Back to Calculators

Battery Thermal Runaway Simulator

Interactive visualization of thermal propagation in a battery pack during thermal runaway

About this Simulator

This simulator visualizes thermal runaway propagation in a lithium-ion battery pack. When one cell enters thermal runaway (exceeds ~150°C), it generates extreme heat that can spread to adjacent cells, potentially causing a cascade failure. Watch how cooling rate and thermal barriers affect propagation speed.

Physics & Formulas

Heat Conduction (Fourier's Law):

$$\dot{Q} = k \cdot A \cdot \frac{\Delta T}{d}$$

Thermal Runaway Threshold:

$$T_{runaway} \approx 150°C - 200°C$$

Heat Generation Rate (during runaway):

$$\dot{Q}_{gen} = Q_{total} \cdot e^{-t/\tau}$$

How to Use

  1. Set Initial Cell Temperature - the starting temperature of all cells
  2. Adjust Ambient Temperature - affects cooling to environment
  3. Set Cooling Rate - simulates active cooling system effectiveness
  4. Adjust Cell Conductivity - how easily heat transfers between cells
  5. Toggle Show Temperatures to see cell temperature values
  6. Enable Show Heat Flow to visualize heat transfer directions
  7. Click 'Trigger Runaway' to start thermal runaway in a random cell
  8. Observe how heat propagates and potentially triggers adjacent cells

Frequently Asked Questions

What causes thermal runaway?

Thermal runaway occurs when a cell's internal temperature rises uncontrollably due to internal short circuits, overcharging, physical damage, or external heat. At ~130-150°C, the separator melts causing internal shorts, leading to rapid heat generation that can exceed 800°C.

How do battery packs prevent propagation?

Modern battery packs use thermal barriers between cells, active liquid cooling, fire-resistant materials, and cell venting systems. The goal is to isolate a failing cell and dissipate heat faster than it can spread to neighbors.

What do the colors represent?

Blue/Cyan: Normal operating temperature (20-40°C). Green: Elevated temperature (40-80°C). Yellow/Orange: Warning zone (80-130°C). Red: Critical/runaway (130-200°C). Dark red/black: Failed cell (post-runaway).

Inputs

25
25
0.5
2