For the detection of fixed double-layer capacitors (supercapacitors) for electronic devices, the following methods can be mainly used:

1. Appearance and size inspection
Appearance inspection: Visually inspect the appearance of the capacitor to ensure that its surface is flat and smooth, without scratches, cracks, burn marks or deformation.
Size inspection: Check the size of the capacitor, including length, width, height, etc., to ensure that it meets the values ​​specified in the detailed specifications.
2. Electrical performance test
Constant current charge and discharge method
Principle: Use a stable constant current source to charge the capacitor, and determine the capacitance by measuring the voltage change of the capacitor. After charging is completed, use the opposite voltage to drive the capacitor to discharge, and also determine the capacitance by measuring the voltage change of the capacitor. In addition, the charging and discharging time of the capacitor and the resistance value need to be calculated to calculate the capacitance value.
Application: This method is suitable for measuring the capacitance and internal resistance of the capacitor, and is one of the commonly used methods in the detection of fixed double-layer capacitors for electronic devices.
AC impedance method
Principle: Use an AC signal of a certain frequency to excite the capacitor and measure the resistance and inductance of the capacitor bypass. By measuring the impedance size and phase difference of the capacitor, the capacitance of the capacitor is calculated.
Application: This method is suitable for relatively large capacitance, but in practical applications, it is necessary to pay attention to the selection of appropriate frequency and test conditions.
Static capacitance test
Principle: Use the LRC tester to test the capacitor for static capacitance, and judge whether the capacity of the capacitor meets the requirements according to the displayed results.
Application: This method is mainly used to test the quality of the capacitor to ensure that its capacitance value is within the specified range.
3. Environmental adaptability test
Temperature cycle test: The capacitor is placed under the specified temperature and humidity conditions for cycle testing to evaluate its performance stability under different environmental conditions.
Humidity test: Test the capacitor under the specified humidity conditions to check whether it is damp or has other adverse effects.
4. Safety test
Insulation test: Place the two electrodes of the capacitor in a high-voltage chamber, apply different high voltages within the specified time, and then observe the change of the leakage current of the capacitor to judge its insulation performance.
Leakage current test: The leakage current value of the capacitor in the working state is measured by a precision ammeter to evaluate its impact on the power grid system and ensure its safety and stability to the power grid system.
5. Other tests
Cycle life test: Through the charge and discharge cycle test, the capacitance change of the capacitor is continuously recorded to evaluate the number of charge and discharge times and service life it can withstand.
Impact test: The capacitor is subjected to impact and vibration tests to check the impact and vibration it can withstand in electronic equipment to ensure its reliability and stability during use.
In the actual detection process, it is necessary to select appropriate test methods and test conditions according to the specific type, specification and application scenario of the capacitor. At the same time, it is also necessary to strictly control the experimental conditions to ensure measurement accuracy and repeatability.