# 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

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._