1. Safety preparations
- Ventilation first
- Lead-acid batteries emit hydrogen gas (explosion limit 4% to 75%) when charging, so the charging area must be well ventilated. Otherwise, a spark could blow up the workshop.
- Lithium batteries do not pose a hydrogen risk, but high temperatures could trigger thermal runaway, so ventilation is also crucial.
- Personal protective equipment (PPE)
- Lead-acid batteries: acid-resistant gloves + goggles + acid-resistant apron (electrolyte is sulfuric acid, which will burn through skin if it gets on it).
- Lithium batteries: Insulated gloves + fire blanket (to protect against thermal runaway).
- Environmental inspection
- No smoking in the charging area. Fire extinguishers must be dry powder or CO₂ types (water-based extinguishers are ineffective against lithium fires).
2: Check before charging
- Lead-acid battery
- electrolyte level: must cover the plates (below standard? Add distilled water, not tap water!).
- Case condition: cracks/leaking? Immediately decommission, sulfuric acid running onto the floor is like planting a landmine.
- Lithium battery
- BMS status: check battery management system (BMS) no alarm, voltage consistency deviation > 0.1V? Send for repair, don’t charge hard.
- Appearance: bulging/deformation? Isolate immediately, a bulging lithium battery is a time bomb.
- Forklift power failure
- Turn off the key switch and unplug the load (plugging in the charger while it is live? Just wait for the interface to burn).
3. Charger Connection Procedures
Technology-Specific Protocols
Lead-Acid Charging:
- Sequence: Connect battery terminals first → Plug into AC power (prevents spark-induced hydrogen ignition).
- Charger Type: Use temperature-compensated chargers (Δ-0.03V/°C adjustment prevents overcharging).
Lithium Charging:
- Communication Protocol: Ensure CAN bus/RS485 communication between charger and BMS. Generic chargers may bypass safety cutoffs.
- Voltage Alignment: Match charger output to battery nominal voltage (e.g., 48V LiFePO4 requires 54.6V±0.5V charger).
Common Error to Avoid:
- Never interchange charger types. A 30V lithium charger used on 24V lead-acid batteries may cause catastrophic failure.
4. Real-Time Charging Monitoring
Performance Metrics Comparison
| Metric | Lead-Acid | Lithium |
| Temperature | Alarm threshold: 50°C (122°F) | Alarm threshold: 45°C (113°F) |
| Charge Stages | Bulk → Absorption → Float | CC → CV → Termination (BMS-controlled) |
| Voltage Deviation | ≤5% between cells | ≤0.1V between cells (critical) |
Intervention Triggers:
- Lead-Acid: If voltage exceeds 2.4V/cell during absorption phase, initiate cooldown.
- Lithium: Immediately stop charging if any cell reaches 4.25V (Li-ion) or 3.65V (LiFePO4).
5. Post-Charging Best Practices
Battery-Specific Handling
Lead-Acid:
- Equalize monthly: Apply 2.5V/cell for 2-3 hours to prevent sulfation.
- Reinstall only after 30-minute rest period (acid stratification mitigation).
Lithium:
- Storage SOC: Maintain 30-50% charge for long-term inactivity (full charge accelerates SEI layer growth).
- Post-charge voltage check: Confirm all cells within 0.05V difference before reuse.
Emergency Response Quick Reference
Lead-Acid Incident:
- Acid spill: Neutralize with baking soda (1kg per 5L spilled acid), then flush with water.
- Hydrogen smell: Evacuate and ventilate for 30+ minutes before investigation.
Lithium Incident:
- Thermal runaway: Submerge in water ONLY if battery is <32V. High-voltage packs require Class D extinguishers.
- Damaged cells: Place in fire-resistant container with vermiculite sand, quarantine for 48h.
References:
- Lead-Acid: IEEE 1188-2005 (Maintenance Standard)
- Lithium: IEC 62619-2017 (Safety Requirements for Industrial Batteries)
This guide synthesizes 20 years of field experience with global safety regulations to maximize battery lifespan and minimize operational risks. Always consult manufacturer documentation for model-specific requirements.
