Battery conductance is a rapid and repeatable electrical measurement that determines the ability of a battery to transmit current readily through its internal electro-chemical structure. It provides a direct relationship to battery power parameters.
Battery conductance is measured by evaluating the voltage response to a small, select frequency AC current signal briefly impressed on the battery. The resultant conductance measurement provides pertinent battery information without the need of bringing the battery to full discharge. As a battery discharges, its conductance and capacity are reduced with a simultaneous drop in power in a predictable manner due to the depletion of conductive active materials. Therefore, conductance is an indication of battery state-of-health as well as a function of the charge state of a battery.
Conductance and the loss of conductance have been utilized to quickly gauge the condition of lead acid starting and standby batteries in service. As a battery ages, its internal components gradually wear out through corrosion, disintegration, shedding, electrolyte dry out and other mechanisms. When this happens, conductance is unable to be restored and declines as the battery degrades, leading to failure. Standby batteries used as a power backup in the telecom industry and for UPS operations degrade predictably in capacity along with conductance during their service life. Without running extensive discharge tests, conductance can be used to rapidly and safely determine a functional battery’s state-of-health.
Together with other battery information, conductance can also be used to detect cell defects, shorts, and open circuits which can cause early battery failure. Just as battery performance is significantly affected by temperature, conductance also varies with temperature in a predictable manner due to the change in conductivity of the electrolyte. This is especially true at cold temperatures. Conductance factors are temperature sensitive and require temperature information for correct assessment.
The key to effective application of conductance technology is the appropriate trending of test results over time. Studies have demonstrated that an individual battery produces a unique conductance "signature" and the use of a high-precision conductance analyzer to trend changes in this signature, from installation through the life of the battery, is the most effective use of the technology. A program that involves conductance testing and battery maintenance on a regular interval to note changes in the battery and power plant condition is a good maintenance practice.
When historical conductance results are not available for a given battery system, a generic reference value can be established or employed.
This value can often be found in the test equipment memory, from the battery manufacturer, or on our Reference Values page. While it is important to note that the use of generic reference values is not as "accurate," it is still possible to identify grossly failed batteries and significant changes in battery condition by applying this method.
Midtronics encourages battery users to establish individual battery condition records from installation and trend accordingly using good record keeping.
Midtronics has developed an extensive base of patented and proprietary technology for battery management. Our conductance technology has been integrated into analyzers and monitors to quickly measure and analyze conductance and other battery data and to provide assessments through a convenient user interface. Analyzers use select probe frequencies to get the best conductance information for various battery types using proprietary electronic circuitry and filtering algorithms that can accurately measure conductance from extremely small variations in voltage and current while rejecting other circuit electrical noise. We have developed algorithms to measure a battery even under significant discharge and temperature conditions to determine its fitness for service. This greatly reduces the typical time necessary to fully recharge a battery before doing a high-rate load test, as is normally used by the industry.
Midtronics Conductance Technology allows testers, diagnostic chargers and monitoring systems to easily and rapidly determine a battery's true state-of-health and power capabilities under a wide range of conditions. Years of laboratory and field test data have proven that the measurements provided by Midtronics testers give a reliable indication of battery condition and state-of-health with respect to industry standards. Midtronics technology is recognized worldwide as the new standard for determining battery condition and controlling battery charging, and is the required test method for many organizations worldwide. Major backup power users throughout the world use Midtronics conductance testing as their guideline for battery management decisions.