Battery Testers are used in the automobile industry to test the battery. These testers work by measuring the maximum CCA ( Cold Cranking Amps) the battery can provide.
Prior to the test, a selection is made in the battery tester pertaining to the type and make of the battery.
The battery tester typically applies a load which draws about 50% of the CCA rating of the battery. It measures the maximum current supplied and also the bounce back voltage after the test). It calculates the condition of the battery using this data by applying unique algorithms which are specific to the type of battery.
The battery tester also checks the condition of the battery by measuring the conductance. It does this by injecting a low voltage ac signal with a frequency between 50 - 100 Hz. This signal is used to measure the internal resistance of the battery. Battery tester manufacturers claim that the conductance of the battery will give an indication of the health of the battery.