Preventing thermal runaway in lithium-ion batteries

Thermal runaway in lithium-ion batteries, especially in high-performance ebikes, is a safety and longevity issue. Thermal runaway happens when a cell’s temperature increases rapidly and can trigger a chain reaction that can lead to a fire or explosion. Here are some ways to prevent thermal runaway:

1. Use Good Cells

• Cell Selection: Use good cells, like Molicel P45B, that have less defects and are known for better thermal stability.

• Matching Cells: Make sure all cells in a battery pack are matched in capacity and internal resistance so you don’t get uneven charging or discharging which can cause overheating.

2. Use Advanced Battery Management Systems (BMS)

• Temperature Monitoring: A good BMS monitors the cell temperature and cuts off power if the temperature exceeds a safe limit.

• Overcharge and Overdischarge Protection: The BMS should protect against overcharging and over-discharging which can cause heat buildup.

3. Thermal Management

• Heat Dissipation Design: Use materials that can dissipate heat well, like PET-GCF and ASA, for battery enclosures.

• Cooling Solutions: Passive cooling like heatsinks or thermal pads or active cooling like fans or liquid cooling for high power applications.

4. Limit Current

• Controller Settings: Adjust the controller settings to prevent excessive current draw that can cause cells to overheat. High-performance ebikes should be configured to balance power and safety.

• Load Management: Avoid long periods of full load as this can cause cells to heat up fast.

5. Use Protective Materials and Enclosures

• Epoxy Resin Coating: Apply epoxy resin coating to the battery pack to contain and slow down thermal propagation in case of a single cell failure.

• Physical Barriers: Use materials that act as thermal barriers between cells to prevent a single cell’s thermal runaway from affecting the others.

6. External Damage

• Proper Mounting: Mount the battery securely to the bike to prevent physical damage from vibration or impact which can cause short circuits and thermal runaway.

• Protective Enclosures: Use rugged enclosures that can withstand external shocks and protect cells from punctures or crush injuries.

7. Regular Inspection and Maintenance

• Regular Check-Ups: Check battery packs regularly for damage, swelling or overheating. Remove damaged cells immediately to prevent issues.

• Balanced Charging: Balance charge the battery regularly to ensure all cells are equally charged and avoid imbalances that can cause thermal runaway.

8. Charging Practices

• Overcharging: Use chargers with overcharge protection. Don’t leave batteries unattended or charging overnight.

• Temperature Monitoring: Charge batteries within the recommended temperature range. Extreme temperatures can degrade cells and increase thermal runaway risk.

By following these tips you can minimize thermal runaway risk and make your ebike conversion kits and battery packs safer. For customers who want to add extra protection to their batteries, offer them epoxy resin coating service or recommend good cells like Molicel P45B which are known for stability and reliability.