Battery Pack Contact Detection via Voltage Difference
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Solution Overview
Problem
High contact resistance between power bars and electrodes in battery packs can lead to power dissipation, reduced battery lifetime, and potential fires or explosions, especially in high-current applications, necessitating effective contact detection methods.
Innovation Solution
A battery pack system with integrated supervisors that measure voltage differences between electrodes and communication wires to detect degraded contacts, such as corrosion or loose connections, using digital circuits and switches to indicate contact degradation without additional external components or wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If contact resistance is reduced to minimize power dissipation, then energy loss is reduced, but contact degradation (corrosion, loosening) becomes harder to detect early
Solution Approach 1:
The supervisor circuit performs preliminary detection of contact resistance using the communication wire before significant degradation occurs. By continuously monitoring the voltage on the communication wire during normal operation, the system can detect early signs of contact degradation (corrosion or loosening) before they lead to excessive power dissipation or safety hazards, enabling preventive maintenance.
Solution Approach 2:
The communication wire serves as an intermediary element that dual-functions: it transmits control signals between the supervisor and battery cells while simultaneously acting as a sensing path for detecting contact resistance. The supervisor measures the voltage on this intermediary wire to infer contact conditions without requiring separate detection wiring, thus resolving the contradiction between minimizing energy loss and ensuring reliable detection.
2Measurement precision
If additional detection components are added to monitor contact resistance, then detection precision is improved, but device complexity increases
Solution Approach 1:
The communication wire is designed to serve multiple functions simultaneously: it acts as both a control signal transmission path and a sensing path for contact resistance detection. The supervisor circuit uses the existing communication infrastructure to measure contact resistance by monitoring voltage levels during communication operations, eliminating the need for separate detection wires or additional external components, thus maintaining measurement precision while minimizing device complexity.
Solution Approach 2:
The communication wire serves itself dual purposes: its primary function of transmitting control signals and its secondary function of enabling contact resistance detection. The system leverages the inherent electrical properties of the communication wire during normal operation to perform self-diagnosis of contact conditions, avoiding the need for dedicated detection infrastructure and reducing overall system complexity.
3Reliability
If contact resistance monitoring is implemented continuously, then reliability is improved, but energy consumption increases
Solution Approach 1:
The supervisor circuit performs contact resistance detection periodically during scheduled communication operations with battery cells rather than continuously. By leveraging the existing periodic communication protocol, the supervisor can measure contact resistance at regular intervals when communication occurs, ensuring reliable monitoring while minimizing energy consumption by avoiding continuous active measurement circuits.
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 early detection of contact degradation, improving battery pack performance, extending battery life, and preventing damage by identifying and addressing issues like corrosion or loose contacts without adding extra components or wiring.
Implementation Method 1
a voltage detector to measure a first voltage between a first electrode and a second electrode of the first battery cell in a first state, and to measure a second voltage between the first electrode of the first battery cell and the communication wire in a second state
Data Source
AI summary
Method and apparatus for contact detection in battery packs are disclosed. A battery pack, comprising: at least a first battery cell and a second battery cell, the first battery cell having a first electrode and a second electrode, and the second battery cell having a third electrode and a fourth electrode; a power bar for coupling the second electrode of the first battery cell to the third electrode of the second battery cell; a communication wire for signal communication between the first battery cell and the second battery cell, wherein the first battery cell comprises a supervisor, which comprises a voltage detector to measure a first voltage between the first electrode and the second electrode of the first battery cell in a first state, and to measure a second voltage between the first electrode of the first battery cell and the communication wire in a second state; and a digital circuit to compute a voltage difference between the first voltage and the second voltage, and to indicate degraded contact of the power bar if the voltage difference is out of a predetermined threshold range. A battery cell and a method for monitoring a battery pack are also disclosed.