Why calling it 'impedance' ?

[Externet]

Greetings.
The cells forming a battery pack, and their internal characteristics, referred as 'impedance' instead of resistance. On day one I learned impedance is tightly tied to a frequency. Where is frequency present on direct current in order to use that term ? Seen used in several tutorials. Why ? Since when is that a proper way to refer to internal resistance ?

Pages 2-2 and 2-3 at
----> https://www.ti.com/download/trng/do... Cell Balancing - What to Balance and How.pdf

 

[FvM]

Battery internal resistance is in fact frequency and state-of-charge dependent. It's usually referred as impedance.

 

[barry]

impedance is the combination of resistance and reactance(frequency-dependent part). It is not incorrect to refer to a wholly resistive parameter as impedance.

 

[stenzer]

That might help to getter a better understanding

https://www.analog.com/media/en/reference-design-documentation/reference-designs/CN0510.pdf

 

[dick_freebird]

"Impedance" because something "impedes" the flow of current.
You could have said "resists" but that one's taken. So "resistance"
has its explicit dV/dI meaning, while "impedance" also includes
derivative and integral (inductor, capacitor) modes of "impeding".

 

[crutschow]

Resistance is fine if the load is pure DC, but you need to use impedance if the load has transient or AC current components.

 

[FenTrac]

Impedence is where you get to use the pythagorean theorem from math class. Impedence is eqial to the hypotenuse of a right triangle with one leg equal to resistance and the other leg the reactance, either capacitive reactance or inductive reactance to alternating current. If the reactance is 0 then the impdance equals the resistance.

 

[Externet]

Thanks.
And... this internal 'impedance-named' for direct current cells in batteries; is when charging, standing-by, or discharging ?

 

[FvM]

Impedance can be measured in all battery operation states. We built battery testers that are able to superimpose AC current during charge, discharge and idle state performing impedance spectroscopy.