# Heat source dependent on time AND temperature

Question asked by Thomas Annet on Oct 28, 2015
Latest reply on Nov 17, 2015 by Thomas Annet

Hello everybody,

I am trying to model a battery module and its heat transfer under Flow Simulation with a time dependent study. The aim is to know the final temperature of the battery under different environment.

I have a current (I) profile from the battery module as an input to determine the temperature increase of the module.

I am having problems with calculating the heat production (the heat source input in FlowSim) of the battery module since :

Using Joules formula :

Heat losses = Internal resistance of the battery*current^2        =>   Heat Losses = R*I²                         (neglecting other heat losses)

The problem is that the internal resistance R is dependent on the temperature, decreasing when the temperature increases, so I would need the direct measure of the temperature from the model to be accurate. I cannot calculate the heat losses on an excel sheet since I don't know what the temperature profile will be.

My question is :

Is it possible to implement in the heat source parameters, as a time dependent table, a power formula related to a temperature goal for each time step ?

Example: (Ri*(0.5*{PG Internal Temperature})*I^2

With   Ri = constant

I = depending on current profile

PG Internal Temperature = depending on temperature of the battery at each time step

I hope I was clear enough, don't hesitate to ask me anything if I was not.

Thank you in advance,

Thomas