I have obtained a dataset from CALCE which provided me with columns of data as follows;
Data_Point
Test_Time(s)
Date_Time
Step_Time(s)
Step_Index
Cycle_Index
Current(A)
Voltage(V)
Charge_Capacity(Ah)
Discharge_Capacity(Ah)
Charge_Energy(Wh)
Discharge_Energy(Wh)
dV/dt(V/s)
Internal_Resistance(Ohm)
Is_FC_Data
AC_Impedance(Ohm)
ACI_Phase_Angle(Deg)
How do I obtain the SoC from these data?
Attached picture shows some typical values.
What is the C-rate of your test? In theory, SoC is actually not defined within a single cycle, but with respect to the maximum capability of the battery.
A more accurate way to estimate SoC is to take the capacity of the instant you are interested at, and divide by the full capacity measured at a very slow rate (C/50, or even C/25 for some systems)
State of Charge (SOC) is the ratio of available capacity at any instant to the rated (maximum capacity) of the battery. So basically for your data,
SOC (t) = 1- (Discharge Capacity (t)/maximum Discharge Capacity).
This is my approach with very good results:
Conference Paper Battery Capacity and Discharge Current Relationship for Lead...
Thesis Discrete linear constrained multivariate optimization for po...
Once again I am surprised at the number of significant figures your variables are given, encouraging the observer to believe that factors like state of charge can be calculated to 6 significant figures. This is complete rubbish, no battery manufacturer would ever state the capacity of any one of their units to better then 1 or 2%. And no practical battery would keep this value for more than some weeks or months, and in a real array you would not know which cell had what charge that accurately. I grant that SoC can be calculated to say 2% for a new battery, but for older units some other more practical method must be employed - otherwise you would find in an otherwise working series of cells, a faulty cell being considerably overcharged and catching fire - or worse. I am not saying that SoC calculations have no value at all - but they have limitations in real world situations that must be kept in mind for safety's sake.
Dickson Neoh How can we calculate SOC variation with cycle number using this data? I want to use a RNN in which i want to predict SOC for next cycles.
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