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 →Lemonergy Studio blocks
Electrothermal ECM cell worked example
Causal current-to-voltage model with charge and thermal states. Conserving ports are not yet included.
Blocks to use
- Electrothermal ECM cell
Accepts signed discharge current, ambient temperature and external heat. Charge balance drives SOC; an OCV table sets equilibrium voltage. The ECM adds two RC polarization states. Both variants include an ohmic loss and a lumped temperature state.
Inputs & settings
- Use the parameter values in the block reference.
- Bundled example verified on the production release of 28 October 2026.
This overview identifies the components to use. Follow the example in Lemonergy for their connections and settings.
- Review the block inputs, units and model limits.
- Open the Studio example and run its bundled model.
- Compare the output channels with the numerical checks; change one input and run again.
Example. Use the defaults below with Signed cell current (discharge positive) = 2 A, Ambient temperature = 298.15 K, External heat flow = 0 W. At 0 s, Terminal voltage is 3.68 V. Additional checks are listed below.
Observe. Inspect the outputs and numerical checks on the block reference page.
The external interface is causal current-to-voltage, without conserving terminals. Parameters are constant except the one-dimensional SOC-to-OCV table. No hysteresis, aging, reversible entropic heat or automatic parameter identification. The example verifies numerical behavior for synthetic parameters. Cell characterization and validation for an intended use are separate tasks.
Open Studio example →Lemonergy Studio blocks
Battery module worked example
Generated series/parallel cell hierarchy with individual SOC, RC and temperature states, KCL current sharing and optional thermal links. Causal pack-current boundary.
Blocks to use
- Battery module
Builds an explicit series/parallel hierarchy with a separate SOC, two RC voltages and temperature for every cell. Subtree voltage/resistance reduction and Kirchhoff current sharing determine each cell current. Optional thermal links exchange equal and opposite heat. Per-cell overrides introduce controlled variation.
Inputs & settings
- Use the parameter values in the block reference.
- Bundled example verified on the production release of 28 October 2026.
This overview identifies the components to use. Follow the example in Lemonergy for their connections and settings.
- Review the block inputs, units and model limits.
- Open the Studio example and run its bundled model.
- Compare the output channels with the numerical checks; change one input and run again.
Example. Use the defaults below with Signed pack current = 6 A, Cell ambient temperatures = [298.15, 298.15, 298.15, 298.15, 298.15, 298.15] K, External cell heat inputs = [0, 0, 0, 0, 0, 0] W. At 0 s, Pack terminal voltage is 10.92 V. Additional checks are listed below.
Observe. Inspect the outputs and numerical checks on the block reference page.
Bounded to 256 cells with the supported series/parallel construction. External pack current is imposed causally; no arbitrary geometry, conserving terminal adapter or topology reconfiguration. Each cell parameter set still needs characterization. The example verifies numerical behavior for synthetic parameters. Cell characterization and validation for an intended use are separate tasks.
Open Studio example →All connected Lemonergy block references
- Charge session thermal node
- Electrothermal ECM cell
- Battery module
- Module assembly
- Battery pack assembly
- Parallel cell group
- Tabulated OCV cell
- Thermal state-space model
- Edge-cooled plate
- Coolant pressure and temperature boundary
- Thermal mass
- Electrothermal resistor
- Insulated branch with initial temperature target
- Explicit unit conversion
- Parallel-channel plate
- Phase-change thermal mass
- Thermal conductor
- Controlled heat flow source
- Controlled temperature difference source
- Thermal convection
- Heat flow sensor
- Heat flow source
- Insulated thermal port
- Thermal radiation
- Thermal reference
- Thermal resistance
- Temperature sensor
- Temperature difference source
- Controlled thermal resistance
- U-channel plate
Studio interfaces connected to this concept
These components declare this quantity or operation. Their individual pages distinguish authoring metadata from numerical verification.
- Edge-cooled plate
- Insulated branch with initial temperature target
- Coolant pressure and temperature boundary
- Parallel-channel plate
- Phase-change thermal mass
- Thermal conductor
- Controlled heat flow source
- Controlled temperature difference source
- Thermal convection
- Heat flow sensor
- Heat flow source
- Insulated thermal port
- Thermal mass
- Thermal radiation
- Thermal reference
- Thermal resistance
- Temperature sensor
- Temperature difference source
- Controlled thermal resistance
- U-channel plate
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.