Secondary Battery Self-Discharge Current Testing for Low-Voltage Prediction

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Solution Overview

Problem

Current methods fail to accurately predict low voltage battery possibilities in secondary batteries due to variations in self-discharge rates, leading to potential degradation in battery module performance and life.

Innovation Solution

An apparatus and method that measure the intensity of self-discharge current in secondary batteries using a test path, sensor unit, constant voltage generation unit, and control unit to determine the level of self-discharge and identify faulty batteries within a battery module by analyzing discharge current profiles and cumulative capacity graphs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If self-discharge rate is used to predict low voltage battery possibility, then battery performance prediction is attempted, but measurement precision is insufficient due to variations in self-discharge rates

Engineering Contradiction:
Improveprediction accuracy of low voltage battery possibilityVSAvoidconsistency of self-discharge rate
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent changes the measurement parameter from simple self-discharge rate to self-discharge current intensity, which provides more precise and reliable data for predicting low voltage battery possibilities. This parameter transformation enables accurate differentiation between normal and abnormal self-discharge behaviors.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces traditional voltage-based prediction methods with a current-based measurement system using sensor units and test paths. This substitution of measurement approach enhances precision by directly measuring electrical current characteristics rather than inferring from voltage changes.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Difficulty of detecting and measuring

If traditional testing methods are used, then testing process is simple, but detection capability for faulty batteries is insufficient

Engineering Contradiction:
Improvedetection capability of faulty batteriesVSAvoidcomplexity of testing apparatus
Core Design Contradiction:
Difficulty of detecting and measuringVSDevice complexity

Solution Approach 1:

The patent segments the testing system into distinct functional modules: test paths for individual battery cells, sensor units for current measurement, constant voltage generation units for controlled testing, and control units for data analysis. This segmentation enables sophisticated detection capabilities while maintaining modular simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces intermediary components including sensor units that mediate between the battery and measurement system, and control units that mediate between multiple batteries in a battery module. These intermediaries enable accurate detection of faulty batteries without requiring direct complex interactions between all battery components.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If battery module performance is maintained, then overall system reliability is preserved, but individual faulty batteries cannot be identified and isolated

Engineering Contradiction:
Improvebattery module performanceVSAvoidinformation about faulty battery location
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent implements feedback mechanisms where control units receive measurement data from sensor units, analyze self-discharge current characteristics, and generate identification information about faulty batteries. This feedback loop enables continuous monitoring and precise identification of problematic batteries while maintaining overall module reliability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent performs preliminary testing of individual battery cells within the module using dedicated test paths and sensor units before full module operation. This preliminary action identifies faulty batteries in advance, allowing for their isolation and replacement before they compromise overall module performance.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3678256B1Apparatus and method for testing secondary battery
Publication Date: 2023.08.30 LG ENERGY SOLUTION LTD
  • EP3678256B1 patent drawingFigure 1
  • EP3678256B1 patent drawingFigure 2
  • EP3678256B1 patent drawingFigure 3

AI summary

Provided is an apparatus and method for testing a secondary battery. The apparatus includes a test path, test terminals provided at two ends of the test path and electrically connected to a positive terminal and a negative terminal of the secondary battery respectively, a sensor unit provided on the test path and configured to measure a discharge current of the secondary battery, a constant voltage generation unit provided on the test path and configured to maintain a constant voltage between the secondary battery and the sensor unit, and a control unit configured to receive data indicating the discharge current from the sensor unit, measure an inflection point on a profile of the discharge current, measure an intensity of the discharge current on the basis of the inflection point, and test a level of self-discharge of the secondary battery based on the intensity of the discharge current.