I am trying to use a ageing equation from one of the models available in literature. I find that if I use the same constants provided by the authors, the total number of cycles is around 200 for 50% DOD. Which is an indication that the constants are directly out accelerated ageing model. Should I change the value in the equations if I would like to use it for regular application?
There are 5 main factors affecting battery aging. Temperature, Voltage (or SOC), DOD, C-rate and time.If the accelerated tests are well done, you should be able to relate those factors to aging and build a mode. Then, mormally, the aging constants (being from accelerated testing or not) should not change.
However, as you did not mention the aging model you picked up, it is hard to say.
As you put it, it seems that there is something missing or some confusion in the application of the model, but I cannot tell without further detail.
Good question!
Please keep in mind that empirical equations such as the aging equation that you mentioned have constants that are empirically derived. Hence, I recommend that you need to change the values of these constants to fit you accelerated test conditions.
Hope this helps answer your question.
Professor Yehia Khalil
Yale University
USA
True, the cells tested and the ones simulated should be exactly the same. Not all Li-ion batteries run equally, in fact, neither they do within the same chemistry (LFP, NMC, NCA...)!
Thank you for the answers professor Khalil and Dr Casals. My Question was whether the constants used in the empirical equations have to be changed while simulating non-accelerated real time applications (for the same type of cells).
Then again, it depends on the type of model you choose.
Some of them are based on Ah throughput, others count on %capacity loss per cycle or period of time under determined conditions, and so on.
Some of them should be addapted to real test conditions and the other's don't. You should verify if your model parameters and constants express aging according to all working conditions or just the empirical case. For example, the Arhenius-like curve that relates aging vs temperature has parameters that should not change, because it relates aging for a wide range of temperatures.
On the other side, If the equations that you have express aging only for the tested conditions, then it won't work.
For example, the aging parameters presented in this work under revision have parameters that do not change and respond equally to accelerated and non accelerated conditions:
http://www.preprints.org/manuscript/201610.0003/v1
Good luck!
Thank you for sharing your work Dr. Casals. The information is relevant to the experiments I am conducting now. I will explore further on it to check its suitability for my simulation.
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