You might be wondering what the hell a battery impedance test is right? Now, what a battery impedance test does it to measure the electrical path of the battery from the terminal plate to the next. Using this test, it becomes easy to identify a weak cell in a battery.
How to Conduct Battery Impedance Test?
To have this test done you need to apply the AC test signal to the test plates. You then need to measure the total voltage in the string and the total voltage drop by measuring individual cells and intercell connection. You need to do this in a sequence until the whole is measured.
Now for you to determine the impedance, you will need to apply the AC current signal and then have the measurement in the drop in voltage taken across the cell or alternatively the intercell connector. Once this is done, you can now use Ohm’s Law to calculate the impedance.
As much as measurement of the AC voltage is important, the measurement of AC current is equally important because you need to have in mind that other AC currents are present in the charging system and consideration needs to be taken on that.
Does Time Affect Battery Impedance?
Yes, time affects the battery impedance. As the battery gets old, the internal impedance increases. Regular impedance test therefore helps one to know the condition of the cells in a string and it becomes easier to know when to replace a battery cell and when to replace the whole battery. This becomes handy for planning purposes.
In the event that you know the weak cells, you will be able to do replacements in time and also prevent the entire string of cells from going offline and making the load no longer supported. This is very important because it helps to avoid major failures.
Relationship Between Battery Impedance and Battery Capacity
It has been proved that there is a strong correlation between battery impedance and battery capacity. It is therefore important to have the battery impedance measured before testing the battery capacity
For one to understand the capacity of the room, you need to first measure both the resistance and the reactance of the battery and this is achieved by doing the impedance test.
The impedance of the battery is not in any way affected by the frequency of the AC. The only two factors which affect the impedance of the battery are resistance and capacitance.
Why Should Battery Impedance Test Be Done
As mentioned earlier, this test helps you to identify weak cells. When weak cells are identified in time, one is able to take measures and have replacements done so that you avoid failure if the system.
This test provides a four-wire kelvin type measurement that provides reliable data set. This data set helps in making valid decisions in relation to the battery maintenance and replacement.
Conclusion
Apart from what is seen by the naked eyes, batteries a bit complex in the inside. There are several electrochemical reactions that take place inside the battery that cannot be seen by the naked eyes. Reactions such as ion diffusion and charge transfer cannot be seen but takes place from the inside.
The capacity of the battery decreases as the battery discharges because active materials are converted into inactive materials and also the acid in the electrolyte is depleted.
As these chemical reactions take place, the plates sulfate. As sulfation happens, the internal resistance to charge transfer also increases this is because the sulfates formed are less conductive compared to the active materials.