Deep Dive – The Ohms Knows

In this month’s Deep Dive, we are going to take a quick look at battery internal resistance and its usefulness as a predictive tool in estimating battery longevity and managing battery life cycles. First, what is internal resistance? All batteries, even when brand new, have a certain level of internal resistance, since their internal components are not perfect conductors of electricity. For instance, a battery’s electrodes and electrolyte are not 100% conductive. So, each battery starts out with a natural level of internal resistance. This internal resistance will increase as a battery ages, due to the natural chemical process that take place within all lead acid batteries.

Monitoring and tracking the internal resistance level of a battery can be very useful is assessing where that battery is in its life cycle. Granted, this usefulness only applies to vehicles and batteries that you will see over time. So, for service operations that might see a vehicle for service one time or only sporadically, this aspect of battery assessment is not helpful. Conversely, for captive fleets and other service operations, as well as vehicle owners, using battery internal resistance as a predictive tool can be very beneficial.

Many of our SOLAR BA Series digital tester models (BA427/BA327/BA227/BA9) provide an internal resistance measurement among the many pieces of feedback given when a battery test is performed with them, expressed in milliiohms (mΩ). For captive fleets and other service operations that service the same batteries installed in their equipment over and over again, this internal resistance data provided with each test can be very useful. As an example, if you had a fleet of service trucks that are equipped with the same Group 31 battery across the entire fleet, you could track battery internal resistance over time and develop a predictive pattern, such that when battery internal resistance reached XX.X mΩ, the battery was nearing end of life. This would be very useful, both in eliminating downtime resulting from dead batteries as well as budgeting for battery replacements in the next month, quarter or year.

So, as we say, The Ohms Knows, or, more accurately, the millohms knows. If you are performing fleet service, we recommend that you track battery internal resistance for your vehicles and add this tool to your predictive maintenance steps. Uptime means dollars saved and improved efficiency, as you know, and your battery testing solution can help you achieve greater uptime.

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