What is the function of a Pilot Cell in a battery bank?

The function of a Pilot Cell in a battery bank is to determine the condition of the entire battery bank's specific gravity. A Pilot Cell acts as a reference point among the cells in a battery system to monitor and assess the overall health and performance of the entire bank. By measuring specific gravity, the Pilot Cell provides valuable information about the electrolyte concentration within the batteries, which directly correlates to the state of charge and general condition of the battery bank. This measurement is crucial because it helps identify any potential issues within the cells, enabling timely maintenance or replacement to ensure optimal performance and longevity of the battery system.

In contrast, the other choices do not accurately describe the main role of a Pilot Cell. A Pilot Cell is not used simply as a backup or to serve as a secondary power source. While it provides useful data, it is not primarily designed for measuring voltage levels across the entire bank, nor does it enhance the capacity of the battery bank. Its specific role in assessing specific gravity is key to maintaining the health of the battery system.