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DLR-VSDC / IEEE-MVC-2023

IEEE Motor Vehicles Challenge 2023
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battery aging cost question #29

Closed woojmn closed 1 year ago

woojmn commented 1 year ago 
    Hello,

I have a question about battery aging cost.

The battery aging cost is shown as follow picture at the cycle #4. J_batAging picture

In the picture, there is a section where the battery aging cost decreases while driving. Is it possible?

I think that it require to be integrated.

Originally posted by @woojmn in https://github.com/DLR-VSDC/IEEE-MVC-2023/discussions/26

JBRDLR commented 1 year ago

Dear @woojmn, the battery aging cost uses the average values e.g. cell current (for reason of model simplification) of the whole simulation run, so only the last value of the cost function is relevant and explains the behavior shown above. Best Jonathan

woojmn commented 1 year ago

Then, if the driving ends in 200 seconds, is the battery aging cost larger than if the driving ends in 1000 seconds?

As I understand, a larger battery aging cost reduces battery lifespan more. How can battery lifespan increase with more driving?

It is weird. The battery lifespan should decrease as the battery is used. In addition, the already reduced battery life cannot be recovered while driving.

JBRDLR commented 1 year ago

Please refer to the paper: image

@rpintodecastro probably you can give a better answer?

rpintodecastro commented 1 year ago

Dear @woojmn

This battery aging indicator takes into account the average current and temperatures of the battery over the cycle: batAging = f(I_avg, T_avg, ...) In the simulation results you shared, I think the average current is significantly higher during the initial 200s, which leads to an increase in this indicator.

Note also that the units of the battery aging indicator are in "mA/cycle". This means that this indicator capture the rate of variation of battery capacity (and not the absolute capacity loss over the simulation, as indicated in your comments).
Imagine that, at the end of the simulation (200s), you obtain a value of 100 mA/cycle with average current 0.7C and temperature 30deg. This means that, if you keep using the battery with the same average current and temperature until the end of the discharge cycle, your battery would lose 100mA of capacity.