Battery Charge Current Testing via Impedance and Temperature
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Solution Overview
Problem
Existing methods for determining the maximum charge current for batteries, especially those with complex structures, are inaccurate due to the impact of reference electrode placement and manufacturing methods, and do not account for temperature variations, affecting safety and service life.
Innovation Solution
A charge current test method that involves charging the battery at a first current until a preset cutoff voltage is reached, stopping when a state-of-charge increment reaches a preset value, and continuing after a set time, calculating impedance to determine the maximum state-of-charge value, considering temperature effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a three-electrode battery with a reference electrode is used to test charge current, then the relationship between current and state of charge can be researched, but the method is only applicable to simply structured laminated batteries with small capacity and the reference electrode placement significantly impacts test results
Solution Approach 1:
The patent extracts and removes the reference electrode from the testing system, transitioning from a three-electrode configuration to a two-electrode configuration. This extraction eliminates the limitations associated with reference electrode placement while maintaining the ability to measure charge current accurately through alternative methods involving voltage monitoring and capacity calculation.
Solution Approach 2:
The patent creates a universal testing method that works across different battery structures (laminated, prismatic, cylindrical) and capacity ranges by replacing the structure-specific reference electrode approach with a generalizable two-electrode method that uses voltage monitoring and capacity-based state of charge calculation.
2Productivity
If charging is performed at high current to reduce charging time, then productivity increases, but the battery safety and service life may be affected due to potential side reactions
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring battery voltage during charging and using this information to calculate state of charge and detect impedance changes. This real-time feedback allows the system to identify the onset of side reactions and adjust charging parameters accordingly, enabling safe high-current charging while preventing safety issues.
Solution Approach 2:
The patent performs preliminary characterization of the battery by conducting tests at different charge currents to establish the relationship between charge current and maximum state of charge. This preliminary action creates a reference dataset that guides subsequent charging operations, allowing the system to operate at optimal high currents while avoiding conditions that would compromise safety.
3Quantity of substance
If the battery is charged until high state of charge to maximize energy storage, then energy capacity increases, but the impedance may decrease indicating side reactions that affect service life
Solution Approach 1:
The patent replaces traditional voltage-threshold-based state of charge determination with an impedance-based detection method. By monitoring changes in battery impedance during charging, the system can accurately identify the maximum state of charge and detect side reactions, providing more precise control over the charging process and improving the accuracy of state of charge determination.
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 accurate determination of the maximum charge current without requiring a special-purpose three-electrode battery, applicable to various aged batteries, and improves test accuracy by accounting for temperature.
Implementation Method 1
charging a to-be-tested battery at a first current under a first temperature
Implementation Method 2
calculating an impedance of the to-be-tested battery during the first preset time length
Data Source
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Figure 2
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AI summary
This application provides a charge current test method and device, and a charge test system. The method includes: charging a to-be-tested battery at a first current under a first temperature until a voltage of the to-be-tested battery reaches a preset cutoff voltage, stopping charging whenever an increment of a state-of-charge value of the to-be-tested battery reaches a preset value during the charging of the to-be-tested battery, and continuing to charge after a duration of stopping charging reaches a first preset time length; calculating an impedance of the to-be-tested battery during the first preset time length; and determining, based on the impedance, a maximum state-of-charge value that is allowed to be reached when the charging is performed at the first current under the first temperature. Compared with the prior art, the foregoing solution enables direct test of most commercial batteries on the market without a need to manufacture a special-purpose three-electrode battery. In addition, the solution takes temperature into account, thereby improving accuracy of test results.