This 18650 battery pack calculator is used to determine the optimal configuration of 18650 lithium-ion cells for a specific power requirement.
With a 12V battery pack with 10Ah capacity, the calculator would determine how many 18650 cells to connect in series for voltage and in parallel for capacity.
18650 Battery Pack Calculator
| Desired Voltage | Desired Capacity | Cell Capacity | Series Cells | Parallel Strings | Total Cells | Configuration | Actual Voltage | Actual Capacity | Total Power |
|---|---|---|---|---|---|---|---|---|---|
| 12V | 10Ah | 3000mAh | 4 | 4 | 16 | 4S4P | 14.8V | 12Ah | 177.6Wh |
| 12V | 20Ah | 2500mAh | 4 | 8 | 32 | 4S8P | 14.8V | 20Ah | 296Wh |
| 24V | 15Ah | 3500mAh | 7 | 5 | 35 | 7S5P | 25.9V | 17.5Ah | 453.25Wh |
| 24V | 30Ah | 3000mAh | 7 | 10 | 70 | 7S10P | 25.9V | 30Ah | 777Wh |
| 36V | 8Ah | 2500mAh | 10 | 4 | 40 | 10S4P | 37V | 10Ah | 370Wh |
| 36V | 12Ah | 3000mAh | 10 | 5 | 50 | 10S5P | 37V | 15Ah | 555Wh |
| 48V | 20Ah | 3000mAh | 13 | 7 | 91 | 13S7P | 48.1V | 21Ah | *1010.1Wh |
| 48V | 40Ah | 3500mAh | 13 | 12 | 156 | 13S12P | 48.1V | 42Ah | 2016Wh |
| 72V | 5Ah | 2000mAh | 20 | 3 | 60 | 20S3P | 74V | 6Ah | 444Wh |
| 72V | 10Ah | 2500mAh | 20 | 5 | 100 | 20S5P | 74V | 10Ah | 740Wh |
| 60V | 15Ah | 3000mAh | 16 | 5 | 80 | 16S5P | 60.8V | 15Ah | 912Wh |
| 36V | 18Ah | 3500mAh | 10 | 6 | 60 | 10S6P | 37V | 21Ah | 777Wh |
18650 Battery Pack Formula
Voltage calculation:
Total Voltage = Number of cells in series × Nominal cell voltageCapacity calculation:
Total Capacity = Number of parallel strings × Individual cell capacityPower calculation:
Total Power (Wh) = Total Voltage × Total Capacity
- Voltage: 18650 cells typically have a nominal voltage of 3.7V. To increase voltage, connect cells in series.
- Capacity: A single 18650 cell usually has 2000-3500mAh capacity. To increase capacity, connect cells in parallel.
- Power: Measured in watt-hours (Wh), it’s the product of voltage and capacity.
How do you calculate 18650 battery pack?
To calculate an 18650 battery pack configuration:
- Determine required voltage: Divide target voltage by cell voltage (3.7V) to get cells in series.
- Calculate capacity needs: Divide desired capacity by single cell capacity for parallel strings.
- Compute total cells: Multiply cells in series by parallel strings.
For a 24V, 10Ah pack using 3000mAh cells:
Cells in series: 24V ÷ 3.7V ≈ 6.49 (round up to 7)
Parallel strings: 10Ah ÷ 3Ah ≈ 3.33 (round up to 4)
Total cells: 7 × 4 = 28 cells
Final configuration: 7S4P (7 series, 4 parallel)
How many 18650 batteries to make 1 kWh?
To calculate cells for 1 kWh (1000Wh):
- Choose a voltage (e.g., 48V)
- Calculate capacity: 1000Wh ÷ 48V ≈ 20.83Ah
- Determine series cells: 48V ÷ 3.7V ≈ 13 cells
- Calculate parallel strings (using 3000mAh cells): 20.83Ah ÷ 3Ah ≈ 6.94 (round to 7)
Result: 13S7P configuration, totaling 91 cells (13 × 7)
How many 18650 batteries does it take to make 48V 20Ah?
For a 48V 20Ah pack:
- Series cells: 48V ÷ 3.7V ≈ 13 cells
- Parallel strings (3000mAh cells): 20Ah ÷ 3Ah ≈ 6.67 (round to 7)
Configuration: 13S7P, totaling 91 cells (13 × 7)
How many 18650 batteries would make a 12v 20Ah battery?
For a 12V 20Ah pack:
- Series cells: 12V ÷ 3.7V ≈ 3.24 (round to 4)
- Parallel strings (3000mAh cells): 20Ah ÷ 3Ah ≈ 6.67 (round to 7)
Configuration: 4S7P, totaling 28 cells (4 × 7)
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