What are the common problems and solutions for power lithium-ion batteries

1. High battery voltage: After being fully charged, the voltage of a single string or several strings of batteries is clearly higher, and other cells are normal. The cause of the failure: ①acquisition error; ②the LMU equalization function is poor or invalid; ③the battery cell capacity is low, and the voltage rises faster during charging. Solution: ①The displayed value of the cell voltage is higher than that of the other cells. The actual voltage value of the measured cell is compared. If the actual value is lower than the displayed value and is the same as the voltage of other cells, the actual value will be used as the standard for the LMU The cell voltage is calibrated; if the measured value is consistent with the displayed value, the cell will be discharged and equalized manually. ②Check if the voltage sampling line is broken or not connected; ③Replace the LMU. 2. Low battery voltage: After fully charged and left to stand, the voltage of the battery or several cells is clearly low, and the other cells are normal. The cause of the failure: ①acquisition error; ② poor or ineffective LMU equalization function; ③ high cell self-discharge rate; ④ cell capacity is low, and the voltage drops faster during discharge. Solution: ①The displayed value of the cell voltage is lower than that of the other cells. Compare the actual voltage value of the measured cell. If the actual value is higher than the displayed value and is the same as the voltage of other cells, the actual value will be used as the standard for the LMU The cell voltage is calibrated; if the measured value is consistent with the displayed value, the cell will be charged and equalized manually. ②Check if the voltage sampling line is broken or not connected; ③Replace the LMU; ④Replace the faulty battery pack. 3. Pressure difference: dynamic pressure difference/static pressure difference. When charging, the cell voltage quickly reaches the full-charge cut-off voltage to jump the gun; when stepping on the accelerator, the cell voltage drops faster than other strings; when the brake is stepped on, the cell voltage rises faster than other strings. The cause of the failure: ①The copper plate fastening nut of the connected battery is loose; ②There is dirt on the connection surface; ③The self-discharge rate of the battery cell is large; ④The battery is welded to the copper plate to open the welding (causing the battery capacity of the string to be low); The core is leaking. Solution: ①Tighten the nut; ②Remove foreign objects on the connecting surface; ③Equalize the charge/discharge of the single string battery; ④Replace the problem battery pack. 4. Voltage jump: when the vehicle is running or charging, the cell voltage jumps. The cause of the fault: ①The connection point of the voltage acquisition line is loose; ②The LUM failure. Solution: ①Tighten the connection point; ②Replace the LMU. Temperature fault 1. Thermal management fault; ① Heating fault (heating film); when the temperature is lower than a certain value, the heating will not turn on during charging. The cause of the fault: ①The heating relay or BMU is faulty; ②The heating film or the power supply circuit of the relay is abnormal. Solution: ①Repair or replace the heating relay or BMU; ②Check and repair the power supply circuit. ②Heat dissipation failure (fan); the fan does not work when the temperature is higher than a certain value. The cause of the failure: ①The fan relay or BMU is faulty; ②The power supply circuit of the fan or the relay is abnormal. Solution: ①Repair or replace the fan relay or BMU failure; ②Check and repair the abnormality of the power supply circuit. 2. High temperature: One or several temperature points in the battery system are too high, and the alarm threshold is reached during operation or charging. The cause of the fault: ①The temperature sensor is faulty; ②LMU is faulty; ③The electrical connection is abnormal and localized heating; ④The fan is not turned on, and the heat dissipation is poor; ⑤Close to the motor and other heat sources; ⑥Overcharge. Solution: ①Measure the resistance value of the temperature sensor and compare the displayed value. If the actual value is lower than the displayed value and is the same as other temperature values, calibrate the LMU temperature value based on the actual value; ②Tighten the electrical connection point , Clear the foreign matter at the connection point; ③Ensure that the fan is turned on; ④Add insulation materials to isolate the heat source; ⑤Suspend operation to dissipate heat; ⑥Stop charging immediately; ⑦Replace the LMU. 3. Low temperature: One or several temperature points in the battery system are low, and the alarm threshold is reached during operation or charging. The cause of the fault: ①The temperature sensor is faulty; ②The LMU is faulty; ③The local heating element is abnormal. Solution: ①Measure the resistance value of the temperature sensor and compare it with the displayed value. If the actual value is higher than the displayed value and is the same as other temperature values, calibrate the LMU temperature value based on the actual value; ②Check and repair the heating plate; ③Replace the LMU. 4. Temperature difference; refer to the investigation method of high and low temperature. The difference in battery core heating. Charging failure 1. DC charging failure; GB/T27930-2015 charging cannot be started, charging jumps, and SOC does not reset after charging. The cause of the fault: ①Battery failure (abnormal voltage, temperature, insulation, etc.) ②BMU failure (abnormal charging module or charging CAN) ③Abnormal main negative and charging relay ④CC1 ground resistance, CC2 ground voltage abnormal ⑤PE ground abnormality solution: ①Troubleshoot Battery failure ②Repair/replace the failed parts ③Intercept the charging message and decompose the cause of the failure. 2. AC charging failure; the cause of the failure: ①Battery failure (abnormal voltage, temperature, insulation, etc.) ②BMU failure (abnormal charging module or charging CAN) ③Abnormal main negative and charging relay ④CC to ground resistance, CP to ground voltage abnormal ⑤PE ground Abnormal solution: ①Troubleshoot the battery failure ②Repair/replace the failed parts ③Intercept the charging message and decompose the cause of the failure. Disclaimer: Some pictures and content of articles published on this site are from the Internet. 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