How can you tell if your battery is still in a normal state?

When you have installed an energy storage system but are concerned about the battery's usage and want to know if the energy storage battery is working properly, what should you do as a non-professional? In fact, there are some simple daily inspection methods here. Although they are not professional testing procedures, they are suggested judgment methods that users can operate by themselves. They integrate multiple indicators of observation and detection. The following are the key judgment plans and steps:

Observe the appearance

1. Bulging and deformation: This is the most dangerous signal! Stop using it immediately and contact a professional. Any bulging means that the internal structure is damaged and there is a risk of fire and explosion
2. Leakage/odor: Check whether there is liquid leakage from the battery shell or a pungent chemical odor (such as acid, solvent). If so, immediately disconnect the power and isolate it for processing.
3. Corrosion/looseness at the connection point: Check whether there is white/green powder (corrosion), burn marks or looseness at the terminal, which will affect performance and safety.
4. Damaged shell: Any cracks or physical damage must be stopped immediately.

Monitor working status

1. Operating temperature: Does the shell temperature rise abnormally during charging and discharging? Normally, there should be a slight temperature rise based on the ambient temperature (usually not exceeding 45°C). Hot hands are a serious warning!
2. Abnormal noise: Is there any abnormal sound (such as sizzling, popping) when the battery is working? Normally, it should be very quiet.
3. BMS alarm/indicator: Does the system display or indicator light have alarms such as overvoltage, undervoltage, overtemperature, overcurrent, short circuit, etc.? Be sure to pay attention to any alarm!

Voltage detection

1. Voltage range after full charge: The voltage of a LiFePO4 battery after full charge is usually between 3.6V-3.65V. If the voltage after full charge is significantly lower or higher than this range, it may indicate that the battery is faulty or aged.
2. Voltage stability during discharge: During discharge, the voltage of a LiFePO4 battery should remain relatively stable without sudden voltage drops or fluctuations. If the voltage drops too quickly or fluctuates abnormally, it may mean that the battery's performance has degraded or there is an internal fault.
3. Consistency: Measure the voltage of each cell (if the battery pack design allows). The maximum voltage difference should be less than 0.05V (50mV), and more than 0.1V (100mV) indicates serious inconsistency and requires equalization or repair.

Capacity and life cycle

1. Comparison with nominal capacity: You can use professional battery capacity testing equipment to measure the actual capacity of the battery and compare it with the nominal capacity of the battery. If the actual capacity is significantly lower than the nominal capacity, it means that the battery may be aged or damaged.
2. Charge and discharge cycle test: Observe the capacity retention of the battery through multiple charge and discharge cycle tests. The theoretical cycle life of lithium iron phosphate batteries can reach thousands of charge and discharge times. If the capacity drops suddenly (such as a significant reduction in battery life) or charging is abnormal (unable to be fully charged) during actual use, battery aging should be considered.

Check the battery management system data

1. Read data through the BMS communication interface (such as RS485, CAN, Bluetooth):
2. Number of cycles
3. Historical maximum/minimum voltage, temperature
4. History of voltage and pressure difference of each cell
5. Charge and discharge ampere-hour count (used to estimate SOH)
6. Fault log

Important Tips

• Safety first! Wear protective equipment during operation to avoid short circuits. If you have any questions or find any abnormalities (especially bulging, leakage, overheating, smoking), stop using the device immediately and stay away, and seek professional help.
• Rely on BMS but don't blindly believe in it: BMS is a guardian, but it may fail. Regular manual inspections are important.
• Users should never disassemble the battery by themselves, and all tests should be performed in a power-off state. For batteries that are obviously bulging or leaking, they must be stopped immediately in a conspicuous way.