Battery Temperature Variation in Fast Charging – MATLAB Analysis
How Temperature Gradients Behave Inside a Battery During Fast Charging – Full 3-D MATLAB Analysis (2025)
Fast charging is the biggest enabler for mass EV adoption — but it comes at a hidden cost: massive internal temperature gradients.
Even when the surface reads a safe 40 °C, the jellyroll core can hit 75–90 °C during 6C–8C charging. A gradient of just 5–6 °C across the cell is considered the safe limit for uniform aging and long warranty life. Anything higher accelerates SEI growth, lithium plating, and capacity fade.
In this post we use MATLAB R2025b + Simscape Battery + Partial Differential Equation Toolbox to show exactly where and why hotspots appear inside a real 50 Ah pouch cell during a 10-minute extreme fast charge.
The Battery Under Test
- Model: Valence U27-36XP (50 Ah NMC pouch cell)
- Dimensions: 306 × 172 × 225 mm
- Charge profile: 15 % → ~85 % SOC in 10 minutes (~6C average)
- Initial temperature: 27 °C
- Cooling: only bottom surface (realistic cold-plate scenario)
How We Built the High-Fidelity Thermal Model
- Electrical model → Pre-parameterized Battery (Table-Based) block from Simscape Battery
- 3-D Thermal model → Full geometry (jellyroll + tabs + casing) created in PDE Toolbox
- Reduced-Order Model (ROM) generated automatically and exported to Simscape (385 thermal nodes)
- Heat sources:
- Jellyroll → electrochemical losses from the table-based battery
- Tabs → I²R + weld resistance (0.75 mΩ)
- Casing → no internal generation
Key material properties used:
- Jellyroll in-plane thermal conductivity: 80 W/m·K
- Through-plane: only 2 W/m·K (highly anisotropic → heat trapped inside)
- Tab material: aluminum/copper → 386 W/m·K
- Bottom cooling area: 0.0526 m² with realistic thermal resistance boundary