Deep Dive – Battery Repair Mode
This is a critical function of a modern battery charger and one that can deliver great value to the operator.
First, let’s define the problem that Battery Repair Mode is designed to solve. Here’s how battery sulfation is explained at https://electricalampere.com/:
Battery sulfation is a condition where lead sulfate crystals form and harden on the plates of a lead-acid battery. Here’s what happens:
• During discharge, a lead-acid battery naturally produces lead sulfate.
• When recharged, this lead sulfate normally dissolves back into the electrolyte (sulfuric acid).
• If the battery is left discharged for too long or is undercharged repeatedly, these sulfate crystals do not dissolve. Instead, they harden and stick to the plates permanently.
This leads to sulfation of the battery, making it less efficient and sometimes completely unusable.
What does this mean in the real world? When a battery is not accepting power in a normal fashion and therefore not increasing its capacity fully as a result of receiving a charge, in most cases, it is due to the presence of sulfation on the battery plates. As we noted in an article last month, “Sulfation is a natural process that takes place in a lead acid battery starting from the moment it is formed. Certain factors can speed that process (letting your car sit in the driveway unused for a 9-month stretch) and other factors can slow it, including servicing the battery regularly with a quality battery charger.”
Over time, sulfation will accumulate on every lead acid battery, gradually reducing the battery’s capacity. In the early stages, it is not noticeable, as the difference between 96% of total capacity and 92% is not significant in terms of application impact. During the downward sulfation march, normal charging will bring the battery’s capacity back up to a useful (but decreasing) charge, but, normal charging will neither arrest nor reverse the downward march. Eventually, every battery reaches a point of no return, when so much sulfation has accumulated that charging the battery no longer adds back any useful capacity. When a battery has reached this state, charging results in a very fast rise in voltage but no corresponding increase in power. The battery looks like it’s charged, but the minute you apply a load to it, it is totally dead.
