Battery Case Bypass Switch for Overcharge Protection
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Solution Overview
Problem
Rechargeable batteries face safety risks due to continuous overcharging, which can lead to increased internal pressure, heat generation, and potential fires or explosions, as existing protection devices may fail or malfunction.
Innovation Solution
A device comprising a series-connected module of unit cells with bypass switches and fuses that physically contact electrode terminals and vary resistance based on internal pressure and temperature, creating a bypass path to prevent overcharging and heat buildup by forming electrical connections and opening fuses when abnormal pressure is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical protection means (fuse) and controller are used to prevent overcharging, then safety from high-voltage short circuit and heat generation is improved, but the device complexity increases and the protection may fail if the controller or fuse defects occur
Solution Approach 1:
The battery package case itself serves as the protection mechanism. When internal pressure exceeds a predetermined level, the case automatically deforms to open the bypass switch, creating a bypass path without requiring external controllers or fuses. This self-service approach eliminates complex protection devices while maintaining safety.
Solution Approach 2:
The invention extracts the protection function from separate components (controller and fuse) and integrates it into the battery package case structure itself. The bypass switch is mechanically coupled to the case, allowing the case to directly control the electrical connection based on its deformation state.
2Speed
If bypass switches are integrated within the unit cells, then the protection response speed is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The bypass switch is merged with the battery package case through mechanical coupling. The case deformation directly actuates the bypass switch, combining the pressure-sensing function and the switching function into a single integrated mechanism that responds immediately to overpressure conditions.
Solution Approach 2:
The battery package case acts as an intermediary between the internal pressure and the bypass switch. The case deformation serves as the mechanical mediator that translates internal pressure into the opening/closing action of the bypass switch, enabling rapid response without complex sensing circuits.
3Measurement precision
If resistance elements with temperature-dependent resistance are used in the bypass switch, then the ability to detect abnormal conditions is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The bypass switch utilizes temperature-dependent resistance changes in its contact elements. As temperature varies, the resistance of the contact elements changes, providing detection capability for abnormal conditions. This parameter change approach enables sensing without complex 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
The device effectively prevents fires caused by continuous overcharging by bypassing the unit cells or battery module, ensuring safety through mechanical transformation and resistance-based electrical connections, thereby delaying overcharging and reducing heat generation.
Implementation Method 1
a first connector on the case, having a same polarity as the first electrode terminal, and configured to be physically transformed according to an internal pressure of the case
Implementation Method 2
a second connector configured to form an electrical connection with the first connector, and having resistance that is configured to vary according to an internal temperature of the case
Data Source
AI summary
Embodiments of the present invention relate to a device for protecting a rechargeable battery including a plurality of unit cells contained in a module case and coupled in series between a first module electrode terminal and a second module electrode terminal, a plurality of bypass switches separated from the plurality of unit cells, electrically connected to each other, and configured to physically contact a first electrode terminal of a respective one of the unit cells according to an internal pressure thereof, and a plurality of bypass fuses for connecting adjacent ones of the plurality of unit cells, and for connecting a last unit cell of the plurality of unit cells and the second module electrode terminal, respectively.