Automotive Service Excellence (ASE) A6 Electrical/Electronic SystemsBattery Diagnosis and ServiceMedium
A technician is performing routine maintenance on a conventional flooded lead-acid battery. They notice a white, powdery substance accumulating around the positive battery terminal. What does this substance MOST likely indicate?
- ACorrosion due to electrolyte leakage or acid fumes.
- BA sign of an internal short circuit within the battery.
- CA healthy battery with normal chemical reactions.
- DSulfation due to undercharging or prolonged discharge.
Show answer & explanationAnswer & explanation
Correct answer: A. Corrosion due to electrolyte leakage or acid fumes.
White, powdery corrosion around battery terminals, especially the positive, is typically lead sulfate and other compounds forming due to electrolyte leakage, acid fumes escaping from the battery, or dissimilar metal reactions. This indicates a poor connection and potential battery health issues.
Why the other options are wrong
- B. An internal short circuit would manifest as low voltage and rapid discharge, not external corrosion.
- C. Corrosion is not a sign of a healthy battery; it indicates a problem.
- D. Sulfation occurs internally on the battery plates and is not typically visible as external white powder on terminals.
Battery Terminal Corrosion
Battery terminal corrosion, often a white or bluish-green powdery substance, is caused by acid fumes or electrolyte leakage reacting with the battery terminals and cables, indicating a poor connection.
- White/blue-green powder on terminals.
- Caused by acid fumes or leakage.
- Impairs current flow, leads to starting issues.
- Requires cleaning and terminal protection.
Memory trick: White Powder, Bad Power, Acid Fumes Sour.