1. Introduction to IEEE 450 Annex J battery model

3. AC electrical theory (changing voltage, frequency is greater than 0) The property that limits electricity flow is called Impedance. When an AC voltage is applied there is resistance like DC but there are 2 new electrical elements. Capacitance Inductance

4. Impedance = Resistance + Capacitance Resistance + Inductance Resistance The term for Capacitance and Inductance Resistance is Reactance (X).

6. Impedance (Z)= Resistance (R) + Reactance (X) However because of the Reactance, Impedance is more complicated and can be best represented as vectors. X = X L - X C

7. Impedance can be represented in the following format.

8. A battery can be represented by a simplified lumped model so that Electrical Theory can be utilised to quantify the battery behaviour. Source IEEE 450-2010 Annex J

9. The Warburg Impedance Z w can be ignored because it’s effect is at extremely low frequencies outside the range of the existing technology in the market for online battery impedance measurements. = The battery inductance is very small and the battery capacitance is large. Therefore it is typical to only use one vertical axis, and the convention is for the axis to point upwards.

10. The battery impedance is dependent on frequency therefore if we take two measurements with different frequencies it can be represented as follows by points f 1 and f 2. The above result shows if two battery instruments with different test frequencies measure the same battery the readings are different.

11. Battery model Nyquist plot. Battery Nyquist plots are unique, like human finger prints, batteries have different plots and the differences are more significant for different types and sizes of batteries. In the battery/electrochemical industry a graph as per the previous slide is used when a battery’s impedance has been measured across a range of frequencies, this is known as a Nyquist plot.

12. Thank you.