External Battery Protection Transistor for Lithium-Ion Safety
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Solution Overview
Problem
Lithium-ion battery packs face challenges due to the need for extensive protection circuitry that increases cost, weight, size, and complexity, while also posing safety risks such as thermal runaway and fire, particularly due to the use of protection ICs and FETs within the battery pack.
Innovation Solution
Implementing a battery protection system that uses a battery transistor configured in series outside the battery pack to manage charging and discharging, eliminating the need for protection ICs and FETs within the pack, and utilizing a pass device and transistors to handle fault conditions, thereby reducing weight, size, and cost while maintaining safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protection ICs and FETs are included within the battery pack, then safety is improved, but weight, size, and cost increase
Solution Approach 1:
The patent extracts the protection circuitry (protection IC and FETs) from the battery pack assembly and relocates it to the external system. This removal eliminates the weight, volume, and cost of these protection components from the battery pack while maintaining safety functions through the externally located protection circuitry.
2Reliability
If protection ICs and FETs are included within the battery pack, then safety is improved, but device complexity increases
Solution Approach 1:
The protection circuitry is extracted from the battery pack and placed externally in the system. This extraction simplifies the battery pack structure by removing complex electronic protection components, while the protection functions are maintained in the external system where they can share common protection architecture across multiple batteries.
3Reliability
If protection ICs and FETs are included within the battery pack, then safety is improved, but cost increases
Solution Approach 1:
The protection circuitry components (protection IC and FETs) are removed from the battery pack and relocated to the external system. This extraction eliminates the cost of these components from the battery pack bill of materials and reduces assembly complexity, while safety protection functions are maintained through the externally located protection circuitry that can serve multiple battery cells.
Data Source
AI summary
Embodiments of the systems and methods of direct cell attachment for battery cells disclosed herein operate without the protection FETs and the protection IC, thereby enabling the direct attachment of battery cells to the system without compromising safety. A charger IC comprises a switching regulator whose output is used to charge the battery through a pass device. In example embodiments of the disclosed systems and methods of direct cell attachment, a combination of switching FETs and the pass device are used as a protection device instead of the charge and discharge FETs. During normal operation, the pass device may be used to charge the battery using the traditional battery charging profile. Under fault condition, the switching FETs and pass device may be driven appropriately to protect the system.