Dynamic Delta Voltage Measurement for Battery Pack Testing
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Solution Overview
Problem
Current methods for testing battery pack welds and cell integrity are inadequate in identifying issues, leading to potential problems such as imbalance, temperature rises, and capacity loss due to improper welding or cell charging/discharging rates, often resulting in scrapping of modules.
Innovation Solution
A method involving measuring cell open voltage and voltage under charge or load at predetermined intervals to calculate dynamic delta voltage, which helps identify weld and cell failures by determining differences exceeding predetermined levels, allowing for quick detection of issues like weld durability and lot-to-lot variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional voltage measurement methods are used to test battery welds and cell integrity, then the testing process is simple to implement, but the ability to identify weld and cell failures is insufficient
Solution Approach 1:
The patent changes the measurement parameters from static voltage alone to dynamic voltage differences (delta voltage) measured at multiple time points during charge/discharge cycles. This transformation enables detection of weld and cell failures that static measurements cannot identify, directly resolving the contradiction between detection capability and measurement simplicity.
Solution Approach 2:
The patent transitions from static voltage measurement to dynamic voltage measurement by capturing voltage at multiple time points (t1, t2, t3) during active charge/discharge cycles. This dynamic approach reveals transient failures and impedance issues that static measurements miss, improving detection capability while maintaining practical implementation through standardized timing protocols.
2Measurement precision
If comprehensive battery testing is performed to identify all weld and cell issues, then detection accuracy improves, but test cycle time increases
Solution Approach 1:
The patent employs periodic voltage measurements at specifically timed intervals (t1, t2, t3) during charge/discharge cycles rather than continuous monitoring. This periodic sampling approach captures critical transient events while minimizing measurement overhead, achieving high detection accuracy without excessive test duration.
Solution Approach 2:
The patent performs voltage measurements at predetermined time points that are optimized to detect failures before they propagate. By measuring at t1 (initial), t2 (intermediate), and t3 (final) points, the system identifies weld and cell issues early in the test cycle, enabling quick rejection of defective units without requiring extended testing periods.
3Productivity
If static voltage range measurement is used, then the testing process is quick, but it cannot conclusively identify weld or cell problems
Solution Approach 1:
The patent transforms the measurement parameter from static voltage range to dynamic delta voltage (difference between voltage at t1 and voltage at t2/t3). This parameter change enables the test to maintain quick execution while achieving conclusive diagnostic capability, as the voltage change over time reveals impedance and connection issues that static measurements cannot detect.
Solution Approach 2:
The patent uses the measured delta voltage values as feedback to determine pass/fail status and guide further testing or rejection decisions. By comparing measured voltage differences against predetermined thresholds, the system quickly identifies defective welds and cells with high reliability, maintaining fast testing throughput while ensuring accurate defect detection.
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 reduces manufacturing test cycle time, identifies potential weld and cell quality issues promptly, and enables correction before product release, thereby reducing pack failures in use by providing a fast and effective evaluation of battery pack conditions.
Implementation Method 1
measuring a voltage under charge, or a voltage under load, or both, at a predetermined time interval for each battery cell group
Data Source
AI summary
A method of evaluating battery packs is described. The method includes measuring a cell open voltage for each battery cell group in a section of battery cells; measuring a voltage under charge, or a voltage under load, or both, at a predetermined time interval for each battery cell group in the section of battery cells; determining the magnitude of the difference between the open cell voltage and the voltage under charge, or the voltage under load, or both, for each battery cell group in the section of battery cells by subtracting the voltage under charge from the cell open voltage, or subtracting the voltage under load from the cell open voltage, or both; and determining if the magnitude of the difference between the open cell voltage and the voltage under charge, or the voltage under load, or both, for each battery cell group in the section of battery cells exceeds a predetermined level.