The ED-18 uses conductance technology to measure a battery's performance. In simple terms, conductance technology
sends a small amount of AC signal through the battery in order to measure the conductance of its internal components (plates). The conductance tester then takes this basic measurement and performs various algorithms (mathematical calculations) to determine the battery's performance. The following diagrams illustrate the basic aspects of conductance technology. The first two show the operation of a basic conductance tester. The last two illustrate the additional refinements of the ED-18 Analyzer that allow it to achieve a level of accuracy and functionality that surpasses previous conductance testers. The basic function of a conductance tester is to send a small electrical impulse signal through the battery to measure its internal conductance and resistance. Conductance testers use an algorithm to determine how the measured conductance compares to what the conductance of a performance battery should be according to its rated CCA. The algorithm also takes into account voltage and state of charge.

The algorithms incorporated into the ED-18 give an even more precise measurement, allowing for a marginal test classification and predicting the cold temperature at which the battery may fail to start the vehicle.

To enhance accuracy and functionality, the ED-18 incorporates refinements such as temperature measurement, battery age information and a local climate database based on the shop's zip code.