Battery Cell Characterization for Pack Assembly Matching
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Solution Overview
Problem
In battery packs, varying charging characteristics among cells can lead to undesired effects such as incomplete charging or over-charging, posing risks like thermal runaway, especially in Li-ion batteries, due to differences in charge rise times.
Innovation Solution
Characterizing battery cells by determining their charge characteristics, such as internal resistance and capacitance, and using an algorithm to classify them based on similarity, ensuring only cells with matching profiles are combined in battery packs to maintain consistent charging and discharging profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If battery cells with varying charging characteristics are combined in a battery pack, then the battery pack can be assembled more quickly and with fewer restrictions, but some cells may not charge to the same level as others, leading to incomplete charging or over-charging risks
Solution Approach 1:
The patent applies preliminary action by characterizing and classifying battery cells before they are assembled into battery packs. Each cell undergoes charge characterization to determine its charge profile, and cells are classified into groups based on similarity. This pre-classification ensures that when cells are assembled into packs, they have matching charging characteristics, preventing over-charging or incomplete charging issues while maintaining efficient assembly processes.
2Reliability
If battery cells are classified and matched by charge characteristics before assembly, then charging safety and reliability are improved, but the characterization and classification process adds time and complexity to the manufacturing process
Solution Approach 1:
The patent applies parameter changes by transforming the complex problem of ensuring cell compatibility into a simplified classification system based on charge profile parameters. Instead of manually comparing multiple cell characteristics, the system characterizes each cell's charge behavior and assigns it to a classification group. This parameter-based approach maintains high reliability while reducing manufacturing complexity by providing an automated, standardized classification process.
3Adaptability or versatility
If cells with different rise times are assembled in a battery pack, then assembly flexibility is increased, but the pack may not achieve designed charge capacity or may be subjected to over-charge
Solution Approach 1:
The patent applies local quality by ensuring that each battery pack contains cells with locally matched characteristics - specifically, cells within the same classification group have similar charge profiles and rise times. This localized matching within packs maintains assembly flexibility across different pack configurations while ensuring precise charge capacity achievement, as each pack is composed of homogeneously characterized cells.
Data Source
AI summary
A system and method for use characterizing battery cells. Charging and/or discharging characteristics for each of a plurality of battery cells may be determined, the battery cells may be marked based on the determined charging and/or discharging characteristics, and grouped based on the marking—e.g., such as battery cells having similar or near similar charging and/or discharging characteristics are grouped together. Battery packs may then be assembled such that each battery pack would comprise only battery cells belonging to the same group (or “in-family”). The charging characterization may be based on voltage rise curve, which may be determined for each battery cell—e.g., based on sampling or recording during charging, at sufficient rate. Battery cells may subsequently be monitored, during use of the battery packs, to ensure that the charging or discharging does not change, and battery cells exhibiting change in characteristics may be manually or automatically removed from use.