Battery Internal Resistance Measurement via Voltage Slope Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional internal resistance measuring circuits for batteries face challenges such as inaccurate measurements due to Helmholtz capacitance effects, excessive battery discharge time for precise voltage readings, and inability to handle varying battery types, leading to incorrect resistance readings or battery damage.
Innovation Solution
A battery internal resistance measuring device and method that utilizes a voltage detecting unit, measurement resistors, a switch, and a measurement controller with a differential value calculating unit to identify discharge starting and ending points from voltage signal waveforms, allowing for accurate calculation of open-circuit and short-circuit voltages and internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the discharging time is prolonged to obtain stable voltage readings, then the measurement precision is improved, but the battery energy consumption increases excessively
Solution Approach 1:
The patent applies preliminary action by pre-calculating the differential values (slopes) of voltage sampling points during the discharge process. Instead of waiting for the voltage to naturally stabilize after discharge, the system proactively identifies the discharge starting and ending points by detecting when the differential values meet specific criteria (first differential value ≤ first threshold and second differential value ≥ second threshold). This allows the system to determine open-circuit and short-circuit voltages at optimal moments without requiring prolonged discharge times, thereby improving measurement precision while minimizing battery energy consumption.
2Device complexity
If the Helmholtz capacitance effect is ignored to simplify measurement, then the device complexity is reduced, but the measurement precision deteriorates
Solution Approach 1:
The patent introduces an intermediary approach by using differential value calculation as a mathematical mediator to handle the Helmholtz capacitance effect. Rather than adding complex hardware circuits to compensate for capacitance, the system calculates the differential values (slopes) between adjacent voltage sampling points and uses these to identify precise discharge boundaries. The method determines open-circuit voltage at the discharge starting point and short-circuit voltage at the discharge ending point by detecting when differential values cross specific thresholds, thereby achieving accurate internal resistance measurement while maintaining simple circuit architecture.
3Ease of operation
If a fixed measurement current is used to simplify the measurement process, then the ease of operation is improved, but the adaptability to different battery types deteriorates
Solution Approach 1:
The patent applies dynamics by making the measurement process adaptive rather than fixed. The system dynamically determines discharge starting and ending points based on real-time differential value calculations, allowing it to automatically adjust to different battery characteristics. By continuously monitoring the slope of voltage changes and identifying when differential values meet specific criteria, the method can accommodate various battery types, capacities, and discharge rates without requiring manual configuration or fixed measurement parameters, thus achieving both ease of operation and high adaptability.
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 approach enables precise measurement of internal resistance without excessive battery discharge, suitable for various battery types, reducing measurement errors and preventing battery damage.
Implementation Method 1
voltage-dependent Helmholtz capacitance is produced during the discharge of the battery 2' and causes the real waveform of the output voltage signal become an incomplete square waveform
Data Source
AI summary
The present invention discloses a battery internal resistance measuring device and a method thereof, wherein the battery internal resistance measuring device comprises a voltage detecting unit, at least one measurement resistor, at least one switch, and a measurement controller. By means of further explanation, the measurement controller at least comprises a differential value calculating unit for treating a differential value calculation or a slope calculation to each two of adjacent voltage sampling values on a waveform of a discharge voltage signal of the battery, such that the measurement controller can subsequently find out a discharge starting point and a discharge ending point according to data of the differential value calculations or the slope calculations. Eventually, the measurement controller calculates an internal resistance of the battery after picking up an open-circuit voltage and a short-circuit voltage from the discharge starting point and the discharge ending point.