Differential Battery Tester Circuit for Rapid Impedance Assessment
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Solution Overview
Problem
Conventional battery testers face challenges in accurately assessing the condition of batteries, particularly in estimating output impedance and state of health, often requiring calibration for non-linear distortions and quiescent voltage estimation, and are inefficient in rapid testing of pairs for manufacturing defects.
Innovation Solution
A differential battery testing circuit and method that compares a battery under test to a reference voltage source using differential voltage measurements, applying synchronized load impedances to estimate output impedance and state of health, thereby avoiding the need for quiescent voltage estimation and mitigating non-linearity issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional battery testers use single-battery testing with calibration, then measurement precision can be achieved, but device complexity and testing time increase
Solution Approach 1:
The testing system is segmented into two independent parallel circuits: one for the battery under test and one for the reference battery. Each circuit has its own switches and load impedances, allowing independent control and measurement. This segmentation eliminates the need for complex calibration by using a known good reference battery instead of calibration procedures.
Solution Approach 2:
A reference battery that replicates the characteristics of a healthy battery is used as a copy for comparison. The reference battery is connected in parallel with the battery under test, and both are subjected to the same loading conditions. The differential voltmeter measures the voltage difference between the two batteries, providing a direct comparison that eliminates calibration needs.
2Productivity
If conventional battery testers perform rapid testing of pairs, then productivity increases, but measurement precision may be compromised
Solution Approach 1:
Two batteries (the battery under test and the reference battery) are merged into a single parallel testing arrangement. Both batteries share common switching elements and load impedances, allowing simultaneous testing. The differential voltmeter measures the voltage difference between the two batteries, enabling rapid paired testing while maintaining measurement precision through differential measurement.
3Device complexity
If quiescent voltage estimation is used in conventional testers, then device complexity is reduced, but measurement precision deteriorates due to non-linearity
Solution Approach 1:
The system uses real-time differential voltage measurement between the battery under test and the reference battery as feedback. The differential voltmeter continuously measures the voltage difference, and the processor uses this feedback to determine battery condition. This feedback mechanism eliminates the need for quiescent voltage estimation and compensates for non-linearity by using the reference battery's known characteristics.
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
Enables accurate and rapid assessment of battery condition, including output impedance and state of health, without the need for complex calibration, and facilitates efficient testing of pairs for manufacturing defects.
Implementation Method 1
a voltmeter configured to measure voltage between a first input node and a second input node
Data Source
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AI summary
Systems and methods for battery testing are described. Some of the methods for battery testing include applying a first load impedance to a battery, applying a second load impedance to a reference voltage source, measuring a voltage between a positive terminal of the battery and a positive terminal of the reference voltage source, wherein a negative terminal of the battery is connected via a conductor to a negative terminal of the reference voltage source, and determining a condition of the battery based on the measured voltage.