Battery Cell Voltage Logging for Short Circuit Detection
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Solution Overview
Problem
Rechargeable batteries, particularly lithium-ion batteries, face safety risks due to undetected short circuits, which can lead to thermal runaway and other hazardous conditions, as existing battery management systems fail to differentiate between normal self-discharge and developing internal shorts.
Innovation Solution
A battery management unit that monitors and logs voltages of cell blocks before shutdown, compares them upon restart, and takes protective action if significant voltage drops are detected, indicating a potential short circuit, to prevent further charging or discharging of affected cells and alert the system to potential hazards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the battery management unit provides additional charge to cell blocks with lower charge levels to equalize charge across the battery pack, then the electrical capacity of each cell block is maximized, but weak cells with developing internal shorts may be overcharged beyond safe limits, risking thermal runaway
Solution Approach 1:
The system performs preliminary detection of internal shorts by comparing voltage drops during idle periods before charging operations. By identifying weak cells in advance through voltage comparison between active and idle states, the system can prevent overcharging dangerous cells while still maximizing the capacity of healthy cells through selective charge management.
2Reliability
If the battery management system continuously monitors cell voltages to detect internal shorts, then safety is improved, but the complexity of the monitoring and detection system increases
Solution Approach 1:
The system uses the battery pack's own operational characteristics (voltage changes during charging and idle periods) to detect internal shorts. By comparing voltage drops during idle states against expected values, the system performs self-diagnosis without requiring external test equipment or complex additional monitoring hardware, thus maintaining safety while minimizing added complexity.
3Stability of the object's composition
If the battery management unit actively balances charge by pumping charge from one cell block to another, then charge equalization is achieved, but weak cells with internal shorts may be further compromised by additional charge cycling
Solution Approach 1:
The system applies different charge management strategies to different cell blocks based on their individual health status. By identifying weak cells with internal shorts through voltage comparison, the system can apply restricted or modified charging protocols to affected cells while maintaining normal charge balancing operations for healthy cells, thus preserving overall charge equalization without compromising weak cell integrity.
Data Source
AI summary
A method and apparatus for short circuit detection for batteries. Some embodiments of a method include receiving a battery pack in a system, where the battery pack is rechargeable and includes multiple battery cell blocks, each cell block including one or more battery cells. The voltages of the plurality of cell blocks are monitored. Upon shutting down the system, the voltages of the plurality of cell blocks are logged to generate a set of logged voltage values. Upon restarting the system, the current voltage values of the cell blocks are measured. A determination whether any of the battery cells of the battery pack has developed a short circuit is made based at least in part on a comparison of the current voltage values with the set of the logged voltage values.