Battery thermal events in electric vehicles begin with subtle chemical changes that produce trace gases well before temperature increases become detectable. Current data shows that early-stage cell degradation can release diagnostic gases like CO, CO2, and H2 at concentrations as low as 10-100 ppm, providing a critical window for intervention before thermal runaway occurs.

The engineering challenge centers on developing sensing systems that can reliably detect and differentiate between normal off-gassing during operation and the specific gas signatures that indicate impending cell failure—all while operating in the demanding automotive environment.

This page brings together solutions from recent research—including selective gas sensor arrays, aspiration-based multipoint monitoring systems, impedance-based diagnostic methods, and active thermal control mechanisms. These and other approaches focus on early detection and automated response to prevent cascade failures in EV battery packs.

1. Device with Annular Flow Path and Inner-Outer Electrode Configuration for Measuring Fluid Aeration via Electrical Properties

SOUTHWEST RESEARCH INSTITUTE, 2025

A device and method for measuring fluid aeration in applications like electric vehicle fluids by evaluating electrical properties like conductivity or capacitance. The device has inner and outer electrodes enclosing an annular flow path between them. The electrode sizes and flow control ensure consistent fluid velocity and cross-sectional area through the annular path. This allows accurate measurement of electrical properties to determine aeration levels.

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2. Battery Leakage Inspection System with Sealing Box and Switchable Component Connectivity

WUXI LEAD INTELLIGENT EQUIPMENT CO LTD, 2025

A leakage inspection system for batteries with high efficiency and reduced reset time. The system uses a sealing box to contain the battery during inspection. Multiple inspecting components, like detectors, are connected to the box. They can be switched between communication with the box cavity, inspecting mode, and disconnected mode. This allows the components to be quickly swapped out between inspections without waiting for residual gas to dissipate. The box can also be moved between sealing and inspection positions using a rack and lift mechanism. This enables efficient workflow by avoiding long reset times.

3. Battery Module with Fluid Conductivity Sensor for Early Thermal Runaway Detection

PLASTIC OMNIUM CLEAN ENERGY SYSTEMS RESEARCH, 2025

Battery module for a vehicle that can detect thermal runaway early to prevent spread and fires. The battery module has a fluid monitoring device inside the housing to detect pollution fluids escaping from cells. It uses an electrical conductivity sensor to measure changes in the fluid conductivity caused by escaped cell fluids. If conductivity spikes, it indicates a cell failure and triggers selective thermal regulation to isolate and prevent spread. This allows diagnosing cell failures early without temperature sensors on each cell.

4. Battery Housing Pressure Monitoring System for Early Detection of Thermal Runaway in Electric Vehicle Cells

VITESCO TECHNOLOGIES GMBH, 2025

Early detection of battery cell thermal runaway in electric vehicle traction batteries to prevent fires and explosions. The method involves monitoring the internal pressure of the battery housing using a pressure sensor. Thermal runaway in the cells generates gas, causing pressure to rise. By continuously monitoring pressure and comparing against thresholds, runaway can be detected early before excessive gas generation. This allows proactive intervention to prevent catastrophic failure.

5. Gas Detection System with Sliding Die and Chamber for Identifying Battery Module Cell Case Defects

LG ENERGY SOLUTION LTD, 2025

Gas detection system for accurately and rapidly identifying damaged cells in battery modules to enable sorting during manufacturing. The system uses a sliding die to move the module into a chamber with multiple gas sensors below it. Circulating gas is purged and then detected by the sensors. This allows locating cells with damaged cases that leak gases. The sliding die and chamber movement allows accessing the module bottom where cracks are more likely. The system enables sorting cells with case defects before module assembly completion.

6. Electrochemical Cell with Vitreous Carbon Electrodes and Gas Analysis Capability for High-Temperature Solid-State Battery Testing

COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES, 2025

Electrochemical cell for testing solid-state batteries at high temperatures with simultaneous measurement of generated gases. The cell has two vitreous carbon electrodes in a ceramic or PEEK cell body with inlet/outlet for carrier gas. It allows testing solid-state batteries while capturing and analyzing gases generated during cycling. The cell body prevents adsorption/corrosion of gases by using non-conductive ceramic or PEEK. The electrodes are fixed to protuberances that move together to apply pressure. This allows testing high pressure solid-state batteries while containing gases.

7. Battery Thermal Runaway Detection System with Multi-Sensor Monitoring and Selective Activation Mechanism

TDK Corporation, 2025

Early detection and response system for battery thermal runaway to mitigate risks and protect against battery fires in electric vehicles. The system uses multiple sensors in the battery packs and modules to monitor properties like strain, hydrogen gas, pressure, temperature, CO/CO2, and current. An algorithm analyzes the sensor data to detect abnormalities indicating potential thermal runaway. If a risk is detected, high-power sensors like gas sensors are selectively activated to confirm. If elevated gas levels are found, remedial actions like battery disabling are taken before thermal runaway occurs. The system provides earlier and more accurate detection compared to conventional methods.

8. Battery Pack Monitoring System with Piezoelectric Sensors for Detecting Thermal Runaway via Dimensional Changes

SAMSUNG SDI CO., LTD., 2025

Battery pack monitoring system for electric vehicles that can detect thermal runaway in individual cells and initiate safety measures when needed. The system uses piezoelectric sensors attached to the battery pack housing to detect dimensional changes due to internal cell pressure increases. Excessive deformation indicates cell degassing and potential runaway. The sensors are located on opposite sides and outside surfaces of the housing to detect pressure-induced expansion. By monitoring housing deformation over time, runaway can be detected before cell rupture. This allows targeted cell shutdowns and cooling to prevent propagation.

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9. Battery Gas Atmosphere Thermal Conductivity Sensor for Early Detection of Thermal Runaway Events

Infineon Technologies AG, 2025

Early detection of thermal runaway events in batteries, like those used in electric vehicles, by detecting the initial venting of gases during the runaway process. A sensor measures the thermal conductivity of the gas atmosphere inside the battery. Changes in conductivity due to venting can be detected as an indicator of an impending thermal runaway. An apparatus with interface and processing circuitry receives the conductivity measurement and determines if venting has occurred. This allows early warning of potential thermal runaway events to mitigate safety risks.

10. Acoustic Sensor-Based System for Detecting Thermal Runaway in Battery Cells Through Infrasound Analysis

VOLVO TRUCK CORPORATION, 2025

Early warning system to detect thermal runaway in electric vehicle batteries using acoustic sensors. The system monitors sound waves emitted from battery cells to predict thermal runaway before it escalates. Acoustic sensors detect low frequency infrasound generated by gas bubbles forming during early stages of thermal runaway. An algorithm analyzes the acoustic data to predict thermal runaway. This allows earlier intervention to prevent escalation compared to temperature sensors.

11. Battery Pack Degassing Unit with Gas Sensor and Processor for Thermal Runaway Prediction

MANN+HUMMEL Ventures Pte. Ltd., 2024

Alert system for predicting battery thermal runaway in electric vehicle packs, using a gas sensor in a degassing unit attached to the battery housing. The sensor detects gas properties like CO2 concentration inside the battery. A processor analyzes the sensor data to estimate the probability of future thermal runaway. The degassing unit has a semipermeable membrane allowing gas exchange but preventing liquid/solid leakage. This isolates the battery interior from external conditions.

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12. Battery Pack Fire Suppression System with Gas and Infrared Detection Mechanism

Kidde Technologies Inc., 2024

Fire suppression system for battery packs in vehicles that detects and responds to cell failure gases and fire conditions. The system uses detectors inside battery packs to sense leaked gases like hydrogen and carbon monoxide, as well as infrared radiation. When certain concentration thresholds are reached, an alarm is triggered and a fire suppressant is released into the battery pack. This cools the cells and prevents thermal runaway. The system also dispatches an alarm to the vehicle operator.

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13. Battery Pack Fire Suppression System with External Gas and Infrared Detection

Kidde Technologies Inc., 2024

Fire suppression system for battery packs to prevent and extinguish fires in electric vehicle batteries. The system uses external gas detectors to monitor battery cell gases like hydrogen and carbon monoxide, as well as infrared radiation. When detectors sense elevated gas levels or infrared, a controller triggers an emergency fire suppression system to release a cooling agent into the battery packs to smother flames. This prevents runaway cell fires from spreading. The external gas detection allows early intervention before internal sensors are affected.

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14. Gas Monitoring System with Selective Sensor Activation for Electric Vehicle Batteries

AUDI AG, 2024

Energy-efficient gas monitoring for electric vehicle batteries that reduces power consumption and extends sensor lifetime while still detecting gas leaks. The monitoring system has a gas sensor unit with multiple sensors that can be woken up selectively to measure gas levels. The sensors are in an idle state most of the time to save power. They are woken up based on events like temperature increases or accidents to check for leaks. This allows targeted sensor activation instead of continuous monitoring.

15. Battery Enclosure Monitoring System with Differential Gas Sensing for Thermal Runaway Detection

NEXCERIS INNOVATION HOLDINGS LLC, 2024

Monitoring system to detect and warn of potential thermal runaway in batteries before explosions or fires occur. The system uses sensors inside the battery enclosure to measure the amount of gas released during charging/discharging cycles. It also monitors the ambient atmosphere around the battery. By comparing the relative percentage changes in battery gas vs ambient gas, it can differentiate between normal battery emissions vs abnormal thermal runaway gases. This allows earlier warning of impending thermal runaway compared to just monitoring battery gas alone.

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16. Battery Monitoring System with Dual Gas Sensors for Differential Detection of Thermal Runaway Indicators

NEXCERIS INNOVATION HOLDINGS LLC, 2024

Monitoring system for batteries to detect early signs of thermal runaway, the condition that can lead to battery explosions. The system has a gas sensor inside the battery enclosure to detect gas released by the battery. It also has a separate gas sensor outside the enclosure to measure ambient gas levels. The system compares the percentage change in battery gas signal to the percentage change in ambient gas signal. If the battery gas signal percentage change exceeds the ambient gas signal percentage change, it indicates an abnormal increase in battery gas and could signal an impending thermal runaway. This allows early warning before explosive conditions occur.

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17. Method for Detecting Thermal Runaway Gases in Batteries Using Convolutional Neural Network-Based Sensor Data Analysis

GUANGZHOU MCM CERTIFICATION & TESTING CO LTD, 2024

Method for detecting thermal runaway gases in batteries using machine learning to improve accuracy and reliability of gas detection compared to existing methods. The method involves preprocessing and feature extraction of sensor data, training a convolutional neural network (CNN) model to predict gas concentrations, and setting up a dual alarm mechanism for out-of-control abnormality verification. The CNN model extracts spatial features from sensor data and performs regression to predict gas concentrations. Regular training with machine learning algorithms improves model accuracy. The dual alarm mechanism checks gas data against known standards to verify abnormalities.

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18. Sensor-Based System for Detecting and Mitigating Thermal Runaway Precursors in Electric Vehicle Batteries

GM Cruise Holdings LLC, 2024

Early detection and mitigation of thermal runaway in electric vehicle (EV) batteries to prevent fires and damage. The system uses sensors to detect outgassing, a precursor to thermal runaway, and alerts the fleet management system. This allows proactive response like evacuating the vehicle or redirecting assignments. On-board cooling and fire suppression can also be triggered. In EV facilities, the system identifies nearby vehicles and takes actions to protect them if a battery is outgassing.

19. System for Remote Trace Gas Detection in LiFePO4 Batteries via LoRa Wireless Communication

JIANGSU XUNHUI TECH CO LTD, JIANGSU XUNHUI TECHNOLOGY CO LTD, 2024

Remote monitoring of trace gases in lithium iron phosphate (LiFePO4) batteries using LoRa wireless communication to improve battery management safety. The method involves placing gas sensors inside LiFePO4 batteries to detect gases like hydrogen, hydrogen sulfide, and carbon dioxide. The sensor readings are wirelessly transmitted using LoRa to a remote monitoring device. The LoRa communication allows monitoring of large-scale battery installations without needing wired connections. The data is encrypted and checked for integrity to ensure secure and reliable transmission. The remote monitoring enables real-time detection and alerting of abnormal gas levels, which can indicate battery degradation or failure.

20. Gas Signal Detection System for Aqueous Zinc-Ion Battery Health Diagnosis

YANGTZE RIVER DELTA RES INSTITUTE UESTC HUZHOU, YANGTZE RIVER DELTA RESEARCH INSTITUTE UESTC, 2024

A system for diagnosing the health status of aqueous zinc-ion batteries based on gas signals. The system uses sensors to detect hydrogen (H2), oxygen (O2), and carbon dioxide (CO2) inside the battery. It analyzes the concentrations of these gases to diagnose issues like hydrogen evolution, corrosion, and passivation. Normalization processes are used to reduce cross-interference between gases. Threshold levels are set for accurate diagnosis of battery health.

21. Gas Monitoring System with External Control and Internal Ducted Sensor Network for Battery Compartments

22. Sensor Array System with Neural Network-Based Adaptive Gas Concentration Correction

23. Battery System Monitoring with Gas Sensors and Variable Correlation for Electrolyte Leakage Detection

24. Multi-Gas Sensor Array for Early Detection of Thermal Runaway in Lithium Battery Packs

25. Sensor-Based Battery Fault Detection Method Utilizing Multi-Parameter Monitoring for Thermal Runaway Stages

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