I know that the resistance from the battery is changing based on SOC. Is there appropriate ways to determine this quantity ? I see a lot of lead acid battery equivalent circuit, but cannot find appropriate ways to determine the capacitors and resistors estimations, which can help also.
A possible way to determine the capacitors and resistors (estimations), which might help you, is an expensive class, having "industrial specs", for power-EIS[1] systems. There are models (and modules) with optimized specs (in current and power) for the measurement of very LOW values (small modular regimes including low values, like Zreal
A possible way to determine the capacitors and resistors (estimations), which might help you, is an expensive class, having "industrial specs", for power-EIS[1] systems. There are models (and modules) with optimized specs (in current and power) for the measurement of very LOW values (small modular regimes including low values, like Zreal
Farhad I see from your question that your project is about battery charging calculations and computations, that might apply to (or be able to be applied to) a dynamic system (a varying SOC of a battery or series of batteries).
The battery equivalent circuit definition is a necessary one to derive some key values that can be used in other computations and in your case regarding charging, the key value of interest might be resistance, which fits in neatly with the a well known charging algorithm I = V/R.
But your question is about the "dynamic attribute" of a battery internal resistance (IR) relative to a dynamic battery state of charge (SOC).
We have already learned that IR varies with SOC, so what we are really most interested in (from a charging perspective anyway) is:
(1) how to derive the polynomial equation that might approximate this relationship in a new battery (or battery string); and
(2) what more do we need to know, and how to introduce another factor (battery age) into this polynomial.
Generally we are informed by the battery manufacturer about a battery I/V curve which is also easily tabulated through testing. This relationship mirrors the IR curve which can also be visualized as an IR/SOC curve.
A battery aging factor is easily established by test but this factor is not easily calculated by other means as it is battery type dependent.
Lawrence Coomber
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