Thermal Battery Impedance Testing for Defect Detection
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Solution Overview
Problem
Existing methods for testing thermal batteries are often destructive and fail to assess the quality of components and connections within the battery, limiting the ability to detect defects such as poor welds or other out-of-specification conditions.
Innovation Solution
A non-destructive testing method involving impedance, reactance, and capacitance measurements using a sinusoidal voltage source to determine if a thermal battery is 'in family' or 'out of family' by comparing measured values to reference standards, identifying deviations that indicate defects or out-of-specification conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If insulation resistance test is used to test thermal batteries, then the testing process is simple and quick, but the test can only disclose the existence of a short circuit and cannot detect the quality of components or connections
Solution Approach 1:
The patent changes the testing parameter from simple insulation resistance measurement to impedance measurement at multiple frequencies. By measuring impedance across a frequency range and analyzing the data to extract equivalent circuit parameters (resistance, inductance, capacitance), the method achieves both rapid testing and detailed defect detection capability, resolving the contradiction between testing speed and detection precision.
2Measurement precision
If destructive testing is used to test thermal batteries, then the quality of components and connections can be assessed, but the battery is destroyed and cannot be used
Solution Approach 1:
The patent replaces destructive mechanical/chemical testing methods with non-destructive electrical impedance spectroscopy. By applying small AC voltage signals and measuring the resulting current response across multiple frequencies, the method extracts detailed information about internal components and connections without activating the battery or causing any physical damage, thus maintaining battery usability while achieving precise quality assessment.
3Device complexity
If traditional testing methods are used, then the testing process is simple, but poor weld connections and out-of-specification conditions cannot be detected
Solution Approach 1:
The patent adds the frequency dimension to the testing process by measuring impedance across multiple frequencies rather than at a single point. This dimensional expansion allows the extraction of multiple equivalent circuit parameters that provide detailed insights into different aspects of battery quality, including weld connections and component integrity, while maintaining manageable system complexity through automated data analysis.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for the identification of defective thermal batteries without destruction, reducing waste and improving quality control by accurately distinguishing between 'in family' and 'out of family' batteries through impedance, reactance, and capacitance analysis, thereby enhancing production efficiency and reducing false positives.
Implementation Method 1
measuring an impedance across two terminals of the thermal battery
Data Source
AI summary
The present invention generally relates to a thermal battery testing apparatus and a method for testing a thermal battery. The method includes one or more of the following steps: connecting the thermal battery in series with a resistance; connecting the thermal battery and resistance in series with a sinusoidal voltage source; applying a sinusoidal voltage to the thermal battery, measuring an impedance, reactance and/or capacitance across two terminals of the thermal battery, comparing the measured impedance, reactance and/or capacitance to a reference impedance, reactance and/or capacitance; and indicating whether the tested thermal battery is “in family” or “out of family.” The battery testing apparatus may include a testing device configured to apply a sinusoidal voltage to the thermal battery and to measure the impedance, reactance and/or capacitance across two terminals of the thermal battery. The testing apparatus may further be configured to report “out of family” batteries.