Lithium battery packs are dangerous goods, how to ensure their safe, stable and long-life operation, which requires our design engineers, for different products and use scenarios to set the protection system;
1.Overcharge Protection
- Function:Prevent the battery voltage from exceeding the set upper limit (usually 4.2V/unit).
- Reason:Overcharging will lead to uncontrolled chemical reaction inside the battery, which may cause heat generation, expansion, liquid leakage or even explosion.
- Realization:Monitor the voltage through the BMS and cut off the charging circuit when the upper limit is reached.
2. Over-discharge Protection
- Function: Prevent the battery voltage from falling below the set lower limit (usually 2.5V-3.0V/single cell).
- Reason: Over-discharge will cause damage to the internal structure of the battery, capacity drop, or even unable to charge.
- Realization: BMS cuts off the discharge circuit when the voltage is too low.
3. Overcurrent Protection
- Function: Prevent the battery from overcurrent when discharging or charging.
- Reason: Overcurrent will cause the battery to heat up, performance degradation, and even lead to thermal runaway.
- Realization: BMS detects the current and cuts off the circuit when it exceeds the set value.
4. Short Circuit Protection
- Function: Prevent the positive and negative terminals of the battery from being directly short-circuited.
- Reason: Short circuit will generate a great current, leading to rapid heating of the battery, which may cause fire or explosion.
- Realization method: BMS will quickly cut off the circuit when it detects a short circuit.
5. Temperature Protection
- Function: Prevent the battery from working under too high or too low temperature.
- Reason:High temperature: may lead to electrolyte decomposition, increase in internal resistance, or even thermal runaway.
Low temperature: may lead to battery performance degradation, lithium precipitation during charging, and damage to the battery.
- Realization method: BMS monitors the battery temperature through temperature sensor and stops charging and discharging when the temperature exceeds the range.
6. Equalization Protection (Cell Balancing)
- Function: Ensure the voltage of each single cell in the battery pack is the same.
- Reason: Inconsistency of voltage between cells will lead to overcharging or overdischarging of some cells, affecting the overall performance and life.
- Realization: BMS adjusts the voltage of each single cell through active or passive balancing technology.
7. Overvoltage Protection (Overvoltage Protection)
- Function: Prevent the total voltage of the battery pack from exceeding the safe range.
- Reason: Overvoltage may cause damage to the battery pack or safety problems.
- Realization: BMS monitors the total voltage and cuts off the circuit when it exceeds the set value.
8. Undervoltage Protection
- Function: Prevent the total voltage of the battery pack from being too low.
- Reason: Undervoltage may cause the battery pack can not work normally, or even damaged.
- Realization: BMS monitors the total voltage and cuts off the circuit when it is lower than the set value.
9. Reverse Polarity Protection
- Function: Prevent the positive and negative terminals of the battery from being reversed.
- Reason: Reverse connection may lead to short circuit or damage of the battery.
- Realization: Reverse polarity protection is realized by circuit design or BMS.
10. Mechanical Protection
- Function: To prevent the battery from physical damage.
- Reason: Mechanical damage may lead to short circuit, liquid leakage or fire inside the battery.
- Realization: Use of strong shell, cushioning materials ,anti-vibration design and waterproof design..
11. Communication and Monitoring
- Function: Real-time monitoring of battery status (voltage, current, temperature, capacity, etc.
- Reason: Timely detection of problems to avoid potential safety hazards.
- Realization: Communicate with external devices (e.g. charger, controller) through BMS to provide data and take corresponding measures.