Impedance/conductance measurements as an aid to determining replacement strategies

When to replace your battery is a critical and inevitable decision for the battery user. Replace too late and the reliability of the battery and the systems they serve to protect will be degraded resulting in the inevitable service failure. Replacement too early increases costs unnecessarily, and with typical VRLA battery life being between 4-8 years, depending on operational temperature, even a short time period can be a significant percentage of whole life costs. For the manufacturer, replacement decisions also present a dilemma: the replacement business would certainly be appreciated whilst on the other hand, repeat business may well depend upon customer satisfaction in achieving reasonable life and reliability in the first instance. This paper describes the importance of modern battery monitoring techniques and the interpretation of data that can assist the battery user in determining a coherent and cost-effective battery replacement strategy.