Home Storage Batteries Experience Thermal Runaway? How to Choose a Safe Home Energy Storage Battery
Understanding Thermal Runaway in Batteries
Thermal runaway is a chain reaction triggered by various factors that can cause a battery's temperature to rise rapidly, potentially leading to fire or explosion. In lithium-ion batteries, in addition to normal charging and discharging reactions, there are many potential exothermic side reactions. When the battery temperature is too high or overcharged, it can easily be triggered.
Despite large-scale lithium-ion battery energy storage systems having transitioned from the "early commercialization" to the "large-scale development" stage, fires have occurred in large numbers across lithium-ion batteries on the generation side, grid side, and user side.
The root trigger for thermal runaway in lithium-ion battery systems lies in internal short circuits within the battery — such as insulation failures, aging, high summer temperatures, and direct contact between copper and aluminum at battery busbars — all of which can lead to overheating.
Choosing the Right Battery Model and Features to Avoid Safety Issues
"The characteristic parameters of lithium-ion batteries vary, and the early capture of thermal runaway is not accurate, leading to a lack of early warning for thermal runaway under energy storage operating conditions. We have verified several issues through 58 physical tests on batteries from different manufacturers: (1) electrical characteristic parameters of thermal runaway are insensitive and lagging; (2) fire and smoke alarms are not timely; (3) existing gas and chemical fire extinguishing agents cannot suppress re-ignition; (4) there are significant differences between mechanical/thermal-induced thermal runaway and charge/discharge thermal runaway." — Battery Researcher
Ensure That the Battery Has a Monitored BMS System
Every lithium battery has its corresponding BMS system and communication protocol. Before purchasing, confirm with the seller whether there is a monitoring app or upper-level computer software to track battery status in real time. This enables faster fault identification and more effective after-sales support.
- Temperature Monitoring & Control: Monitor the temperature of each individual cell in real time and trigger corresponding protection measures automatically.
- Battery Balancing: Prevent excessive voltage differences between cells, reducing the risk of local overcharging or over-discharging.
- Accurate SOC / SOH Estimation: Precise State-of-Charge and State-of-Health readings help avoid overcharging and over-discharging, reducing thermal runaway risk.
- Fault Diagnosis & Alarm: The BMS should detect internal short circuits, open circuits, and other faults promptly and issue alerts.
Thermal Management System and Shell Protection
- Heat Dissipation Design: The battery shell and internal structure should facilitate heat dissipation using air cooling, liquid cooling, or a combination of both.
- Shell Material: Use flame-retardant and high-temperature-resistant materials to slow fire spread. Battery shells are typically made of alloy materials offering good thermal conductivity and lighter weight — ideal for home use.
Battery Safety Protection Functions
| Protection Type | How It Works |
|---|---|
| Overcharge Protection | When charging voltage exceeds the set value, the circuit automatically cuts off to prevent thermal runaway. |
| Over-Discharge Protection | When discharge voltage drops below the set value, the circuit cuts off to prevent capacity decay. |
| Over-Current Protection | When current exceeds the rated value, the circuit cuts off automatically to prevent overheating. |
| Short-Circuit Protection | Short circuits trigger immediate circuit cutoff to prevent excessive current from damaging the battery. |
| Temperature Protection | Internal sensors stop charging or discharging when temperature goes too high or too low. |
| Reverse Polarity Protection | Prevents battery damage caused by reversed positive and negative pole connections. |
- Overcharge Protection: When charging voltage exceeds the set value, the circuit automatically cuts off to prevent thermal runaway.
- Over-Discharge Protection: When discharge voltage drops below the set value, the circuit cuts off to prevent capacity decay.
- Over-Current Protection: When current exceeds the rated value, the circuit cuts off automatically to prevent overheating.
- Short-Circuit Protection: Short circuits trigger immediate circuit cutoff to prevent excessive current from damaging the battery.
- Temperature Protection: Internal sensors stop charging or discharging when temperature goes too high or too low.
- Reverse Polarity Protection: Prevents battery damage caused by reversed positive and negative pole connections.
Certifications and Standards
Always ensure the product complies with national or international safety standards for energy storage batteries:
Mandatory for the European Union market. The CE mark indicates compliance with the basic requirements of relevant EU directives — a passport for products entering Europe.
A safety standard for rechargeable lithium-ion battery packs covering design, manufacturing, testing, and marking requirements.
