Lead-Acid Battery Capacity Estimation via Voltage and Resistance Segmentation
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Solution Overview
Problem
Existing secondary battery management systems inaccurately estimate battery capacity due to reliance on internal resistance values alone, leading to erroneous charging determinations and inadequate measures for deteriorating batteries.
Innovation Solution
An energy storage system with a battery management unit that defines capacity changes based on open voltage and internal resistance, distinguishing between correlated and non-correlated deterioration factors to accurately estimate battery capacity, including sulfation and grid corrosion in lead-acid batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If battery capacity is estimated based only on internal resistance value, then the estimation process is simple, but the estimation accuracy is insufficient
Solution Approach 1:
The invention segments the deterioration factors into two distinct categories: those correlated with open voltage (e.g., sulfation) and those not correlated with open voltage (e.g., grid corrosion). By separating the estimation of capacity changes into these two categories, the system achieves more accurate battery capacity estimation while maintaining a manageable level of complexity through modular processing steps.
2Loss of information
If display pattern is used to show remaining battery level, then user can easily grasp battery status, but accurate charging determination becomes difficult when battery deteriorates
Solution Approach 1:
The invention introduces a feedback mechanism where the notification unit provides information about both the remaining battery level and the battery capacity deterioration state. This additional feedback loop allows users to make more accurate charging decisions by understanding not just how much charge remains, but also how the battery's overall capacity has degraded, thereby resolving the information accuracy problem while maintaining ease of operation.
Data Source
AI summary
An energy storage system includes a lead-acid battery, a battery management unit. The battery management unit defines, based on an open voltage of the lead-acid battery, a first amount of change in a capacity of the lead-acid battery from a reference state, correlating with the open voltage of the lead-acid battery and caused by a first deterioration factor and defines, based on the first amount of change in the capacity and an amount of change in overall internal resistance of the lead-acid battery from the reference state, a second amount of change in a capacity of the lead-acid battery, not correlating with the open voltage and caused by a second deterioration factor. The battery management unit defines, based on the first and second amounts of change in the capacity, at least one of a battery capacity of the lead-acid battery or an amount of change in the battery capacity from the reference state.