Know How – Expert Edition – Proper Use of Digital Conductance Testers

MEASUREMENT

Electrical performances are usually found on the battery label, which provides information on its ability to both supply sufficient current to make the engine start and to process various electrical loads. The Cold Cranking Amps (CCA) of an engine determine the current needed for it to turn over, while the Ampere Hour Capacity (or Reserve Capacity) measures stored energy used for auxiliary vehicle equipment when the engine is not running and periods of battery inactivity.

LIMITATIONS

Digital conductance testers traditionally base results on either the impedance or internal resistance of a battery, relying on differing, internally programmed manufacturer algorithms to suggest potential CCA or available capacity. Estimates aside, there are several reasons why this can lead to inaccurate results. Firstly, most testers are made for use on fully charged batteries and, therefore, struggle to read the performance rating of partially charged batteries. Testers also have difficulty generating consistently accurate performance data when used in instant tests on batteries under no load or pressure. This is due to the fact they do not discharge the battery to observe current, voltage and time or measure its temperature. These are all important factors in accurately determining a battery’s performance and carrying out sufficient stress testing.

INCOMPATIBILITIES

Though newer models and designs have initial drop-down box options for new batteries which allows for better versatility, most digital conductance testers can be ill-suited to reading batteries due to their being designed for end-of-life use and various other incompatibilities. Manufacturers tend to build their batteries differently, leading to inconsistent charge, impedance, and internal resistance levels at the same voltage. This means that testers would have to be tailored to measuring specific brands and styles of batteries at differing temperatures and currents to get accurate readings. Due to having been developed for quick and easy use, testers also struggle to provide insight into the condition of a battery beyond being usable or having failed.

STANDARDS

Accurate readings of the CCA and capacity of a battery can only be developed by carrying out tests established by European Norm (EN), Japanese Industrial Standard (JIS) or Society of Automotive Engineers (SAE) specifications. This requires testing at precise temperatures and currents using specialised kits. When following these standards, one can determine whether the battery is fully charged and serviceable, discharged and in need of recharge/further tests, service abused or suffering from a manufacturer defect.