What kind of water must be used to replenish the battery fluid?

The proper choice for replenishing battery fluid is distilled water because it is free from impurities and minerals that could negatively affect the battery's performance and lifespan. Batteries, particularly lead-acid types used in forklifts, require a specific balance of chemicals, and introducing tap water or spring water can add undesired minerals and contaminants that can cause corrosion or reduce the efficiency of the electrolyte solution.

Distilled water is treated to remove dissolved solids and contaminants, ensuring that it does not contribute to any reactions that could impair the battery's functionality. This makes it essential for maintaining optimal performance and longevity of the battery, as impurities in other types of water can lead to reduced capacity, increased gassing (which can be hazardous), and overall decreased reliability of battery operation.

While deionized water might seem acceptable as it also removes impurities, it can still lead to aggressive corrosion in certain battery types due to the lack of necessary minerals. Therefore, distilled water is the recommended standard for maintaining battery fluid levels in forklift applications.