Battery Series Parallel Calculator
Calculate lithium battery pack series/parallel configuration with S/P output and safety recommendations
WARNING: DIY Battery Packs Pose Serious Safety Risks
- Lithium batteries can cause fire or explosion if mishandled
- Battery pack assembly requires professional knowledge and proper equipment
- Lithium battery transport is regulated (UN38.3, IATA DGR)
- Strongly recommended: Purchase pre-built modules or seek professional services
If you still choose DIY, ensure you have:
- ✓ Proper spot welder (NOT soldering iron)
- ✓ Insulation materials (fish paper, heat shrink)
- ✓ Fire extinguisher (Class D for metal fires)
- ✓ Well-ventilated workspace
- ✓ Safety glasses and gloves
Battery Type Selection
Quick Battery Selection
18650 High Capacity (1-3C)
18650 Balanced (5-8C)
18650 High Power (10C+)
21700 Capacity/Power
LiFePO4 Storage/Power
Cell Specifications
Target Configuration
Calculation Results
* Rough estimate; real range varies up to ±50% with load, grade, wind, and riding style
※ BMS current rating should have 20% safety margin
Application Recommendation
Suitable Applications:
Recommended Batteries (click to apply):
Automatically matches applications and batteries based on C-rate
※ Nickel strip calculated at conservative 5A/mm²
Battery Configuration Diagram
Cost / Weight Distribution
* Costs are rough global estimates (USD) for material-share reference only, not local quotes
Next step: pair with these tools
About Battery Series Parallel Calculator
Battery Series Parallel Calculator is a free online tool designed for DIY battery pack builders. Whether you're building an e-bike battery, solar storage system, or other projects, this calculator helps you determine the correct S/P configuration.
Calculator Features
- S/P Configuration: Enter target voltage and capacity to calculate series (S) and parallel (P) counts
- Multiple Battery Types: Supports 18650, 21700, LiFePO4, NiMH, LTO and more
- Nickel Strip Calculation: Calculate required nickel strip specs based on max current to prevent overheating
- AWG Wire Recommendation: Provides suitable wire gauge based on NEC standards
- BMS Specifications: Overcharge/overdischarge protection voltage and current recommendations
- Visual Configuration: Intuitive diagram showing series/parallel battery arrangement
Calculation Formulas
This calculator uses the following formulas:
- Series Count (S) = Target Voltage ÷ Cell Nominal Voltage
- Parallel Count (P) = Target Capacity ÷ Cell Capacity
- Total Cells = S × P
- Total Energy (Wh) = Nominal Voltage × Total Capacity
- Max Current (A) = Cell Capacity (Ah) × C-rate × P
Safety Precautions
- Lithium batteries can cause fire or explosion if mishandled
- Use a proper spot welder, NEVER solder directly to batteries
- Always wear safety glasses and gloves when assembling
- Have a Class D fire extinguisher ready for metal fires
- Ensure proper ventilation in your workspace
Frequently Asked Questions
Q: What does S/P configuration mean?
S stands for Series, P stands for Parallel. For example, 13S4P means 13 cells in series forming one string, with 4 strings in parallel. Series increases voltage, parallel increases capacity.
Q: What does C-rate mean?
C-rate indicates the discharge rate relative to battery capacity. 1C means discharging at a current equal to the capacity. For a 3000mAh battery, 1C = 3A. 10C would be 30A discharge.
Q: Why is nickel strip calculation important?
Nickel strips connect battery cells. If current capacity is insufficient, they can overheat and cause fire. This calculator uses a conservative 5A/mm² rating for safety.
Q: Is a BMS necessary?
Yes, a BMS (Battery Management System) is essential for lithium battery packs. It provides overcharge, overdischarge, and overcurrent protection, as well as cell balancing.
Data Sources
Formulas and data verified from: Battery University, Samsung SDI battery specifications, LG Energy Solution technical documents, NEC National Electrical Code.
Last updated: November 2025 | This calculator is for reference only. Consult professionals for actual assembly.
