🔋 Battery
This guide does not detail the creation of the battery, which I did at a professional's workshop. However, you will have access to the 3D model of the shell and all the information you need if you want to create your own or have it made by a professional. For the rest of the guide, I'll assume that you have a similar one. Mine is:
20S9P Battery Pack Specification (BAK INR2170-45D)
1. Configuration Details
- Cell Model: BAK INR2170-45D
- Number of Cells: 180 (20 in series, 9 in parallel)
- Series (S) Count: 20 (to reach the desired voltage)
- Parallel (P) Count: 9 (to increase capacity and current handling)
2. Electrical Specifications
- Nominal Voltage:
3.6V × 20 = 72V - Max Fully Charged Voltage:
4.2V × 20 = 84V - Min Discharge Voltage:
2.5V × 20 = 50V - Capacity per Cell:
- Rated: 4400mAh (4.4Ah)
- Typical: 4500mAh (4.5Ah)
- Total Battery Pack Capacity:
- Rated:
4.4Ah × 9 = 39.6Ah - Typical:
4.5Ah × 9 = 40.5Ah
- Rated:
- Total Energy Storage:
- Rated:
15.84Wh × 9 × 20 = 2851.2Wh(~2.85kWh) - Typical:
16.2Wh × 9 × 20 = 2916Wh(~2.92kWh)
- Rated:
3. Charging Parameters
- Standard Charging Current per Cell:
2.2A - Max Charging Current per Cell:
13.2A - Pack Standard Charging Current:
19.8A (2.2A × 9) - Pack Max Charging Current:
118.8A (13.2A × 9) - Charging Cut-off Voltage:
84V (4.2V per cell) - Charging Upper Limit Voltage:
85V (4.25V per cell, not recommended) - Ideal Cut-off Voltage:
60V (3.0V per cell)Maximizes lifespan and prevents deep discharge.
4. Discharging Parameters
- Standard Discharge Current per Cell:
880mA - Max Continuous Discharge Current per Cell:
30A - Peak Discharge Current (with temp cut at 80°C):
60A - Pack Max Continuous Discharge Current:
270A (30A × 9) - Pack Peak Discharge Current (with temp cutoff):
540A (60A × 9) - Discharge Cut-off Voltage:
50V (2.5V per cell) - Absolute Minimum Voltage:
40V (2.0V per cell, not recommended)
5. Thermal and Safety Limits
- Max Charging Temperature:
45°C - Min Charging Temperature:
0°C - Max Discharging Temperature:
60°C - Min Discharging Temperature:
-20°C - Max Allowed Surface Temperature:
- Charging:
55°C - Discharging:
80°C
- Charging:
- Internal Resistance per Cell:
≤5mΩ - Weight per Cell:
≤69g - Total Pack Weight (estimated):
~12.42 kg (180 × 69g)
6. Cycle Life
- 600 cycles with ≥60% capacity retention (≥2640mAh per cell)