Lithium battery FCT test interpretation

Abstract: This paper discusses the Functional Circuit Test (FCT) test of lithium batteries in detail, covering the control mode, test items, test principles, test methods and other aspects of FCT test, and discusses its important role and application in lithium battery performance evaluation and quality assurance. Through the analysis of related technologies, it provides a reference for the research and development, production and application of lithium batteries.

I. Introduction

In order to ensure that the performance and quality of lithium batteries meet the requirements, various testing techniques have emerged, among which the Functional Circuit Test (FCT) test plays an important role in evaluating the functional integrity and reliability of lithium batteries.

Second, the control mode of the FCT test

1. Principle

The detection principle of FCT (Functional Circuit Test) is mainly based on the working principle of the current transformer. A current transformer is essentially a special type of transformer that is designed to convert a high current into a low current output in a specific proportion. It consists of a closed core and windings with good electromagnetic coupling properties. In the circuit to be tested, the FCT test achieves the current measurement by connecting the current transformer to the circuit under test. The measured secondary-side low-current signal is subsequently processed and analyzed to accurately reflect the original current in the circuit to be measured. In terms of fault current detection, FCT presets a range threshold for normal current.

When the measured current value is outside this normal range, it indicates that there may be a fault in the circuit under test, such as a short circuit that can cause an abnormal increase in current, and an open circuit that can cause a sudden current dip. By keenly capturing current changes and comparing them to preset thresholds, FCT is able to quickly and accurately identify fault conditions in a circuit. In addition, in order to evaluate the functional state of the circuit more comprehensively and accurately, FCT often combines other measurement techniques and parameters, such as voltage measurements, resistance measurements, and detailed analysis of various signals in the circuit. This multi-dimensional comprehensive detection method can deeply understand the operation characteristics of the circuit from different angles, find potential problems or abnormalities in time, and provide strong support and basis for the optimal design, fault diagnosis and maintenance of the circuit.

Based on the use of current transformers, FCT provides an efficient, accurate, and safe solution for functional integrity and reliability testing of electronic circuits.

2. MCU control mode

The MCU (Micro Control Unit) control method is characterized by fast execution speed in FCT testing. It enables precise timing control of the test process through pre-programmed control programs. This approach requires dedicated circuit design and program development for specific test needs.

3. Embedded CPU control mode

The embedded CPU control mode has a strong scheme targeting, and can be customized according to the specific characteristics and test requirements of lithium batteries. At the same time, it is relatively easy to modify the control program, which helps to quickly optimize the test process.

4. PC control mode

The PC control method is widely used in FCT testing. Based on the maturity and ubiquity of PC technology, it has significant advantages such as low price, convenient file processing and data output, and close to user operating habits. Through the software interface on the PC, the tester can intuitively set the test parameters, monitor the test process, and analyze the test results.

5. PLC control mode

PLC (programmable logic controller) control mode has high reliability and stability in the field of industrial control. In the FCT test of lithium batteries, it is suitable for scenarios with harsh test environments, complex test processes, and high reliability.

3. FCT test items

1. Insulation test

It is used to test the insulation performance between the positive and negative electrodes of the lithium battery and between the shell to ensure that the battery will not leak during use and ensure the safety of users.

2. Withstand voltage test

By applying a high voltage higher than the normal operating voltage, the insulating material and structure of the lithium battery can withstand the instantaneous high voltage impact and prevent breakdown failure under abnormal conditions.

3. Resistance test

This includes the measurement of the internal resistance of the battery and the contact resistance of the electrodes. The magnitude of the internal resistance directly affects the charge-discharge performance and efficiency of the battery, while the electrode contact resistance reflects the quality of the battery assembly.

4. Load performance test

Simulate the load situation in actual use, evaluate the output voltage, current and power characteristics of lithium battery under different load conditions, and verify its stability and reliability under working conditions.

5. Hall characteristic test

For the lithium battery management system using Hall sensors, the performance of Hall elements is tested to ensure accurate measurement and control of battery current.

6. Missing phase detection

It is used in multi-phase lithium battery system to check whether the connection and operation between each phase are normal, and to prevent the performance degradation or failure of the entire battery system due to the absence of a certain phase.

Fourth, FCT test method

1. Connect the instrument

First of all, according to the items to be tested, the lithium battery is correctly connected with the test instrument to ensure that the circuit connection of all test items is normal and the polarity is accurate. This is a fundamental step to ensure the accuracy and reliability of the test results, and any connection errors can lead to test failures or incorrect conclusions.

2. Start measuring

SELECT THE BUILT TEST SOLUTION ON NANOSOFT'S ATECLOUD TEST SYSTEM PLATFORM, SELECT THE REQUIRED TEST ITEMS, TEST SINGLE OR MULTIPLE PROJECTS AT THE SAME TIME, AND THEN START THE TEST PROGRAM.

3. Data collection

During the test, the system collects various test data in real time, including voltage, current, resistance and other parameters. The accuracy and completeness of this data is crucial for subsequent analysis and judgment.

4. Data processing

Initial processing of the acquired data, such as noise removal, calibration of measurement errors, etc., is carried out to improve the quality and usability of the data.

5. Data analysis

Statistical analysis, trend analysis and other methods are used to dig deep into the processed data to find out the rules and outliers in the data. By comparing with standard values or preset thresholds, it is judged whether the performance of the lithium battery meets the requirements.

6. Result output

The results of the analysis are presented to the tester in a clear and intuitive way, such as numbers, curves, graphs, etc. At the same time, the test results and analysis reports can be exported to provide a basis for subsequent quality evaluation and improvement.

VII. Conclusions

FCT testing of lithium batteries is an important part of ensuring their performance and quality. By reasonably selecting the control mode, clarifying the test items, understanding the test principle and following the correct test method, the potential problems in the function of the lithium battery can be effectively detected, and the reliable application of the lithium battery can be provided with strong support. With the continuous development of lithium battery technology and the continuous expansion of application fields, FCT testing technology will also continue to innovate and improve to meet higher performance requirements and stricter quality standards. In summary, a comprehensive and accurate FCT test for lithium batteries is of irreplaceable significance to ensure their safe and efficient applications in various fields.

Article source: lithium battery technology knowledge platform

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