Overview
An ambitious EV startup needed a thermal management system for their flagship vehicle's 100kWh battery pack. The system had to support fast charging while maintaining cell temperatures within safe limits to ensure longevity and safety.
The Challenge
Battery thermal management is critical for EV performance and safety:
- •100kWh pack with 7,000+ cylindrical cells in tight packaging
- •Fast charging generates extreme heat (up to 250kW charging)
- •Temperature uniformity critical for cell longevity and safety
- •Weight and cost constraints for competitive vehicle design
- •Wide ambient range from -20°C to 45°C operating conditions
"Fast charging is a key differentiator, but we can't compromise on battery life or safety. The thermal system had to be exceptional."
Our Approach
1. Multi-Physics Modeling
Developed comprehensive simulation framework:
- •Electrochemical heat generation models
- •Conjugate heat transfer coupling
- •Flow distribution analysis
- •Transient charging simulations
2. Cooling Architecture Evaluation
Compared multiple approaches:
| Architecture | Pros | Cons |
|---|---|---|
| Direct Liquid | Excellent heat transfer | Complexity, sealing |
| Cold Plate | Proven, reliable | Weight, uniformity |
| Immersion | Superior cooling | Fluid cost, weight |
3. Cold Plate Optimization
Selected and optimized indirect liquid cooling:
- •Channel geometry optimization
- •Manifold flow balancing
- •Adjoint-based shape optimization
- •Thermal interface material selection
4. Transient Analysis
Simulated real-world conditions:
- •Full fast charging cycles (20-80% in 22 minutes)
- •Repeated charge/discharge cycles
- •Extreme ambient conditions
- •Thermal runaway propagation scenarios
Simulation Details
Software: ANSYS Fluent, STAR-CCM+, COMSOL
Mesh: 45 million cells (full pack)
Physics: CHT + electrochemistry coupling
Validation: Module-level thermal testing
Thermal Performance
The optimized design achieved excellent results:
| Metric | Before | After | Improvement |
|---|---|---|---|
| Peak Cell Temp | 58°C | 46°C | -12°C |
| Cell-to-Cell ΔT | ±8°C | ±2°C | 75% better |
| Fast Charge Time | 30 min | 22 min | 25% faster |
| Pack Weight | Baseline | -8% | Optimized |
Safety Features
Incorporated thermal runaway mitigation:
- •Strategic thermal barriers between modules
- •Phase change material integration
- •Controlled venting pathways
- •Real-time monitoring points
Key Takeaways
- •Multi-physics simulation is essential for battery thermal design
- •Fast charging and longevity require excellent thermal uniformity
- •System-level optimization balances weight, cost, and performance
- •Safety considerations must be built in from the start
- •Transient analysis captures real-world thermal behavior
