Summary of common power battery faults and related maintenance procedures

Latest update time：2023-10-07

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I have been writing about power batteries for a while. Today’s article will first give a general summary of the previous articles, and then summarize the common faults of power batteries and the correct maintenance procedures.

Power batteries are one of the core components of electric vehicles, affecting the performance, range, safety and reliability of the vehicle. They use chemical reactions to store and release electrical energy, providing power for electric vehicles through the charging and discharging process.

The performance parameters of power batteries include energy density, power density, cycle life, charging rate, etc., while influencing factors include battery chemical type, battery design and manufacturing, cycle depth, etc.

Fault diagnosis and repair are key to ensuring the normal operation of the power battery system. Fault diagnosis involves reading fault codes, sensor inspection, battery balancing, temperature monitoring, etc. to determine the cause of the problem. Repair methods include module replacement, cell replacement, maintenance, cooling system maintenance, etc., which require professional technology and equipment.

Common faults can be roughly divided into battery cell temperature being too high/too low fault, battery overcurrent discharge fault, battery internal resistance increase fault, battery cell voltage being too large fault, battery cell voltage being too high/too low fault, insulation fault, etc.

1. Insulation failure

Fault scope:

1. Battery manager;

2.Battery;

3. High voltage wiring harness;

Processing flow:

1. Use a megohmmeter to check the insulation status of the power battery;

2. Disconnect the battery manager and measure the lock fault range separately;

3. After eliminating the insulation fault, clear the fault code;

2. Increased internal resistance of the battery

Fault scope:

1. Battery manager;

2. Battery cells;

Processing flow:

1. Query abnormal information through diagnostic tools;

2. Replace the battery manager;

3. Repair or replace the corresponding high-voltage connecting copper busbar;

4. Replace the battery;

3. The battery cell voltage difference is too large

Fault scope:

1. Battery manager;

2. High voltage connection copper busbar;

3. Collect wire harness;

4. Battery cells;

Processing flow:

1. Read diagnostic information;

2. Check the high-voltage copper busbar bolts of the battery cell;

3. Replace the battery manager;

4. Replace the battery;

4. Battery over-current discharge

Fault scope :

1. Battery manager;

2. Current sensor;

3. High voltage wiring harness;

Processing flow:

1. Check the power battery assembly maintenance switch fuse;

2. Check the battery controller;

3. Check whether the high-voltage wiring harness is short-circuited;

4. Is the battery assembly short-circuited?

5. The battery cell voltage is too high

Fault scope:

1. Battery manager;

2. VCU;

3. Battery cells;

4. Poor connection or wiring harness;

Processing flow:

1. Check the number of abnormal battery cell through the diagnostic instrument;

2. Replace VCU;

3. Replace abnormal batteries;

6. The battery cell voltage is too low

Fault scope:

1. Battery manager;

2. Battery cells;

Processing flow:

1. Check the number of abnormal battery cell through the diagnostic instrument;

2. Replace VCU;

3. Replace abnormal batteries;

7. The battery cell temperature is too high

Fault scope:

1. Battery manager;

2. Battery cells;

3. Fan;

4. Temperature sensor;

5. Drive motor;

6. VCU

Processing flow:

1. Eliminate high current discharge in high temperature environment;

2. Provide 12V power to the battery assembly separately. If the fan operates normally, replace the battery manager;

3. If the fan is abnormal, check the fan-related wiring harness and fan assembly;

4. Use a diagnostic instrument to locate the abnormal temperature sensor and replace it;

8. The battery cell temperature is too low

Fault scope:

1. Temperature sensor;

2. The ambient temperature is too low;

Processing flow:

1. Eliminate the problem caused by low ambient temperature;

2. Use a diagnostic instrument to locate the abnormal temperature sensor and replace it;

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