 | Conductance | | Battery conductance is a rapid and repeatable electrical measurement that determines the ability of a battery to transmit current readily through its internal conductive structure. It thus provides a direct relationship to battery power parameters. Internal conductive battery components include grids, active material and connectors that conduct electronic current as well as electrolyte that conducts ionic current between and within the electrodes and separators. In particular, conductance can be correlated to the cranking current of starting batteries that must deliver large bursts of cranking power.
Battery conductance is measured by evaluating the AC voltage response to a small, select frequency AC current signal briefly impressed on the battery. The resultant conductance measurement provides rapid and pertinent battery information without the need of bringing the battery to full charge and then discharging the battery with high currents that can be dangerous and leave the battery in a depleted condition.
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. Thus conductance is a function of the charge state of a battery. Conductance and power lost through discharge can be restored through charging.
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 thus temperature sensitive and require temperature information for correct assessment.
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| | Conductance and the loss of conductance have been utilized particularly 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, its conductance is unrestorable and declines until it reaches a point at which the performance of the battery such as cranking becomes significantly degraded 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. Thus, without running extensive discharge tests, conductance and the loss of conductance, can be used to rapidly and safely determine a functional battery’s state of health and fitness for further service with respect to industry standards. Together with other battery information, conductance can also be used to detect cell defects, shorts, and open circuits which can cause early battery failure. |
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| Midtronics Conductance Technology | | Midtronics has embraced battery conductance and developed an extensive base of patented and proprietary technology for battery management. Midtronics Conductance Technology has been integrated into diagnostic testers to quickly measure and analyze conductance and other battery data and to provide assessments through a convenient user interface. Testers 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. Midtronics has 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 normally used by the industry.
Conductance is also incorporated into Midtronics Conductance Controlled Charging Technology. Because conductance changes with the charge state of the battery, by monitoring conductance during recharge it can be readily determined if and when a battery can be put back in service. C3 technology combines conductance monitoring technology with an advanced battery charging technique and an intelligent user interface to revolutionize the charging function. Diagnostic chargers based on C3 technology help eliminate nearly all bad/weak batteries in the first few minutes of charging, so only capable batteries are charged and problem batteries are replaced. Knowing the state of health of the battery throughout the process means maximum safety, efficiency and control. Using C3 Technology, the battery is charged safer, faster and simpler than ever before. Only good batteries are allowed to charge making charging more efficient and cost effective.
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| Midtronics has also integrated conductance technology into battery monitoring systems (BMS). These devices remain attached to the battery during its service life and continuously assess the health and power status of the battery. These devices combine conductance with measurements of current, voltage and temperature to give an unbroken record of a battery in service. With this battery history and continuous measurement, the battery capacity, discharge level and available power for starting can be constantly assessed for mission critical applications. BMS systems combine sophisticated algorithms to handle continuous streams of data coupled to hardware that is able to function in an often fluctuating and severe electronic environment.
In summary, Midtronics Conductance Technology allows our 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 battery warranty decisions at most automotive OEMs worldwide. Major backup power users throughout the world use Midtronics conductance testing as their guideline for battery management decisions. |
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