Battery knowledge · Thermal management and heat transfer
Thermal model
A model of cell temperature: at its simplest one thermal mass with heat generation inside and convection outside, at its most detailed a 3D simulation of the pack. Temperature feeds back into every rate, so electrical and thermal models are usually solved together. [1]
- Also called
- lumped thermal model
Example
Heat approaches an equilibrium
Steady rise: 10 K. Time constant: 8.333 min.
C_th = 500 J/K, fixed ambient and heat input, uniform temperature.
Explore the graph
Thermal resistance sets the steady temperature rise; thermal mass sets the response time.
Steady rise: 10 K. Time constant: 8.333 min.
ΔT = P R_th [1 − exp(−t / (C_th R_th))]
Illustrative model. C_th = 500 J/K, fixed ambient and heat input, uniform temperature.
Use in Lemonergy
Design protocol or analysis tool
Inspect pack temperature
The separate Charge session can include a lumped thermal node.
Equation or tool to use
- Charge session thermal node
Balances heat and exchange
Inputs & settings
- Ambient temperature
- Thermal mass (J/K)
- Conductance (W/K)
- Heater availability
This overview identifies the components to use. Follow the example in Lemonergy for their connections and settings.
- Provide thermal mass and conductance.
- Compare two ambient temperatures.
Example. 100 kJ/K thermal mass and 100 W/K conductance give a 1000 s no-source temperature-difference time constant.
Observe. Temperature limits can pause charge; heater and mass are separate.
One node does not resolve gradients, coolant geometry or runaway. Studio’s native charger instead uses external temperature.
Open Design → Charge session →References & further reading
Technical references
- A General Energy Balance for Battery Systems
Dawn Bernardi, Ellen Pawlikowski, John Newman · Journal of The Electrochemical Society · 1985
Technical reference · Battery energy balance and irreversible and reversible heat contributions. Reduced thermal models require explicit assumptions and current-sign conventions.
Further reading on this topic
These sources provide broader context; they are not presented as citations for every statement in this entry.
- University Physics Volume 2, §1.6: Mechanisms of Heat Transfer
OpenStax, Rice University
Topic background · Conduction, convection, radiation and thermal resistance.