Battery Pack Configurator
Design custom Li-Ion packs (S/P configuration).
Designing a Custom Battery Pack
When off-the-shelf batteries don't meet your needs, you build a custom pack. This calculator helps you design a battery pack using individual cells (like the popular 18650 or 21700 Li-Ion cells) to achieve specific Voltage and Capacity targets.
Configurations are described using "S" and "P" notation (e.g., 10S4P). "S" stands for Series (voltage) and "P" for Parallel (capacity). This design process is fundamental for building batteries for e-bikes, RC drones, power walls, and electric skateboards.
Configuration Formulas
To reach your goals, you arrange cells in blocks.
Series Count (S) = Target Voltage / Cell Voltage
Parallel Count (P) = Target Capacity / Cell Capacity
Example: 48V e-Bike Battery
Using standard cells (3.6V, 2500mAh) to build a 48V, 10Ah pack:
- Series Steps: 48V / 3.6V = 13.3 → Round to 13S (creates 46.8V nominal).
- Parallel Groups: 10Ah / 2.5Ah = 4P.
- Total Cells: 13 × 4 = 52 cells.
Applications
- Personal Electric Vehicles (PEVs): Custom packs for Onewheels, scooters, and e-bikes to maximize range or torque.
- Power Walls: Storing solar energy using recycled high-capacity cells arranged in large parallel blocks (e.g., 14S80P).
- Robotics: Creating high-discharge packs (high C-rating) for fighting robots or industrial AGVs.
FAQ
Do I need a BMS?
YES. ABSOLUTELY. A Battery Management System (BMS) is mandatory for Lithium packs. It monitors individual Series groups to prevent over-charging (fire risk) and over-discharging (permanent damage). It also balances the cells to keep the pack healthy.
Can I mix old and new cells?
No. Your pack is only as strong as its weakest cell. If you mix capacities, the weak cell will drain first, triggering the BMS to shut down the entire pack early. Always use matched cells from the same batch.
what is current capacity (C-rating)?
Parallel connections increase the current capability. If one cell can handle 10A continuous discharge, a 4P block can handle 40A. This is crucial for high-power applications like electric vehicles.