Understanding Thermal Runaway and How It’s Being Prevented in 2026

What is Thermal Runaway?

Thermal runaway occurs when a Cell’s temperature exceeds a safe threshold, often due to internal failure or external stress, triggering a chain reaction that leads to further heat generation. This feedback loop can cause battery packs to overheat, catch fire, or even explode. The primary causes of thermal runaway include:

• Mechanical stress (e.g., punctures or compression of cells)
• Electrochemical imbalances (e.g., overcharging, high discharge rates)
• Extended exposure to high ambient temperatures

Given the increased focus on electric mobility and renewable energy storage, industries are employing advanced technologies to minimize these risks.

Thermal Runaway vs. Thermal Propagation?

Before diving into prevention methods, it’s essential to differentiate between thermal runaway and thermal propagation.

• Thermal Runaway: This occurs at the cell level within a battery. It happens when a cell’s temperature rises uncontrollably, often due to internal failures like short circuits or overcharging, leading to further heat generation.
• Thermal Propagation: This refers to the spread of heat or fire from one cell to neighboring cells within a battery pack, eventually resulting in the failure of the entire pack (i.e., the catastrophic “boom”).

Preventing thermal runaway is crucial because if it escalates into thermal propagation, it can cause large-scale damage to the battery pack and potentially endanger passengers or surrounding infrastructure.

Mandated Safety Standards: AIS 156 Amendment

In response to the growing safety risks, regulatory bodies such as the Automotive Industry Standard (AIS) have implemented mandates since March’23 for thermal runaway detection, particularly in EVs. The AIS 156 Amendment specifically requires all EV manufacturers to integrate systems capable of detecting early signs of thermal runaway, ensuring that countermeasures can be taken to protect users.

The amendment is significant because it not only improves safety but also standardizes the technology used across the industry, making advanced battery management systems (BMS) with thermal runaway detection a necessity rather than an optional feature.

How Battery Manufacturers & OEMs are Preventing Thermal Runaway in 2026

Maxwell’s Proprietary Algorithm: Leading Battery Safety

At Maxwell, safety is at the core of our BMS design, and we’ve developed a proprietary algorithm to tackle thermal runaway prevention head-on. Built into our CT-Lite BMS, this algorithm offers advanced early detection capabilities by monitoring critical battery parameters and flagging warning signs before runaway conditions materialize.

Key Features of Maxwell’s Thermal Runaway Detection:

1. Internal Short Circuit Detection Our system monitors for voltage drops within cells, which could indicate an internal short circuit—a common precursor to thermal runaway. If a cell’s voltage drops below a configurable threshold and the drop persists over five seconds, the system triggers a runaway warning.
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2. Overcharging Detection Overcharged cells are a major cause of thermal runaway. The Maxwell BMS algorithm continually monitors for overvoltage conditions and sets off an alert if any cell exceeds the configured threshold.
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3. Abnormal Temperature Rise Detection By tracking the rate of temperature increase in each cell, our system flags abnormal temperature rises that could lead to runaway. If the rate exceeds a predefined limit, the BMS triggers protective measures.
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4. High-Temperature Detection Once any cell in the pack crosses a temperature threshold, the BMS sets off an error, stopping the situation from escalating into a runaway.

Built-in Safety Communications

Maxwell’s BMS also features advanced communication systems like CAN messages and GPIO outputs, which send real-time alerts to other vehicle systems. This ensures that any signs of thermal runaway can be addressed immediately, either by shutting down systems or triggering visual and audio alarms.

The Future of Thermal Runaway Prevention

As battery technology continues to evolve, the industry’s approach to thermal runaway is becoming more sophisticated. From enhanced cooling systems to AI-powered analytics and thermally stable materials, the industry is moving rapidly toward safer, more reliable battery systems.

At Maxwell, we’re staying ahead of the curve with our proprietary thermal runaway detection algorithm, ensuring that our BMS provides the highest level of safety and performance. As innovations continue, companies and consumers alike can look forward to a future where thermal runaway becomes a manageable, preventable risk.

By focusing on cutting-edge detection and prevention technologies, we’re not just preparing for the future of battery safety—we’re leading the way.

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