Battery pack configuration determines how cells in series and parallel affect voltage, capacity, and energy. Series increases voltage; parallel increases capacity. Understanding the interaction lets you design packs for specific voltage rails and runtime requirements in RC, robotics, and portable electronics.
Cell Specifications
Li-ion: 3.7V, LiFePO4: 3.2V, NiMH: 1.2V, Lead-acid: 2V
Runtime Estimate
Pack Summary
How to Use the Battery Pack Calculator
This battery pack calculator computes pack voltage, total capacity in mAh, energy in Wh, and runtime for any series/parallel cell configuration. Enter your cell specs, then set the S and P count to see the pack performance.
Series vs Parallel Rules
Series (S) multiplies voltage but keeps capacity constant. Parallel (P) multiplies capacity but keeps voltage constant. A 3S2P pack with 3.7V/3000mAh cells gives: 11.1V (3 × 3.7V) at 6000mAh (2 × 3000mAh) = 66.6Wh. Total cells = 3 × 2 = 6 cells.
Common Configurations
RC cars use 2S–4S Li-ion packs (7.4V–14.8V). Drone racing uses 4S–6S (14.8V–22.2V) for high motor speed. Ebike packs are typically 10S–13S (36V–48V). Power tool batteries are 3S–5S (10.8V–18V). Electric scooters use 10S–13S at 5000–15000mAh (180–540Wh).
Safety Notes
All cells in a pack must be the same chemistry, brand, model, and ideally the same production batch. Mixing cells with different capacities or internal resistance causes uneven charging and can cause overcharge failures. Always use a BMS (Battery Management System) for Li-ion packs to prevent overcharge, overdischarge, and overcurrent.
FAQ
Is this battery pack calculator free?
Yes, completely free. Calculate pack specs for any configuration without any account or payment.
Is my data private?
All calculations run in your browser. No data is sent to any server.
How does a series battery configuration work?
In series, cells are connected positive-to-negative. Voltages add up but capacity stays the same as one cell. 4 cells × 3.7V = 14.8V pack, still same mAh as one cell. Used in RC cars, power tools, and any application needing higher voltage.
How does a parallel battery configuration work?
In parallel, cells are connected positive-to-positive. Voltage stays the same as one cell but capacity multiplies. 4 cells in parallel = 4× the mAh. Used to extend runtime while keeping the same voltage.
What does a 3S2P battery pack mean?
3S means 3 cells in series (voltage ×3). 2P means 2 of these series groups in parallel (capacity ×2). A 3S2P pack with 3.7V/3000mAh cells = 11.1V at 6000mAh = 66.6Wh total energy.
How do I calculate battery runtime?
Runtime (hours) = Pack Capacity (Wh) / Load Power (W). Or simplified for DC loads: Runtime (h) = Pack Capacity (mAh) / Load Current (mA). Actual runtime is 70-85% of theoretical due to battery discharge curves and efficiency losses.
What is the difference between mAh, Wh, and C-rating?
mAh measures charge capacity (1000mAh = 1Ah). Wh measures energy (Wh = V × Ah). C-rating indicates maximum discharge rate (1C for a 3000mAh cell = 3A, 2C = 6A). Higher C-ratings allow more current draw without damaging the battery.