How a Battery Automatically Disconnects Itself During Overheating
A safety system for battery packs that uses a heat-sensitive material to physically break the electrical connection between cells if they get too hot, preventing thermal runaway.
Original patent title: “Disconnection device comprising a heat activatable element”
A safety system for battery packs that uses a heat-sensitive material to physically break the electrical connection between cells if they get too hot, preventing thermal runaway. Granted to SAFT Societe des Accumulateurs Fixes et de Traction SA in 2025 with 16 claims.
Key facts
Coverage
What does this patent actually cover?
This patent describes a mechanical safety device integrated into battery packs to prevent catastrophic failure. When a battery cell overheats, a heat-activatable element—such as a shape-memory alloy or bimetal—reaches a specific temperature threshold and deforms. This deformation physically forces a disconnection between the cell's terminal and the connecting part that links it to other cells. Crucially, the heat-sensitive part does not carry electricity during normal operation, meaning it only acts as a passive safety trigger. The system also includes a low-thermal-conductivity material between cells to ensure heat from one failing cell does not immediately trigger the disconnection of its neighbors.
The gap
What does this patent NOT cover?
- Does not cover electronic fuses or circuit breakers that rely on current-sensing logic.
- Does not cover chemical additives or electrolytes designed to suppress fire within the cell.
- Does not cover disconnection methods that rely on melting a conductive link (fuses) rather than mechanical deformation.
- Does not cover systems where the heat-sensitive element itself is part of the electrical current path.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The system separates the safety trigger from the electrical path. Because the heat-activatable element is not part of the current-carrying circuit, it can be optimized purely for its mechanical and thermal properties without worrying about electrical resistance or power loss.
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
High-capacity lithium-ion battery modules for electric vehicles
Large-scale stationary energy storage systems
Industrial battery packs for aerospace applications
Why it matters
The bigger picture
Thermal runaway in large battery packs, such as those in electric vehicles or grid storage, is a major safety risk. By providing a purely mechanical, non-electronic way to isolate a failing cell, this design offers a fail-safe that works even if the battery management system (BMS) software fails or the control circuitry is destroyed by the heat.
Filed
November 30, 2020
Granted
April 29, 2025
Market context
Who's building on this
Companies in this space
SAFT, a subsidiary of TotalEnergies, is a major player in high-reliability battery systems for aerospace and defense. They are actively refining these mechanical safety architectures to meet the rigorous safety standards required for electric aviation and critical infrastructure.
Market impact
This technology addresses the critical 'propagation' problem in battery packs, where one cell's failure causes a chain reaction. By enabling a physical 'air gap' between cells triggered by heat, it provides a robust safety layer that helps manufacturers meet increasingly strict fire safety regulations for high-energy-density battery packs.
Claim 1 — Plain English
What this patent covers
This patent describes a mechanical safety device integrated into battery packs to prevent catastrophic failure. When a battery cell overheats, a heat-activatable element—such as a shape-memory alloy or bimetal—reaches a specific temperature threshold and deforms. This deformation physically forces a disconnection between the cell's terminal and the connecting part that links it to other cells. Crucially, the heat-sensitive part does not carry electricity during normal operation, meaning it only acts as a passive safety trigger. The system also includes a low-thermal-conductivity material between cells to ensure heat from one failing cell does not immediately trigger the disconnection of its neighbors.
The clever bit
The system separates the safety trigger from the electrical path. Because the heat-activatable element is not part of the current-carrying circuit, it can be optimized purely for its mechanical and thermal properties without worrying about electrical resistance or power loss.
What it does not cover
- Does not cover electronic fuses or circuit breakers that rely on current-sensing logic.
- Does not cover chemical additives or electrolytes designed to suppress fire within the cell.
- Does not cover disconnection methods that rely on melting a conductive link (fuses) rather than mechanical deformation.
- Does not cover systems where the heat-sensitive element itself is part of the electrical current path.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
PatentBrief Score
Impact Score
Early stage
Citation count
0/40
No citations yet
Claim breadth
11/20
Broad claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
20/20
Granted within 5 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$33K – $105K
Midpoint $66K · 14.5 yr remaining · industry ×1.4
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
16 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Garitte, E., Borel, P., Dendary, M., NGUYEN, D. A., & GUENNE, L. L. (2025). How a Battery Automatically Disconnects Itself During Overheating (U.S. Patent No. 12,288,901). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/12288901/draco-thrusters
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How a Battery Automatically Disconnects Itself During Overheating cover?
A safety system for battery packs that uses a heat-sensitive material to physically break the electrical connection between cells if they get too hot, preventing thermal runaway.
Who owns patent US 12288901?
SAFT Societe des Accumulateurs Fixes et de Traction SA owns this patent, granted in 2025.
When does this patent expire?
This patent is expected to expire on April 29, 2045, when the invention enters the public domain.
What problem does this patent solve?
Thermal runaway in large battery packs, such as those in electric vehicles or grid storage, is a major safety risk. By providing a purely mechanical, non-electronic way to isolate a failing cell, this design offers a fail-safe that works even if the battery management system (BMS) software fails or the control circuitry is destroyed by the heat.
What does this patent NOT cover?
Does not cover electronic fuses or circuit breakers that rely on current-sensing logic.
Patent monitoring