Insulation testers that are designed specifically to measure high resistance values are used in cell insulation resistance testing. The reference (resistance) values used to classify cells as defective or non-defective depend on the battery being tested. Be sure to check the reference values for the cells being tested and the. The test voltage is the voltage that the insulation tester applies to the cell under test. The appropriate test voltage varies from battery to battery. DC. Charging current is an important consideration from the standpoint of shortening test times. The charging current indicates the magnitude of the current output by the insulation tester. Due to their structure, battery. If you need to carry out highly reliable testing, it's important for the instrument you choose to provide a contact check function. This function checks the state of contact between the. An automatic discharge function serves to discharge the charge that accumulates in the battery. When the test voltage is applied, the battery's.