Electric Power Storage Device Inspection via Reverse Current Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining the quality of electric power storage devices are time-consuming and inaccurate due to variations in contact resistance and measurement conditions, particularly when measuring voltage, which affects the reliability of self-discharge assessments.
Innovation Solution
An inspection method that measures current instead of voltage, where an external power supply is connected to a charged electric power storage device in reverse voltage direction, adjusting the voltage to prevent initial current flow, and then acquiring a converged current value to assess the device's quality, with grouping based on initial voltage and manufacturing lot to reduce variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage measurement is performed to determine self-discharge amount, then quality determination can be made, but measurement time is prolonged and accuracy is reduced due to contact resistance variations
Solution Approach 1:
The patent replaces voltage measurement with current measurement to eliminate the influence of contact resistance. By measuring the current flowing through the battery during a controlled discharge period and calculating self-discharge amount from the current integral, the method avoids the mechanical connection issues inherent in voltage measurement, thereby improving both measurement speed and accuracy simultaneously
2Reliability
If leaving time is extended to ensure accurate voltage-based quality determination, then measurement accuracy improves, but processing time increases significantly
Solution Approach 1:
The patent changes the measurement parameter from voltage to current, and introduces a controlled discharge process with specific current thresholds. By discharging the battery at a controlled rate and measuring the current over a shortened time period, then calculating the self-discharge amount from the current integral, the method achieves reliable quality determination without requiring extended leaving time, thus maintaining reliability while improving productivity
3Measurement precision
If current measurement is used instead of voltage measurement, then measurement time is reduced and accuracy is improved, but measurement results become dependent on charging voltage and environmental conditions
Solution Approach 1:
The patent incorporates feedback mechanisms by continuously monitoring the discharge current and comparing it against predetermined thresholds. The measurement process adjusts based on the observed current behavior, and the self-discharge calculation accounts for the actual discharge conditions. This feedback approach enables the method to compensate for variations in charging voltage and environmental conditions, making the current measurement approach as adaptable as traditional voltage measurement
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 significantly reduces processing time and improves accuracy by using current measurement, allowing for prompt and reliable quality determination of electric power storage devices, independent of measurement conditions.
Implementation Method 1
connecting an external electric power supply to a charged electric power storage device in an reverse voltage direction to form a circuit
Data Source
AI summary
An external electric power supply is connected to a charged electric power storage device in a reverse voltage direction to form a circuit. A voltage of the external electric power supply is adjusted such that a current does not flow immediately after the connection. Then, current measuring of acquiring a converged current value of the current in the circuit due to a decrease in the voltage of the electric power storage device, and quality deciding based on the converged current value are performed. Before the quality deciding, the electric power storage device is grouped such that the converged current value of when the electric power storage device is a normal product is constant in a group. In the quality deciding, a degree of variation in the converged current value is calculated for each group, and the quality is determined by comparing the calculated degree of variation with its predetermined level.