current. Real batteries never deliver 100% of rated capacity, so a derating factor gives a more honest number.
Life (hours) = (Capacity_mAh / Load_mA) × derating
mAh
mA
V
Why derate? Rated capacity is measured at a slow, ideal discharge. Higher currents, cold temperatures, and aging all reduce usable capacity (Peukert's effect). 0.7–0.85 is a realistic planning range for most builds.
Battery Pack Builder
Cells in series add voltage (capacity stays the same). Cells in parallel add capacity (voltage stays the same). A series-parallel pack does both.
V_pack = V_cell × series · Capacity = Cap_cell × parallel
V
mAh
Naming: a "3S2P" pack means 3 cells in series, 2 in parallel (6 cells total). Common in lithium packs — the S count sets voltage (3S Li-ion ≈ 11.1 V nominal), the P count sets runtime.
Multi-Load Power Budget
List each device drawing from your supply or battery. The tool totals the current and power, then estimates runtime from a battery capacity. Edit any row; add or remove loads as needed.
V
Load nameCurrent (mA)Qty
mAh