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What is OCV?

Anna Fedorova
Prodigy 20 points

Hi, everyone!

I am student and new to Battery Management System. I am interesting in Control Theory, so, that's why I choose BMS to make my graduation work. I found lectures of Dr.Gregory L.Plett to start.

Unfortunately, I really can not understand and found answer for my question on the Internet: what is the relation between two important parameters: State-of-Charge and Open-Circuit-Voltage. I only understand that SoC is the concentration estimation of lithium in the battery, and OCV is is the maximum voltage available from a battery, this occurs at zero current.

Dr.Gregory L.Plett give the MATLAB-code in his lectures, where he computed the fully rested open-circuit voltage for a particular state of charge and temperature point. What did he mean? Interpolation? If if is true, how this two parameters correlate with each other?

  • 0
    TI__Mastermind 25800 points
    Hello Anna,

    The best fit model for SoC is a subject of debate. At it's core, SoC is the remaining capacity over the full battery capacity. However, this model is based the battery parameters used in the algorithm used to calculate it.

    Here at TI, we use several different models to estimate the SoC of a battery and they are functions of OCV, temperature, impedance, chemistry and other parameters.

    Dr. Plett most likely has his own modeling algorithm for SoC and OCV, to which you were referring to. However, we do not have further information into his implementation. You may want to contact him for information regarding his SoC algorithm.

    The following link to Battery University's site is good at explaining a littler further into SoC measurement techniques.

    batteryuniversity.com/.../how_to_measure_state_of_charge

    This TI app note also describes a little more about the learning cycle performed on batteries using our Gauges.
    www.ti.com/.../slua597.pdf

    Hope this helps!
    Regards,
    Joel H
  • 0 in reply to Joel Hernandez II
    Prodigy 20 points
    Thanks a lot for your answer!
    I am going to inspect proposed links.