# 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. - **Patent:** US 12288901 - **Original title:** Disconnection device comprising a heat activatable element - **Owner:** SAFT Societe des Accumulateurs Fixes et de Traction SA - **Granted:** 2025 - **Status:** Active - **Times cited:** 0 - **Field:** energy, mechanical, automotive, aerospace ## What it does 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. ## 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. ## 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. ## Real-world examples 1. High-capacity lithium-ion battery modules for electric vehicles 2. Large-scale stationary energy storage systems 3. Industrial battery packs for aerospace applications ## Why it matters 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. ## 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. **Full plain-English explainer:** https://patentbrief.org/patent/us/12288901/draco-thrusters **Original patent:** https://patents.google.com/patent/US12288901 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Car Battery Modules Combine High and Low Voltage Systems](https://patentbrief.org/patent/us/6828755/battery-system-module) — A self-contained battery module that houses both high and low voltage batteries, a power converter, and safety switches in a single unit designed for efficient heat management. - [How a Hybrid Layer Stops Metal Growths in Lithium Batteries](https://patentbrief.org/patent/us/10566652/lithium-metal-battery-with-hybrid-electrolyte-system) — This patent describes a special multi-layered electrolyte system for lithium metal batteries that uses a stiff, hybrid material to block dangerous metal growths, aiming for safer, higher-energy batteries. - [Making Solid-State Battery Electrodes That Don't Swell and Crack](https://patentbrief.org/patent/us/11239459/low-expansion-composite-electrodes-for-all-solid-state-batteries) — This patent describes a special design for solid-state battery electrodes that uses tiny internal holes and spaces between particles to prevent them from expanding and cracking during charging and discharging. - [Improving Lithium Battery Life with a Built-in Lithium Source](https://patentbrief.org/patent/us/10593988/electrochemical-cell-for-lithium-based-batteries) — This patent describes a method for building rechargeable lithium-based batteries with a special extra lithium source electrode inside that helps the main battery parts work better and last longer by giving them an initial charge of lithium ions. - [How to Build Solid-State Batteries with Tiny Holes for Better Electrolyte](https://patentbrief.org/patent/us/11942620/solid-state-battery-with-uniformly-distributed-electrolyte-and-methods-of-fabric) — This patent describes a method for manufacturing solid-state batteries by punching small holes through battery electrodes and then filling these holes with a liquid that hardens into a solid electrolyte, aiming for more efficient power delivery.