Junction Integrity Test Fixture for Battery Busbars
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Solution Overview
Problem
Existing methods for evaluating the electrical integrity of junctions between electrical lead traces and busbars in battery packs are inadequate, as they fail to detect non-obvious variations in mechanical fastening that can affect electrical conductivity, leading to potential issues over time or under stress.
Innovation Solution
A test fixture is employed that includes an electric power supply, an electric monitoring device, and a mechanical stress-inducing device, which applies mechanical stress to the junction while monitoring the electrical potential, allowing for the evaluation of the junction's integrity based on dynamic changes in resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If static impedance tests and visual inspections are used to evaluate junction electrical integrity, then the evaluation process is simple, but non-obvious variations in mechanical fastening affecting electrical conductivity cannot be detected
Solution Approach 1:
The test fixture applies mechanical stress to the junction before final electrical measurement, simulating operational conditions that reveal potential failures. This preliminary stress application exposes non-obvious variations in mechanical fastening that would not be detected by static tests alone, thereby improving measurement precision without excessive complexity
Solution Approach 2:
The evaluation method transitions from static impedance testing to dynamic testing by applying mechanical stress during measurement. The mechanical stress-inducing device creates dynamic conditions that simulate real-world operational stresses, enabling detection of conductivity variations that only manifest under stress conditions
2Reliability
If mechanical fasteners are used to join electrical lead traces to busbars, then assembly is simplified, but electrical integrity under stress conditions cannot be ensured
Solution Approach 1:
The test fixture performs preliminary stress testing on junctions during the manufacturing process, identifying defective connections before final assembly. This allows manufacturers to reject or rework problematic junctions while the manufacturing process is still accessible, ensuring reliability without requiring complex post-assembly modifications
Solution Approach 2:
The test fixture uses the junction's own electrical properties and mechanical response to stress as the evaluation criteria. By measuring electrical conductivity changes under applied mechanical stress, the system uses the junction's inherent characteristics to self-evaluate its integrity, eliminating the need for external reference standards or complex comparison procedures
3Measurement precision
If dynamic stress testing is applied to evaluate junction integrity, then detection accuracy improves, but test time and complexity increase
Solution Approach 1:
The test fixture applies mechanical stress in periodic cycles rather than continuous loading, allowing for efficient data collection at critical stress points. This periodic application of stress enables the system to capture electrical conductivity changes at key moments in the stress cycle, achieving high detection accuracy without requiring prolonged continuous testing
Solution Approach 2:
The test fixture integrates multiple functions into a single device: mechanical stress application, electrical conductivity measurement, and automated evaluation. By combining these functions in one unified system, the fixture eliminates the need for separate testing equipment and procedures, reducing overall test time while maintaining high detection accuracy
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 approach effectively detects variations in electrical conductivity at the junction, ensuring that the mechanical fastening meets specifications by identifying changes in resistance when mechanical stress is applied, thereby ensuring the reliability of the battery pack connections.
Implementation Method 1
an electric monitoring device disposed to monitor electrical potential across the junction... Electrical integrity of the junction is evaluated based upon the monitored electrical potential across the junction
Implementation Method 2
A mechanical stress-inducing device is disposed to apply mechanical stress proximal to the junction
Data Source
AI summary
A method and a test fixture for evaluating a junction between an electrical lead trace and a busbar are described, and include an electric power supply disposed to supply electric power to the electrical lead trace and an electric monitoring device disposed to monitor electrical potential across the junction. A mechanical stress-inducing device is disposed to apply mechanical stress proximal to the junction. The electric monitoring device monitors the electrical potential across the junction of the electrical lead trace coincident with the mechanical stress-inducing device applying mechanical stress proximal to the junction when the electric power supply is supplying electric power to the electrical lead trace. Electrical integrity of the junction is evaluated based upon the monitored electrical potential across the junction.