Automotive Program Accreditation and Certification Practice Exam

When battery fluid levels are low, it is essential to use distilled water to bring the levels back to the appropriate mark. Distilled water is recommended because it is free from impurities and contaminants that could be present in tap water, which might negatively affect the battery's performance and lifespan.

Batteries, especially lead-acid types, contain a mixture of sulfuric acid and water. When the water levels decrease due to evaporation or other reasons, adding distilled water ensures that the chemical balance within the battery remains effective for proper function. This addition helps prevent sulfation and other battery degradation processes that can occur if the electrolyte levels are not properly maintained.

Using tap water could introduce minerals and contaminants that may lead to unwanted chemical reactions inside the battery. Similarly, adding baking soda or battery acid would disrupt the necessary balance of electrolyte components, potentially causing damage to the battery or leading to safety hazards. Therefore, distilled water is the most suitable and safe choice for correcting low battery fluid levels.