Learning Forum

[Vsing]

 I am trying to simulate a Lithium ion battery. the Min stop voltage that I have set is 0 V, and I am sure from the experimental results that the battery voltage remains above 2V atleast till 1200 seconds. Yet, the simulation stops due to this error.

Any suggestions about the solution controls, or any other idea?

Any help would be appreciated.

Thanks in advance.

[Vsing]

i opened the MSMD module files to check what the error meant, her's what I found. First I get the check flag -4, meaning convergence failure, shortly after that I get the check flag -14, meaning the IDA solver could not recover.

[Vsing]

No matter what scheme I choose from the solution methods, I always end up with convergence problems at the very same flow time instant. If anyone can suggest a possible solution please do so.

[Rob]

Looking at those residuals there is no flow. Should there be?

[Vsing]

There shouldn't be any flow.

[Rob]

What happens at 138s? Ie are there any changes in the model?

[Vsing]

No, there is no change in the model, atleast I don't make any. This happens at a battery discharge rate of,

5C at around 130s

3C at around 640s, there happens to be a sudden jump in the residuals uds1 and uds0, and the way the solution controls are, they aren't able to recover from that sort diverging tendency. My initial guess was that the battery must be running out of charge, I increased the capacity manifold, still the sudden jump in the residuals at nearly the same time step. I have tried smoothening the mesh as well.

[Vsing]

https://www.sharcnet.ca/Software/Ansys/16.2.3/en-us/help/flu_am/graphics/g_flu_tut_bat_newman_max_temp.png

none of the simulations at 5C or above have been carried out beyond a certain time value. Even in this paper referred in the Ansys bibliography, at high discharge rates, they haven't proceeded for longer times. L. Cai and R.E. White 

[DavFer]

Hi Vsing!nI'm having the same error on a simulation at 3C. Have you solved your problem?nI'm using an ECM model, and all the parameters are well settled. The problem is that, indeed, my discharge curve should stop at 1200 s, but the simulation is likely to take only around 600 s since then the voltage drop below 2 Vn

[spatel]

Hi, nThe IDA error means that the solver could not converge the electrochemistry sub-model. At SOC close to zero, solver convergence of the electrochemistry sub-model can be challenging as the gradients of voltage are steep and this requires the ECM parameters are carefully resolved at low SOCs. You can try to solve the Standalone EChem model to confirm that the IDA error is due to the sub-model solver divergence and not due to the potential equation solver convergence issues. Please see below image for some tips on IDA error associated with setup. Hope this helps.nn

[malthwier]

Hi Vsing!nI'm having the same error on a simulation and I'm using the same model p2d to simulate a Lithium ion battery. Have you solved your problem?n