Electrical Principles - Coursework Example

It involves taking snapshot of each cell at installation time and then measuring subtle changes as cells age. A 25% resistance increase over the initial reading provides hints to the battery’s overall performance drop. Measurement of a battery’s internal resistance is done through reading voltage drop on load current or AC impedance. The obtained results are considered ohmic values. There is a widespread held notion that internal resistance has a relation to capacity, yet this is not true.

Most batteries retain flat resistance throughout its service life. In figure 1 is the capacity fade and the internal resistance of battery cells. The circuit set-up contains the battery to be studied lying in series with a resistor. The potential difference across load is measured and so is the current for a different resistors/rheostat in the circuit. The idea is for the overall resistance of circuit changes so that the current is different each time. The reason that doing this is to tell us about internal resistance of battery because the potential difference across internal resistance is Vinternal resistance=I⋅r and it is possible to vary I by altering circuit resistance.

Where the potential difference across internal resistance is varying and hence, we add up all potential differences given as E=Vload +Vinternalresistance in determination of internal resistance. This can be represented