Which type of charge must always precede a test discharge?

The type of charge that must always precede a test discharge is the equalizing charge. An equalizing charge is essential because it ensures that all cells in a battery or storage system reach an optimal voltage level before discharging. This step is critical in maintaining the health and longevity of the battery system, as it equalizes the state of charge among the cells, preventing over-discharge of weaker cells during the testing process.

In the context of electrical systems, the equalizing charge helps balance the individual cell voltages, ensuring that they perform uniformly during testing. Without this process, weaker cells could become damaged or fail, leading to inaccurate test results or system failures. It is a standard practice to perform an equalizing charge to maintain the reliability and safety of the system during operation.