Pack Battery Pack Connection Method And Precautions

**Connection Methods for Lithium-Ion Battery Packs in Service Robots**  

### **1. Connection Methods**  

#### **A. Series Connection**  

- **Purpose**: Increases total voltage.  

  Example: Connecting four 3.7V cells in series yields 14.8V.  

- **Configuration**:  

  - Positive terminal of Cell 1 → Negative terminal of Cell 2.  

  - Repeat until all cells are connected.  

- **Applications**: Used when higher operating voltage is required (e.g., robot motor systems).  

#### **B. Parallel Connection**  

- **Purpose**: Increases total capacity (Ah).  

  Example: Four 2000mAh cells in parallel yield 8000mAh.  

- **Configuration**:  

  - All positive terminals connected together; all negative terminals connected together.  

- **Applications**: Used for extended runtime (e.g., long-duration service robots).  

#### **C. Series-Parallel Hybrid Connection**  

- **Purpose**: Balances voltage and capacity requirements.  

  Example: 2S2P (two cells in series + two in parallel) → 7.4V and 4000mAh.  

#### **D. BMS (Battery Management System) Integration**  

- **Wiring**:  

  - Voltage sense wires: Connect to each cell’s terminals for balancing.  

  - Temperature sensors: Attach to critical points (e.g., cell surfaces).  

  - Power terminals: Link to main positive/negative outputs.  

- **Critical Role**: Monitors and protects against overvoltage, undervoltage, and overtemperature.  

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### **2. Key Considerations**  

#### **A. Electrical Safety**  

1. **Polarity Check**:  

   - Double-check terminal markings (+/-) to avoid reverse polarity.  

   - Use color-coded cables (e.g., red for positive, black for negative).  

2. **Insulation**:  

   - Ensure terminals are insulated to prevent accidental short circuits.  

   - Apply heat shrink tubing or insulating tape to exposed metal.  

3. **Uniform Cells**:  

   - Use cells with identical capacity, voltage, and internal resistance.  

   - Avoid mixing cells from different manufacturers or batches.  

#### **B. Mechanical Robustness**  

1. **Secure Connections**:  

   - Use welded joints, bolts, or high-quality connectors (e.g., Anderson SB/XT90).  

   - Prevent loose connections that could cause arcing or heat buildup.  

2. **Vibration Resistance**:  

   - Reinforce solder points and wiring in robots exposed to frequent movement.  

   - Follow SJ/T 11852-2022’s vibration/shock test standards.  

#### **C. Thermal Management**  

1. **Heat Dissipation**:  

   - Avoid stacking cells tightly; leave gaps for airflow.  

   - Use thermally conductive materials (e.g., aluminum housings).  

2. **Temperature Monitoring**:  

   - BMS must trigger shutdown if cells exceed safe limits (e.g., >60°C).  

#### **D. BMS Calibration**  

- **Voltage Balancing**:  

  - Regularly calibrate the BMS to ensure accurate cell balancing.  

  - Address cell voltage deviations promptly to prevent overcharging.  

#### **E. Environmental Protection**  

- **IP Rating**:  

  - Seal battery packs to meet required ingress protection (e.g., IP54 for dust/moisture resistance).  

- **Avoid Humidity**:  

  - Store and operate in environments below 90% relative humidity (RH).  

#### **F. Transport and Storage**  

1. **Transport Compliance**:  

   - Follow UN 38.3 regulations (e.g., partial state of charge: 30–50% SOC).  

2. **Storage Conditions**:  

   - Store at 10–25°C; avoid prolonged exposure to extreme temperatures.  

#### **G. Testing and Certification**  

- **Post-Assembly Tests**:  

  - Conduct capacity verification, insulation resistance, and short-circuit tests.  

  - Validate compliance with SJ/T 11852-2022 and IEC 62133 standards.  

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**Final Tip**: Always refer to the manufacturer’s guidelines and SJ/T 11852-2022 for service robot-specific requirements. ⚠️