What is conductance?

Conductance is a unique electrical measurement that determines the ability of a battery to transmit current through its internal structure. As such, it gives a direct relationship to battery power. Internal conductive battery components include battery grids, active material and connectors that conduct electronic current as well as sulfuric acid electrolyte that conducts ionic current between and within the plates and plate separators.

Conductance is measured by probing the battery with a small AC current ripple that generates a small AC voltage response. Conductance is the relative ratio of the variation in current with the variation in voltage. It is a powerful tool for providing rapid and pertinent battery information without the need of discharging the battery with high currents that can be dangerous and leave the battery in a depleted condition.
In standby applications, various test data have shown that at low frequencies, the conductance of a battery is an indicator of battery state-of-health showing a linear correlation to a battery's timed-discharge capacity test result. This can be used as a reliable predictor of battery end-of-life.

Why test conductance?

Conductance testing is now a part of the IEEE standard for testing sealed valve regulated lead acid batteries. Extensive field test results have verified that conductance can be used to measure the capacity degradation of standby batteries. Many telecommunications providers and users of Uninterruptible Power Supply (UPS) systems use Midtronics standby testers to monitor their batteries in service. This acceptance of conductance methodology has resulted in a series of questions about conductance testing. The following are answers to some of the most frequently asked questions: