Measuring conductance means knowing the state of health of a lead-acid battery.

Battery conductance is a fast, repeatable and effective electrical measurement that informs about the ease with which a battery can easily conduct current through its internal physical and electrochemical structure.

Battery conductance is measured by evaluating the voltage response of a specific frequency alternating current signal briefly applied to the battery (Admittance). The resulting conductance measurement provides relevant information about the battery without the need for complete discharge. When a battery ages or degrades, its conductance and capacity are reduced with a simultaneous and predictable drop in power due to the depletion of conductive active materials, their corrosion, sulphation or loss of electrolyte. Therefore, conductance is an indication of the battery’s health status.

The battery voltage indicates its state of charge but not its state of health. A battery (12V) in poor health and to be replaced can after charging to 100% of its physical and electrochemical capacity in its current state, indicate a voltage of 12.60V or more. But its available capacity reserve will be low and will no longer be able to supply the consumer circuit as it should, causing a failure of the powered system.

Conductance and loss of conductance are used to quickly assess the condition of lead acid starter and stationary batteries. As the battery ages, its internal components gradually wear out through corrosion, disintegration, electrolyte loss, electrolytic drying and other mechanisms. When this happens, the conductance cannot be restored and gradually decreases as the battery degrades, resulting in failure. Stationary batteries used as back-up power in the telecommunications industry and for inverter operation degrade predictably in terms of capacity and conductance over their lifetime. Conductivity thus makes it possible to quickly and safely determine the state of health of a functional battery, without having to carry out deep discharge tests.

Along with other battery information, conductance can also be used to detect cell defects, short circuits and open circuits that can cause early battery failure. Just as battery performance is significantly affected by temperature, conductance also varies with temperature in a predictable way due to the change in electrolyte conductivity. This is particularly true in cold weather (strong reduction). Conductivity factors are temperature sensitive and require information on the ambient temperature of the battery for correct compensation and a refined and accurate assessment.

The extreme efficiency of this technology lies in the establishment of a trend monitoring of battery conductance over time. Studies have shown that an individual battery produces a unique conductance « signature ». The use of a high-precision conductivity tester that follows the trend of this signature, from the installation and over its lifetime, is the most efficient battery management solution.

A maintenance program that conducts conductance tests of batteries and charging sources at regular intervals is the best maintenance practice that prevents the risk of total failure due to batteries.

When historical conductance results are not available for a given battery system, a generic reference value can be established and used.

This value is often found in the tester’s memory (if you have performed the initial installation), at the battery manufacturer’s or on our reference values page. Although it is important to note that the use of generic reference values is not as « accurate », it is still possible to identify batteries that have undergone severe degradation and significant changes in their condition by applying this method.

Franklin Electric encourages battery users to report individually on the condition of the batteries from the installation and then test regularly to monitor the trend of conductance degradation.

Conductivity technology allows testers, diagnostic chargers and monitoring systems to easily and quickly determine the health status and actual power capacity of a battery under a wide range of conditions. Years of laboratory and field testing have proven that the measurements provided by Franklin Electric testers provide a reliable indication of battery condition and health status compared to industry standards. Conductivity technology is recognized worldwide as the standard for determining battery health because the drop in conductance is directly correlated with the loss of capacity reserve. It is the test method required by many organizations around the world.

Leading users of UPS (Uninterruptible Emergency Power Supplies) systems around the world use the conductance testers provided by Franklin Electric for their battery management decisions.

Correlation between conductance and capacity reserve for Pb Acid batteries.
When the conductance is 60% of the initial value, then the capacity reserve drops very quickly (80%) and the battery must be replaced.

IXO ELECTRONIQUE – Official distributor of Franklin Electric testers in France –