Battery performance capabilities continuously vary. Temperature, electrolyte and plate condition and SoC (state-of-charge) are among the primary influencing factors. Battery internal resistance (IR), polarization resistance (PR) and SoC, have been used as sources of information for providing real-time reporting of battery conditions and performance capabilities. Several techniques have been used to test the condition of storage batteries. These techniques include a voltage test to determine if the battery voltage is below a certain threshold, and a load test that involves discharging a battery using a known load. One technique involves measuring the conductance of the storage batteries. Battery testers typically determine the condition of batteries, i.e., the internal resistance of a battery, by either a load test or a small-signal analysis of the battery. Many batteries are rated by a measure of CCA (Cold Cranking Amps) according to an industry standard test procedure. Small-signal battery testers determine the condition of a battery by imposing a relatively low current AC signal across the terminals of the battery and analyzing the small AC voltage generated as a result of the internal resistance of the battery by comparing a value related to battery internal resistance or conductance or impedance or admittance to a threshold value that is a function of the rated CCA value of the battery. In CCA test battery voltage drop is monitored after discharging at a specified constant high current for 30 seconds.

Various battery analyzers have been developed to measure battery parameters. Specifically designated voltmeters and ammeters are the earliest known battery testers which remain in common usage. Hygrometers have also been used to measure the specific gravity of a battery and simple voltage measurements have been used to monitor the voltage of the battery. Although quite accurate when properly calibrated and operated, such devices are cumbersome to use, must be carefully maintained and stored, and can be rather expensive. More recently, battery testers have been incorporated into battery packaging containers. These testers, generally referred to as thermochromic testers, compromise an electrically conductive layer in thermal contact with a temperature sensitive color indicator layer. When the ends of the conductive layer are contacted with a battery’s terminals, electronic current flows through and create heat in the conductive layer. The heat so generated causes a change in the indicator layer if the voltage of the battery exceeds a predetermined threshold. The thermochromic tester includes a silver conductor that has a variable width so that the resistance of the conductor also varies along its width. As current travels through the silver conductor, the current generates heat that changes the color of a thermochromic ink display that is over the silver conductor. The thermochromic ink display is arranged as a gauge to indication relative capacity of the battery. The higher the current the more heat is generated and the more the gauge will change to indicate that the battery is good. Electrochromic testers differ from thermochromic testers in that the display layer changes color directly in response to the "open circuit voltage" of the battery. The accuracy of an electrochromic tester is determined by the rate of change of the open circuit voltage of the battery with depth of discharge and the sharpness of the change of intensity of the electrochromic display with voltage.

Conventional battery analyzers indicate the voltage of a battery subjected to a relatively small resistive load. The size or value of that resistive load might be varied depending on the type or size of the battery being tested. More complex testers may compare a battery's voltage under load to fixed voltages along a resistance ladder, where those voltage values correspond to specific levels of remaining charge. Generally, equally discharged batteries of identical voltage ratings, but different chemistries, will produce different results when compared to voltages along a fixed resistance ladder. Electronic battery testers have distinct advantages compared with conventional battery testers. In addition to their convenience as hand-held instruments without heavy cables, they are safer because the small currents drawn avoid dangerous sparks. Electronic battery testers do not require the battery to be fully charged in order to test nor will electronic battery testers weaken an already low battery. Electronic battery testers test the condition of a battery cell by drawing a small periodically switched test current from the battery. The resulting alternating voltage across the battery terminals is directly proportional to internal resistance. AC current load type electronic battery testers are high end battery testing equipment spectrum due to their sophistication and multifunctional capabilities. This type of electronic battery testers typically include a microcontroller with embedded software for managing the functions thereof, like keyboard sensing, display driving, and control of the analog circuitry which interface with the battery, for example. A user enters information of the battery under test using keys on a panel and reads the information through an alphanumeric display. The microcontroller controls the analog circuitry coupled to the battery under test and processes the measured battery signals to determine the battery's condition under control of the embedded software routines.